Animal Tissues

Summary

This educational video script delves into the four primary types of animal tissues: epithelial, nervous, connective, and muscle tissues. It explains the specific functions and structures of each tissue, including the protective role of epithelial tissues, the signal-conducting function of nervous tissues, the supportive role of connective tissues, and the movement-enabling muscle tissues. The script also breaks down the different subtypes of each tissue, such as squamous, columnar, and cuboidal epithelia, sensory and motor neurons, and various connective tissues like areolar, fibrous, and cartilage. It provides a foundational understanding of the complex biological systems that support life.

Takeaways

• 🧬 Epithelial tissue is the body's protective layer, with cells often organized in a single or multi-layered structure, attached by a basement membrane.
• 🔍 Epithelial tissues can be identified by their geometric shapes, such as squamous, columnar, and cuboidal, each serving specific functions like protection, secretion, and absorption.
• 💡 Nervous tissue is responsible for conducting electrochemical signals and includes sensory neurons for sensing, motor neurons for movement, and interneurons for decision-making.
• 🧠 Nerve cells have four basic components: dendrites, cell body, axon, and axon terminals, with the position of the cell body determining the division between dendrites and axon.
• 🔗 Connective tissue supports, stabilizes, and protects the body's organs, and includes a variety of types such as areolar, fibrous, cartilage, blood, adipose, and bone tissue.
• 🩹 Areolar tissue is a basic form of connective tissue that binds epithelium and provides a loose connection between organs.
• 💪 Fibrous connective tissue is dense and strong, found in tendons and ligaments, providing flexibility without stretch.
• 🩸 Blood is the only liquid connective tissue, composed of lymphocytes, erythrocytes, and platelets, and is responsible for transporting nutrients, waste, and hormones.
• 🏋️‍♂️ Muscle tissue allows for movement and is categorized into skeletal, smooth, and cardiac muscle, each with distinct characteristics and functions.
• 🦴 Skeletal muscle is striated and under voluntary control, attached to bones for movement.
• 🌀 Smooth muscle is found in the digestive system and blood vessels, responsible for involuntary movements like peristalsis and blood flow regulation.
• ❤️ Cardiac muscle is unique, found only in the heart, and moves involuntarily without instructions from the brain.

Q & A

What is the primary function of epithelial tissue?

Epithelial tissue serves as a protective layer and lines the internal and external surfaces of the body, preventing unwanted substances from entering the body.

What is the role of the basement membrane in epithelial tissue?

The basement membrane acts as a sticky surface that helps attach epithelial cells to the underlying tissue, ensuring they stay close together for protection.

How do squamous epithelial cells differ from columnar and cuboidal epithelial cells in terms of shape and function?

Squamous epithelial cells are thin and irregularly shaped, often found in areas that require rapid healing like the mouth and skin. Columnar epithelial cells are elongated and often associated with secretion and absorption, found in the intestines and gallbladder. Cuboidal cells are square-like and also involved in absorption and secretion, located in sweat glands and the lining of the kidney tubes.

What are the four main types of tissues covered in the script?

The four main types of tissues are connective, epithelial, muscle, and nervous tissue, each with specific functions and structures.

What is the primary function of nervous tissue?

Nervous tissue is responsible for conducting electrochemical signals between the organs of the body and the brain, acting as the message pathways for the body.

How do sensory neurons differ from motor neurons and interneurons in structure and function?

Sensory neurons are responsible for sensing and receiving information from the environment, with the cell body often off to the side. Motor neurons control movement and have a centrally located cell body. Interneurons, or relay neurons, are found in the spinal cord and brain, relaying information between sensory and motor neurons.

What is the basic structure of connective tissue?

Connective tissue is composed of cells suspended in a fluid, matrix, or solid substance that provides support, stability, and protection to the body's organs.

What are the characteristics of areolar connective tissue?

Areolar connective tissue is loose and binds epithelium to other tissues. It is made mostly of collagen and elastic fibers, providing a flexible yet strong connection between tissues.

How does fibrous connective tissue differ from areolar tissue?

Fibrous connective tissue is more neatly arranged with a dense network of non-elastic collagen fibers, providing strength and flexibility without stretchiness, commonly found in tendons and ligaments.

What is the role of adipose tissue in the body?

Adipose tissue stores excess energy in the form of fat, provides insulation for heat retention, and cushions and protects organs due to its location around them.

What are the three types of muscle tissues and their primary functions?

Skeletal muscle is striated and responsible for voluntary movements, attached to bones. Smooth muscle is non-striated and controls involuntary movements in the digestive system and blood vessels. Cardiac muscle is also involuntary and striated, found only in the heart, responsible for its rhythmic contractions without brain instruction.

Outlines

00:00

🔬 Introduction to Animal Tissues

This paragraph introduces the topic of animal tissues, emphasizing the importance of understanding the specific functions and shapes of each tissue type. The main types of tissues discussed are connective, epithelial, muscle, and nervous tissues. The structure and function of epithelial tissue are highlighted, including its protective role and the presence of a basement membrane. The paragraph also mentions the stratified nature of epithelial cells and their geometric shapes, setting the stage for a deeper dive into the various types of epithelial tissues.

05:00

👨‍🏫 Exploring Epithelial Tissue Variants

This section delves into the three basic shapes of epithelial tissues: squamous, columnar, and cuboidal. Squamous epithelium is characterized by its thin, flat cells and is found in areas such as the mouth lining and skin surface. Columnar epithelium features elongated cells with oval nuclei and is associated with mucus secretion and food absorption in the digestive system. Cuboidal cells, resembling squares, are involved in absorption and secretion, commonly found in glands and the kidney. The paragraph also discusses the identification of these tissues through their cell shapes and nucleus characteristics.

10:01

💡 Nervous Tissue: The Body's Communication Network

The nervous tissue's role in conducting electrochemical signals is explored, detailing the structure and function of sensory, motor, and interneurons. Sensory neurons are responsible for receiving stimuli, motor neurons for muscle movement, and interneurons for relaying information between sensory and motor neurons. The paragraph explains the structural components of a nerve cell, including dendrites, cell body, axon, and axon terminals, and how these components contribute to the neuron's function in transmitting messages throughout the body.

15:03

🌱 Connective Tissues: Support and Stabilization

Connective tissues are introduced as a diverse group that provides support, stabilization, and protection for the body's organs. The paragraph outlines six major types of connective tissues, including areolar tissue that binds epithelium, fibrous tissue found in tendons and ligaments, cartilage that reduces friction, blood as the liquid connective tissue, adipose tissue for energy storage and insulation, and bone tissue providing the body's framework. Each type's unique structure and function are briefly described, emphasizing their role in connecting and supporting various body parts.

20:05

🏋️‍♂️ Muscle Tissue: The Engine of Movement

This paragraph focuses on muscle tissue, which is categorized into three types: skeletal, smooth, and cardiac muscle. Skeletal muscle is identified by its striations and multi-nucleated cells, responsible for voluntary movements. Smooth muscle, lacking striations, is involved in involuntary movements such as digestion and is found in the digestive system and blood vessels. Cardiac muscle, unique for its interconnected network of fibers, is responsible for the heart's involuntary beating. The paragraph highlights the distinct characteristics and functions of each muscle type, explaining their importance in the body's movement and regulation.

25:06

📚 Summary of Tissue Types and Functions

The final paragraph provides a comprehensive summary of the tissues covered in the script, reinforcing the key concepts and terminology. It reiterates the roles of epithelial, nerve, connective, and muscle tissues, and summarizes the functions of squamous, columnar, and cuboidal epithelia, sensory and motor neurons, and various connective tissues including areolar, fibrous, blood, bone, and adipose. The paragraph also distinguishes between the three types of muscle tissues, skeletal, smooth, and cardiac, and their respective roles in voluntary and involuntary movements. The summary serves as a recap of the essential information needed to understand the complexity and interdependence of the body's tissues.

Keywords

💡Epithelial Tissue

Epithelial tissue is a type of animal tissue that serves as a protective layer and lines the internal and external surfaces of the body. In the video, it is described as having a simple structure, often one layer thick or stratified, with a basement membrane that holds the cells close together. Examples from the script include the lining of the mouth, alveoli, and skin, where epithelial tissue plays a crucial role in protection and rapid healing.

💡Connective Tissue

Connective tissue is a diverse group of tissues that provide support, stability, and protection to the body's organs. The script explains that connective tissues are characterized by cells suspended in a fluid or matrix, which can be liquid, semi-liquid, or solid. Examples include areolar tissue, which binds epithelium to other tissues, and fibrous connective tissue found in tendons and ligaments.

💡Nervous Tissue

Nervous tissue is responsible for conducting electrochemical signals between the organs of the body and the brain, acting as the body's message pathways. The video script describes three types of nervous tissue cells: sensory neurons, motor neurons, and interneurons. Sensory neurons are responsible for sensing the environment, motor neurons for movement, and interneurons for relaying information within the spinal cord and brain.

💡Muscle Tissue

Muscle tissue is responsible for movement and is categorized into three types: skeletal, smooth, and cardiac muscle. The script explains that skeletal muscle is striated and involved in voluntary movements, such as running or lifting, and is attached to bones. Smooth muscle is responsible for involuntary movements like breathing and is found in the digestive system. Cardiac muscle, unique to the heart, is also involuntary and characterized by a network of branched fibers.

💡Squamous Epithelium

Squamous epithelium is a type of epithelial tissue characterized by thin, irregularly shaped cells with flattened nuclei. The script mentions that this tissue is found in areas where there is a need for rapid healing, such as the lining of the mouth and the surface of the skin, and it plays a crucial role in protection and self-renewal.

💡Columnar Epithelium

Columnar epithelium consists of elongated cells with an oval-shaped nucleus and is often associated with secreting mucus and digesting food. The script describes it as having a larger surface area due to cilia, which aids in absorption and protection. It is found in the intestines and the gall bladder, where absorption of nutrients occurs.

💡Cuboidal Epithelium

Cuboidal epithelium is characterized by cells that are square-like in shape with very spherical nuclei. The script explains that these cells are involved in the absorption and secretion of substances, such as hormones and sweat, and are typically found lining tubes, like those in sweat glands and the kidney.

💡Areolar Tissue

Areolar tissue is a basic type of connective tissue that binds epithelium and other tissues together. The script describes it as being composed of cells suspended in a matrix of collagen and elastic fibers, providing a loose connection between organs and attaching the epithelial tissue to underlying tissues, such as fat or muscle.

💡Fibrous Connective Tissue

Fibrous connective tissue is characterized by a dense network of non-elastic collagen fibers, providing strength and flexibility without stretchiness. The script mentions that this tissue is found in tendons and ligaments, where it is crucial for attaching muscles to bones and joining bones to each other.

💡Chondrocytes

Chondrocytes are the cells found in cartilage, a type of connective tissue that provides a smooth, glossy appearance and helps prevent friction. The script explains that these cells secrete a semi-fluid matrix in which they are suspended, contributing to the shock-absorbing properties of cartilage found in joints, ears, and noses.

💡Adipose Tissue

Adipose tissue is a type of connective tissue primarily composed of fat cells. The script describes its function as storing excess energy and providing insulation for heat retention or cooling, depending on environmental needs. Adipose tissue is found around organs for insulation and cushioning and under the skin to keep the body warm and supple.

💡Osteocytes

Osteocytes are the cells that make up bone tissue, a solid connective tissue that provides the framework for the body. The script explains that these cells secrete a solid matrix, contributing to the structure and function of bones, which is essential for muscle attachment and the skeletal system's overall integrity.

Highlights

Introduction to the four main types of animal tissues: connective, epithelial, muscle, and nervous tissue.

Emphasis on the link between tissue function and its shape.

Description of epithelial tissue as a simple, protective layer with few intercellular spaces.

Explanation of the basement membrane's role in holding epithelial cells together.

Identification of epithelial tissue by its geometric, square-like shape and nucleus shape variations.

Differentiation between squamous, columnar, and cuboidal epithelial tissues based on their shapes and functions.

Squamous epithelium's role in lining body surfaces and its quick healing properties.

Columnar epithelium's association with secretion of mucus and its presence in the intestines and gall bladder.

Cuboidal cells' function in absorption and secretion, found in sweat glands and kidney tubes.

Nervous tissue's function in conducting electrochemical signals and its three types of cells: sensory, motor, and interneurons.

Sensory neurons' role in sensing the environment and their unique cell body positioning.

Motor neurons' function in movement and their multi-polar structure for connecting to multiple locations.

Interneurons' function as decision-makers in the spinal cord and brain.

Connective tissues' role in supporting, stabilizing, and protecting body organs.

Areolar tissue's function in binding epithelium and its composition of collagen and elastic fibers.

Fibrous connective tissue's presence in tendons and ligaments and its non-elastic collagen structure.

Cartilage's function in preventing friction and its semi-fluid matrix with chondrocytes.

Blood as the only liquid connective tissue with its three major cell types: lymphocytes, erythrocytes, and platelets.

Adipose tissue's role in energy storage and insulation, and its composition of fat cells.

Bone tissue's structure with haversian systems and its function as the body's framework.

Muscle tissue categorization into skeletal, smooth, and cardiac muscle based on movement type and function.

Skeletal muscle's striations and multi-nucleated cells for voluntary movement.

Smooth muscle's non-striated spindle-shaped fibers for involuntary movements like breathing.

Cardiac muscle's unique branching structure, striations, and involuntary movement within the heart.

Summary of the key terminology and functions of each tissue type covered in the lesson.

Transcripts

hi everybody and welcome back today

we're going to be looking at the

different kinds of animal tissues

and going through this topic the most

important thing to keep in mind is that

every tissue has a specific function

and its function is linked to its shape

now there are four main types of tissues

that we are going to cover and that's

connective tissues

epithelial muscle and nervous tissue

now there are subdivisions of each of

these tissues we're going to go through

their specifics what they look like how

to identify

them i'm also going to look at some

micrograph pictures and some ways in

which

these can be asked in tests or exams

so to begin looking at our tissues we

need to start off with looking at

epithelial tissue one of the simplest

tissues in the body

and we need to look at its structure so

we can understand how

we use it and its function and why do we

find it in these specific locations

so our basic structure of our epithelial

tissue is very simple

the cells are often one layer thick as

we can see in this example

however they can also be multi-layered

in other words they can also be what we

call stratified

in other words you get like layers of

them on top of each other

and they're fairly simple cells but some

of the most important things we need to

remember

is that these cells are our protective

layer

and in order to hold them close together

we need something called a basement

membrane a basement membrane effectively

is a thin membrane that sort of acts as

like a sticky surface

for our cells to be attached to and

you'll notice that if you look very

carefully

there are very few intercellular spaces

in epithelial tissue

and that's because if we look at the

function you'll notice that

it is there for protection and lining

the internal and external surfaces of

the body and you don't want any openings

into the body if

that's the function you'll also notice

that there is a thin layer of connective

tissue sitting under the base

membrane and that's simply because we

need to connect

the epithelial tissue to the tissue that

is sitting underneath

this epithelial tissue which is

sometimes fat or muscle

another very defining feature of

epithelial tissues are their nuclei

now when we look at some of the examples

i'm going to tell you how to tell the

difference between

them in pictures but you want to keep an

eye out for the shape of the nucleus

some epithelial tissues they have a

circular nucleus like the one we can see

alongside

and then others have a more elongated

nucleus almost like a teardrop

shape so keep your eyes out for those

nucleus shapes and varieties the last

thing that we're going to familiarize

ourselves with

with basic basic epithelial tissues is

their overall

shape and epithelial tissues are mostly

geometric in shape

which means that if we look at these

cells these have a very square-like

shape to them

you will notice that a lot of epithelial

tissues follow a very similar pattern

they seem to have a

square or a rectangular shape to them

now let's look at the three most basic

shapes that we find epithelial tissue

in and that is a squamous collection

of cells a columnar and a cuboidal

now as you can already imagine and you

can see by the pictures

these tissues are largely based off of

their

shape and that's where they get their

name from and we're going to look at

their functions

and how best to identify them let's

start off with squamous epithelium

so what we're going to be looking for is

we want to look for a thin

irregularly shaped cell and if we have a

look at these you'll notice that

it seems as though they don't have a

very definite shape to them

sometimes they look like flattened

squares sometimes they look like a

flattened diamond shape

but essentially what you're looking for

is very flat tightly compacted cells

and you'll notice that a very defining

feature when you are looking out for

them

and how to identify them other than

their flattened appearance

is you are also looking for the

flattened nucleus

and the nucleus seems to be squashed in

this lower

area in the cell and so it's almost as

though you've taken

a circle and you sort of squashed it in

the middle so it's bulged out on either

side

where do we find the squamous epithelium

we find it in the lining of our mouth

alveoli and in the surface of our skin

and many other places

generally i like to remember squamous as

the

tissue that we often actually lose every

single day

think about all of the lining of your

mouth how it renews itself every day the

skin on the surface of your skin that

renews itself every day

so squamous tissue is something that you

are maybe very familiar with

and you'll notice that this tissue

actually heals very quickly and it needs

to

because remember epithelial tissues are

there to protect so you need to renew

that layer very quickly

now when it comes to columnar epithelium

we're looking for these

elongated cells essentially you're

looking for a very long thin rectangular

cell

and often the way we look for them and

how we identify them is we're going to

look for an oval

shaped nucleus if we have a look at the

photograph just above here

you'll notice that they're mostly

positioned pointing upwards

and they're not very circular the nuclei

so you're looking for that oval

shape now they can also be ciliated now

this columnar in this photograph is not

ciliated

but effectively what cilia look like are

these tiny hair-like structures

that grow off the surface of our

columnar epithelium and essentially all

you would call them is ciliated

columnar epithelium and basically what

they do

is all of these little cilia these

little hair-like structures they

increase the surface area of the

columnar epithelium

making a lot more surface area which

means that there's a lot more absorption

it's more efficient now generally

columnar

cells are associated with secreting

mucus

and so that's why it's important to have

a larger surface area because generally

mucus is also there for protection but

also for absorption and

the more surface area there is the

better you can do those jobs

another thing that columnar is

associated with as i mentioned is

digesting food

often this is the site of absorption

it's where

food is diet when it's digested in the

um digestive system in your

stomach and then when it moves into the

small intestines that needs to be

absorbed and it's the columnar's job to

do that

and so popular places that we find our

columnar epithelium is in your

intestines

and also in your gall bladder as well

last but not least is our cuboidal cells

and their name also gives it away they

look like

squares and so we're often looking for

these defined

square shapes um and they

also have a very very very spherical

nucleus and that is something that

really sets them apart from the other

epithelial tissues

is how circular their nuclei can be

um you'll notice that generally when we

look at cuboidal cells you'll see that

often you're given what looks like a

tube made out of them

and that's to signify generally the um

orientation the way in which they're all

they're way in which they're set inside

um

of our structures it's generally lining

tubes

and that then makes sense because if we

look at its function it's therefore

absorption and secretion

so a lot of these cuboidal cells main

job is

to absorb substances or to secrete them

and that secretion of substances can be

a variety of things it can be hormones

it can be sweat

it can be excess salts and potassium

there's a variety of things that these

cells can do

and we often find them in our sweat

glands in the thyroid gland and also

lining the tubes of the kidney

now if we move on to our next type of

tissue we're going to look at the

nervous

tissue and the nervous tissue is

responsible for

conducting electrochemical signals

between the organs of the body and the

brain

essentially these are our message

pathways it's where all the instructions

are

sent between the brain and the auger

organs of the body the effectors the

muscles

and essentially we have to get the

message from one location to the next

and we have three different kinds of

nervous cell tissues

that you'll be able to identify you must

be able to label these as well

um and it's really important to know

what they look like

because the slight differences between

them tell us

not just what message they carry but

also where and how do they connect to

other nerve cells so let's start off

with um actually i'm going to begin with

this sensory neuron over here

i'm going to start with the sensory

neuron because it is the neuron that

would be responsible for

sensing in other words the information

is coming in

to you from this cell and generally

things associated with sentry neurons

are your senses so

sight hearing smell etc and so what will

happen

is if we break down the overall

structure of a nerve cell

all nerve cells have four basic

components they have dendrites

they have a cell body they have an

axon and axon terminals and these are

the basics of what every single one of

these nerve cells

have now what's important to notice is

the difference in the structure so

our sensory neuron and how we tell what

it looks like is

its cell body which is this structure

over here

sits off to the side almost separate

it's got a little extension

and essentially what happens is this the

flow of the impulse always

enters through from the dendrites so

that means we're going to receive a

message

from your receptors maybe like your eyes

or your skin

you're going to sense the stimulus

that's going to move through the

dendrites

it's going to go past the cell body the

reason why it needs to go through it and

passed it is because the cell body will

determine where that message needs to go

next

and then it moves into the axon and then

finally out of the axon terminals

where does it go past there well i'll

get to that soon

what's really important is the naming of

these regions and so

this is the important part i want

everybody to know

the area before

your cell body is the dendrites

the whole area the area after

the cell body is known as the axon

and you're going to notice that this

label moves slightly

depending on which one we're looking at

let's look at the motor neuron

so a motor neuron is a neuron

responsible for movement

particularly with your muscles and

this is where you're going to carry out

your function so let's say for example

the sensory neuron has picked up that

you've put your hand

on a hot plate the stove is still on

now you need to move your hand away from

that hot stimulus

and so the only way to do that is for

the motor neurons to contract your

muscles and to move your hand away from

the hot object

so yet again you will notice that

this structure of the motor neuron is

slightly different you'll see that the

cell body is sitting right in the center

of our dendrites and you'll notice that

the axon label is a little sooner

and so this is what i want to clarify

with everybody because the cell body

sits inside of the dendrites

that means just this upper area

is our dendrite area whereas everything

beyond that

all this lower part here is the axon and

so

essentially wherever the cell body is

will determine where the axon is versus

where the dendrites are and so what

happens in our motor neuron

is yet again the message will come from

the dendrites

it will go down towards the axon

terminal

and then into the next neuron that's

next door

and motor neurons um are multi-polar it

means that they have lots of these

little

um dendrite branches as you can imagine

and that's because they need to be able

to send the message to multiple

locations

last but not least we have relay neurons

or we also call them interneurons um

and basically an interneuron is like the

name says like an in-between neuron

and these are the neurons that we find

mostly in the spinal cord and in the

brain

and interneurons literally relay

information between

the sensory neuron and the motor neurons

so if i were to draw in arrows

what happens is information will come in

from the sensory neuron

it will go to the relay neuron or the

interneuron a decision will be made

and then that decision will be sent out

of the interneuron

to our motor neurons to tell the motor

neurons what to do and how to

move yet again if we break down the

structure of the interneuron which is

very important

i want you to notice that the entire

area

before the cell body is the dendrite

the area after the cell body

is the axon and how do we tell that this

is an interneuron

well the cell body sits inside

of the center of our nerve cell and so

when you compare the three side by side

they have a lot of similarities but the

key difference

is where the cell body sits

moving on to connective tissues now

there are six major types of connective

tissues and essentially a connective

tissue is there to support and stabilize

and protect

your body's organs and to be a

connective tissue

you are have to have a certain structure

to be called a connective tissue

and that is you often need to be a group

of cells

surrounded by either a fluid or

a matrix and this

fluid or matrix can be a liquid but it

can also be a semi-liquid or a solid

and like the name gives away connective

tissues connect

one tissue to another some of them we're

very familiar with

and some of them are a little bit new to

us as well

so we're going to start off looking at

our

tissues um and we're going to cover

um the basics of what they all look like

how to identify them

and what are their functions now looking

at our first

type of connective tissue we are going

to look at

areolar tissue

and areolar tissue is a very basic

tissue

and what it does is it actually binds

epithelium it often sits below the

epithelial tissue

it's what we saw a little bit earlier on

in the video when we did a basic

structure of epithelium and we looked at

the cells in the basement membrane

you need to stick those epithelial cells

to the next tissue and the best way to

do that is to use areolar tissue

and in order for it to be a connective

tissue it must be cells

suspended in a matrix now this matrix is

mostly made out of collagen

and elastic fibers and we can see that

if we have a look at the diagram

the elastin fibers are the really thin

stretchy fibers

whereas the collagen fibers are much

thicker and they're not as

stretchy they give strength to this

particular connective tissue

and we often find areolar tissue in

between

our organs it actually attaches our

organs very loosely to each other so

they sort of stay in place

and it's also found like i said under

the surface of your skin

the next connective tissue is our

fibrous connective tissue

and this tissue is a little bit more

neatly arranged than its areolar chasm

and you'll notice that it's a dense

network of non-elastic collagen in other

words

we don't want this substance to be

stretchy we want it to be

strong and it needs to be flexible so it

needs to be able to

bend and twist but not stretch the

problem with stretching is that

sometimes it doesn't go back into its

original shape

now the easiest way to identify fibrous

tissue is you're going to look for these

elongated rows of fibers so if we look

up at the picture

you'll see what i mean by you're going

to look for these long

elongated fibers that are all going in

the same direction

and these little fibroblasts are the

cells

remember we're always looking for cells

that are suspended in

a matrix which in this instance the

fibroblasts are the cells

suspended in the collagen fibers now

where do we find these

well we mostly find fibrous tissue in

our tendons

and our ligaments remember that tendons

attach muscles to bones and in ligaments

you're going to join a bone to a bone

last but not least is cartilage now our

cartilage there are many different types

and i'm just going to do the very basic

idea of what cartilage is but cartilage

is

a connective tissue that provides a lot

of

prevention of friction and often yet

again it follows the same principle we

have cells suspended in a matrix in this

instance we have what we call

chondrocytes

and they are found in their sort of semi

semi-fluid

semi-solid matrix and often

cartilage has a very smooth glossy

appearance

if you have a look at the diagram you'll

see what i mean in that

each of these little purple individuals

is the cell

it's sitting in a little empty space

which we call the lacuna

or lucunai depending on how you want to

pronounce it it's this little empty

space

and these chondrocytes actually secrete

out

the fluid or the semi fluid that sits

around them that's this light blue

substance that's the actual matrix

and the purpose of cartilage is to

absorb

shock so we often find this in between

bones

and at our joints in our ear in our nose

it's important to know that there is

more than one type of cartilage

and depending on what the cartilage

needs to do

the next type of connected tissue is

blood and blood is actually the only

liquid connective tissue all the other

connective tissues are either a

semi-solid or completely solid

and when we look at blood there are

three major types of cells that we're

going to be looking at we're going to be

looking at the lymphocytes which are the

white blood cells

we're going to look at the erythrocytes

which are your red blood cells and then

you get something called platelets

platelets are technically cell

fragments they're not whole cells each

one of these cells has a different job

lymphocytes are for your immunity

and your red blood cells are for

carrying around gases

and platelets are there for blood

clotting

and so the most common functions of

blood is that we're going to transport

waste

nutrients and also hormones now blood

carries chemical messages around the

body

um often in a liquid form whereas if we

mentioned previously in the nervous

system the nervous system transports

electrical messages

and where do we find blood well we find

it in the circulatory system within all

the blood vessels the veins arteries and

capillaries remember it's important to

know that blood shouldn't be

outside of the arteries or the veins

and that might lead to internal bleeding

so you want to keep them inside the

circulatory system

next we have is the adipose tissue now

adipose tissue is largely made out of

fat cells interestingly enough you're

born with a certain amount of fat cells

and and if you gain fat the cells just

get bigger you don't actually grow

more fat cells and the purpose of

adipose tissue is to store

excess energy so this is when you don't

use all your carbohydrates up and you

need to store it for later

but it also provides insulation for heat

retention

but also to keep the body cool depending

on what needs to happen from the

external environment and where did we

find adipose tissue well we found it

around our organs it gives it a nice

insulation keeps your organs warm but

also cushioned

and it's also under your skin and it

allows your skin to insulate your heat

it allows your skin to be a bit more

supple and softer and flexible

last but not least is our bone tissue

and we'll go into bone in a more

detailed video later because it requires

a lot more explanation but the basic

idea is that bone is made up of a

network of systems

and what i mean by that is you'll notice

if you look at the diagram there seems

to be a circular structures

stacked next to each other they're

called have vision systems

and essentially what that means is these

cylindrical

or circular concentric circular

structures

give your bone their ultimate structure

and their function

and in yet again a connective tissue

style our osteocytes are these cells

that make up your bone and they secrete

the solid matrix that sits around them

so the osteocytes in this picture here

are represented by these little purple

cells

and those long sort of outgrowths are

how they secrete out your solid bone

matrix it provides a framework for your

body in other words it's

ultimately the structure of your body

because it makes your bones and it also

allows for muscle attachment

where do we find bone well we find it in

the skeletal system

finally we can look at muscle tissue and

muscle falls into three

categories we have skeletal muscle

smooth muscle and

cardiac muscle and um often the name

that

is given to them is representative of

actually what they do

and i'm going to tell you exactly how to

tell the difference between the three

starting off with skeletal muscle

so when we're looking at skeletal muscle

what we're looking for is

striations and it's one of the most

defining qualities

of skeletal muscle and striations are

these

things little stripes that run

down um the muscle fibers so you're

looking for those

striations it's one of the most

important qualities

and the reason why the striations are

there is those are the little components

that actually

contract and then relax which makes the

muscle actually move

another defining identifier for skeletal

muscle besides their stripiness

is that they have lots of nuclei so

they're multi-nucleated

and what that means is one muscle cell

will have

multiple nuclei embedded in it and you

can see that in the diagram above

all those dark little flattened circular

structures

are the multiple nuclei now skeletal

muscle is involved with voluntary

movement which means that's the movement

you choose to do that's like

running walking lifting up a glass

and those are things that are actively

happening within your brain and you you

think about doing them

where do we find the skeletal muscle

well it's attached to

our bones and it allows us to move

so when looking at smooth muscle we're

looking for muscle that is

not striated and that is really its

defining characteristic there are no

stripes and you need to look very

carefully because when you look at the

picture above

it sort of looks like those are stripes

but don't be fooled those are the muscle

fibers but if you look at the individual

fibers

you will notice that there are no stripy

appearances and what you're actually

looking at

are these thin spindle shaped fibers now

spindle

literally means if we look at the cell

shape you'll notice that it is quite

swollen in the middle and then it gets

skinnier at the end that is what spindle

means

it means it's quite big in the middle

and then it tapers off and it gets

thinner and thinner

near the edges of the cell now in terms

of its function

smooth muscle is responsible for

involuntary movement these are movements

you don't have to think about they just

happen like

blinking or coughing or breathing and so

often we find these

um muscle tissue types in the digestive

system

and in our blood vessels these are

systems that we don't have to think

about moving they just move

for us finally we're going to look at

the cardiac muscle

now the cardiac muscle is a tricky one

because we often confuse this with

skeletal muscle when we look at some of

the diagrams

and what you're going to look for is its

most defining feature which is it's that

it's a network of branch muscle fibers

and if you look at the diagram above

you'll notice what they mean

you have a muscle fiber and another

muscle

fiber and they are connected with these

branch branch-like structures that

run through them they're almost

interconnected

so you're looking for those branches to

tell you

if this is cardiac muscle or not

something else that can help you look

for

and identify cardiac muscle is it does

have striations

so that might help you tell that it's

not smooth muscle because it has

striations

but if you're going to tell the

difference between skeletal and

cardiac muscle the striations are a

little bit

fainter they're a little bit fuzzier in

this diagram

in the micrograph they're very difficult

to see so what we are looking for here

is this branchiness this almost fibrous

look to it

and that's what we're looking for that's

what's the most defining feature

in terms of its movement it's

responsible yet again for involuntary

movement

but very very specific involuntary

movement because it's only found in the

heart that's the only place it's found

hence the name

cardiac interestingly enough the heart

is

made up of a muscle the cardiac muscle

which is the only muscle in the body

that can move on its own in other words

it requires

no instructions from the brain in order

to function

in this video we have covered an

enormous amount of content with a lot of

terminology and these are the most basic

terminology words that you need to have

known from this topic

first of all we need to know that we

have four types of tissues we have the

epithelial tissue which

lines the internal instrumental surfaces

provides

protection the nerve tissues which

transport

electrochemical signals the connective

tissue which holds all the tissues

together

and our muscle tissue which allows

movement we looked at

squamous epithelium which is the

squashed squares we have the columnar

the elongated longer cells they secrete

things

and the cuboidal cells are square like

cells that line the tubes they also

secrete some substances

we looked at the sensory neuron which is

how you sense your surroundings

how you see hear touch taste motor

neurons which is how you move

it's the neurons responsible for telling

your muscles to move

and interneurons these are the neurons

that make all the decisions within the

spinal cord and the brain

we then looked at the connective tissues

areolar is loose it sits just under the

surface of the skin

and basically attaches epithelium to

other tissues

fibrous which is what we see in our

tendons and ligaments it's not very

stretchy

we've got blood the only liquid

connective tissue

bone our solid connective tissue which

provides the framework for our body

adipose which is where we have our fat

cells for insulation and also

for cushioning and then we looked at

muscle we have skeletal muscle which is

striated it can move on its

um when given instructions which means

it's voluntary and it's attached to our

bones

smooth muscle is involuntary it moves

without us telling it

it's responsible things like breathing

for digestion we find it in the

digestive system

we find it in your esophagus

and lastly we looked at your cardiac

muscle this is the muscle that the heart

is made out of it's also involuntary

muscle it moves

on its own and it's very special because

it's the only muscle in the body that

can move without being told to move by

the brain

i hope you've enjoyed this lesson and

that has been very useful to you and i

will see you all again soon

bye