IMAT Biology Lesson 6.1 | Anatomy and Physiology | Animal Tissues Part I

Summary

In this educational video, Andy from Med School EU explores the physiology of animals and humans, focusing on the four primary types of tissues: epithelial, connective, muscle, and nervous. He delves into the functions, locations, and specific roles of each tissue type, highlighting the importance of epithelial tissue in protection, absorption, and sensation, and connective tissue in support, binding, storage, and immune response.

Takeaways

• 📚 The video is an educational lecture on the physiology of animals and humans, focusing on the different types of tissues in the human body.
• 🔍 The classification of biological systems is reviewed, starting from cells to tissues, organs, organ systems, and finally the entire organism.
• 🧬 Four primary types of tissues are discussed: epithelial, connective, muscle, and nervous tissues, each with specific functions and locations in the body.
• 💪 Epithelial tissue's main function is physical protection, but it also plays roles in absorption, sensation, and secretion.
• 👤 Different types of epithelial tissues include simple squamous, simple cuboidal, simple columnar, stratified, and pseudostratified columnar, each with unique characteristics and locations.
• 🧠 Merkel cells in the skin are responsible for receiving sensations of touch and passing them on to the nerves.
• 🦴 Connective tissue has various functions including support, binding, storage, transport, protection, and immune response.
• 🦾 There are four major types of connective tissue: connective tissue proper, cartilage, bone, and blood, each with specific roles in the body.
• 🧬 Mesenchyme is an embryological connective tissue that develops into other types of connective tissue and is considered the beginning of all connective tissues.
• 🦴 Cartilage comes in three types: hyaline, elastic, and fibrocartilage, each with distinct properties and locations in the body.
• 🦴 Bone anatomy is detailed, including the epiphyseal plate, epiphyseal line, red bone marrow, periosteum, and the roles of fibroblasts and osteoclasts in bone repair and growth.

Q & A

What is the main topic of the video script?

The main topic of the video script is the physiology of animals and humans, specifically focusing on the different types of animal tissues.

How many primary types of tissues are discussed in the script?

The script discusses four primary types of tissues: epithelial, connective, muscle, and nervous tissue.

What is the fundamental function of epithelial tissue?

The fundamental function of epithelial tissue is physical protection, both internally and externally, from mechanical, chemical, and physical injury, as well as dehydration.

What are the different types of epithelial tissues mentioned in the script?

The different types of epithelial tissues mentioned are simple squamous, simple cuboidal, simple columnar, stratified, and pseudostratified columnar.

What is the primary function of simple squamous epithelium?

The primary function of simple squamous epithelium is to allow the movement of molecules across the cell, and it is typically found in the alveoli and the inner lining of blood vessels.

What is the main function of simple cuboidal epithelium?

The main function of simple cuboidal epithelium is to absorb fluids across both surfaces of the tissue, such as in the nephron of the kidney.

What is the primary function of simple columnar epithelium?

The primary function of simple columnar epithelium is absorption and secretion, which is prominent in the digestive system.

What are the four major types of connective tissue?

The four major types of connective tissue are connective tissue proper, cartilage, bone, and blood.

What is the role of fibroblasts in connective tissue?

Fibroblasts in connective tissue produce protein fibers and ground substance, including collagen, elastic fibers, and reticular fibers, which provide support and protection to cells.

What are the three types of cartilage mentioned in the script?

The three types of cartilage mentioned are hyaline cartilage, elastic cartilage, and fibrocartilage.

What is the primary function of the periosteum in bone anatomy?

The periosteum is the outer surface of the bone and plays a role in the growth and repair of the bone by providing a source of cells and nutrients.

What are the functions of red bone marrow?

The functions of red bone marrow include the production of red blood cells, platelets, and white blood cells, as it contains stem cells that differentiate into various blood cells.

What is the role of fibroblasts and osteoclasts in bone repair?

Fibroblasts and osteoclasts play a crucial role in bone repair. Fibroblasts lay down bone tissue, while osteoclasts break down bone tissue, maintaining a balance that is essential for the healing and remodeling of bones.

Outlines

00:00

📘 Introduction to Animal Tissues and Human Physiology

Andy introduces the topic of animal tissues and physiology, marking it as the final section of the biology curriculum. The video is divided into two parts due to the extensive nature of the subject. The focus is on the four primary types of tissues found in humans and animals: epithelial, connective, muscle, and nervous tissues. Andy emphasizes the importance of understanding these tissues for future medical professionals and provides an overview of the classification of biological systems, from cells to the entire organism.

05:00

🔬 Exploring Epithelial Tissue: Functions and Types

This paragraph delves into the specifics of epithelial tissue, highlighting its primary role in physical protection. It outlines the different types of epithelial tissues, including simple squamous, cuboidal, columnar, and stratified, each with unique functions and locations within the body. The paragraph also discusses the secondary functions of epithelial tissues, such as absorption, sensation, and secretion. Special attention is given to the skin, describing the structure of the epidermis and the roles of various cells within it, such as keratinocytes, Langerhans cells, Merkel cells, and melanocytes.

10:01

🦴 Connective Tissue: Diversity and Functions

The focus shifts to connective tissue, which comes in four main types: connective tissue proper, cartilage, bone, and blood. The paragraph introduces mesenchyme as the embryological connective tissue that develops into other types. The functions of connective tissue are explored, including support, binding, storage, transportation, protection, and immune response. The discussion then narrows down to connective tissue proper, which is divided into loose and dense types, with areolar tissue being a widespread example that encompasses various cells and fibers, including fibroblasts, collagen, and elastic fibers.

15:02

🛡️ Connective Tissue Defense and Cartilage Variations

This section continues the discussion on connective tissue, emphasizing its role in immune defense with cells like lymphocytes, macrophages, and mast cells. It then transitions into a detailed look at cartilage, describing its three types: hyaline, elastic, and fibrocartilage. Each type is distinguished by its composition and function, with hyaline cartilage being a precursor to the skeletal system, elastic cartilage providing flexibility, and fibrocartilage absorbing shock and resisting compression. The importance of understanding cartilage's limited blood supply and its implications for repair and nutrition is also highlighted.

20:04

🦴 Bone Anatomy and the Role of Cells in Bone Repair

The final paragraph of the script concludes with an exploration of bone anatomy, identifying key structures such as the epiphyseal plate, epiphyseal line, red and yellow bone marrow, and periosteum. It explains the growth process at the epiphyseal line and the function of red bone marrow in blood cell production. The paragraph also discusses the role of fibroblasts and osteoclasts in bone repair and growth, emphasizing the balance needed between bone formation and resorption. The importance of calcium regulation by these cells and its impact on overall bone health is also noted.

Keywords

💡Epithelial Tissue

Epithelial tissue is one of the four primary types of tissues in the human body and animals. It serves as a protective barrier against physical, chemical, and mechanical injuries, as well as dehydration. In the video, the speaker discusses the various types of epithelial tissues, such as simple squamous, simple cuboidal, simple columnar, stratified squamous, and pseudostratified columnar, each with specific functions and locations. For example, simple squamous epithelium is found in the alveoli of the lungs and the inner lining of blood vessels, allowing for the efficient exchange of gases.

💡Connective Tissue

Connective tissue is another primary tissue type that provides support, binding, storage, transport, protection, and immune functions in the body. The video script mentions four major types of connective tissue: connective tissue proper, cartilage, bone, and blood. Connective tissue proper is further divided into loose (e.g., areolar tissue) and dense (e.g., adipose tissue and reticular tissue). These tissues play a crucial role in maintaining the structural integrity and function of various organs and tissues.

💡Simple Squamous Epithelium

Simple squamous epithelium is a single layer of flat cells that facilitates the movement of molecules across the cell. It is delicate and specialized for this purpose. In the video, the speaker uses the alveoli of the lungs as an example, where this type of epithelium is crucial for the efficient exchange of oxygen and carbon dioxide. It is also found in the inner lining of blood vessels, allowing for the passage of nutrients and waste products.

💡Stratified Squamous Epithelium

Stratified squamous epithelium is composed of multiple layers of squamous cells, primarily serving a protective function. It is found on the skin, where it acts as a barrier against external injuries and pathogens. The video script highlights its role in skin protection, noting that it is not a simple tissue but rather a stratified one, indicating its complex structure and function.

💡Fibroblasts

Fibroblasts are cells found in connective tissue proper, particularly in areolar tissue. They are responsible for producing protein fibers and ground substance, which provide structural support and resilience. The video script explains that fibroblasts lay down a network of ground substance and produce collagen, elastic fibers, and reticular fibers, all of which are essential for the integrity and function of connective tissues.

💡Cartilage

Cartilage is a type of connective tissue that provides support and flexibility to various structures in the body. The video script discusses three types of cartilage: hyaline, elastic, and fibrocartilage. Hyaline cartilage, the most common type, is found in the nasal cartilage and the trachea. Elastic cartilage, with its higher concentration of elastin, is found in the ear and epiglottis. Fibrocartilage, known for its shock-absorbing properties, is found in the intervertebral discs and menisci of the knee.

💡Bone

Bone is a rigid connective tissue that provides structural support and protection to the body. The video script describes the anatomy of a long bone, highlighting the epiphyseal plate, which is responsible for bone growth, and the epiphyseal line, which marks the division between the epiphyses and the diaphysis. The script also discusses the presence of red bone marrow, which produces blood cells, and yellow bone marrow, which stores fat and aids in cell growth and repair.

💡Merkel Cells

Merkel cells are sensory receptors found in the basal layer of the epidermis, the outermost layer of the skin. They are responsible for receiving sensations of touch. In the video script, Merkel cells are mentioned as an example of the types of cells that exist in skin tissue, emphasizing their role in the sensory system.

💡Langerhans Cells

Langerhans cells are immune cells found in the epidermis of the skin. They play a crucial role in the immune response by detecting and responding to pathogens that penetrate the skin. The video script describes Langerhans cells as cells that maintain immunity and decide the immune response when a pathogen is detected.

💡Melanocytes

Melanocytes are pigment-producing cells in the skin that are responsible for the color of the skin. They produce melanin, which provides protection against UV radiation. In the video script, melanocytes are mentioned as the cells that determine the skin color and play a role in skin pigmentation.

💡Mesenchyme

Mesenchyme is the embryological connective tissue that serves as a precursor to various types of connective tissues, including cartilage, bone, and blood. It is essentially a stem cell that differentiates into different types of connective tissues during development. The video script explains that mesenchyme is the beginning of all connective tissues and plays a foundational role in their development.

Highlights

Introduction to the physiology of animals and humans, marking the last topic in the biology section.

Classification of biological systems from cells to tissues, organs, organ systems, and the entire organism.

Skin as an example of an organ composed of various tissues and its role in physical protection.

Four primary types of tissues in the human body: epithelial, connective, muscle, and nervous tissue.

Epithelial tissue's primary function of physical protection for both internal and external body surfaces.

Differentiation between simple squamous, cuboidal, columnar, and stratified epithelial tissues based on cell shape and layering.

Function of simple squamous epithelium in allowing molecule movement, exemplified by alveoli and blood vessels.

Role of simple cuboidal epithelium in fluid absorption, as seen in the nephron of the kidney.

Simple columnar epithelium's function in absorption and secretion, particularly in the digestive system.

Stratified squamous epithelium's importance in skin protection and its composition of dead and live keratinocytes.

The immune function of Langerhans cells in skin tissue and their response to pathogens.

Merkel cells' role in receiving touch sensations and relaying them to the nervous system.

Melanocytes as pigment cells responsible for skin color and their function in protection.

Overview of connective tissue types, including connective tissue proper, cartilage, bone, and blood.

Function of connective tissue in support, binding, storage, transport, protection, and immune response.

Description of areolar tissue as a widespread, least specialized form of connective tissue surrounding capillaries.

Importance of fibroblasts in producing collagen, elastic, and reticular fibers for structural support.

Role of immune cells like lymphocytes and macrophages in the defensive response within connective tissue.

Differentiation between hyaline, elastic, and fibrocartilage based on their structural composition and functions.

Unique properties of cartilage regarding its limited blood supply and its challenges in self-repair.

Bone anatomy lesson focusing on structures such as the epiphyseal plate, periosteum, and bone marrow.

Explanation of the balance between osteoblasts and osteoclasts in bone repair and calcium regulation.

Transcripts

[Music]

hi everybody this is andy welcome to med

school eu and today we've got a very

exciting day because it's it's another

wonderful day

teaching biology and

it's a special day because we finally

get to learn about the physiology of

animals and humans and it's also our

last topic in this dreadful biology

section

so today we are going to talk about

the animal tissues i'm going to break

down this first topic into two parts

because it is a lengthy topic and we're

going to cover it in two separate videos

and this is a really exciting uh last

topic as it does it discusses the

physiology of humans which is something

that we will be doing for our entire

career as

medical doctors all right so first let's

uh do our classification of systems this

is uh something very basic you should

have learned in middle school

however i think

a lot of times some of the very basic

concepts are the ones that we get wrong

on the exam

so

we must

know that there are there's a

classification of systems beginning with

cells

then going

over to tissues

then the organs organ systems and

then the entire organism for example

skin there is a

skin has various tissues it has various

cells

and skin is an organ

so there could be some tricky wording

some tricky questions but just uh go

through several examples of types of

questions with systems and you should

get the general grasp of what is

classified as a cell what is classified

as a tissue of cells

and so on so uh primarily today we are

going to discuss the types

of tissues i'm going to go over some

examples of those

so first of all

we have four different types of tissues

we've got epithelial tissue

connective tissue muscle tissue and

nervous tissue and

those are the fro the four primary types

of tissues

in the human body and animals as well

so we are going to discuss each one in

detail and we are going to go over

how each one works where they are

located and what's their main function

so first let's begin with epithelial

tissue and

an example of epithelial tissue is going

to be the the skin the most fundamental

function of epithelial tissue is going

to be physical

protection so in physical tissue it's

not going to be just skin protecting

from the outside but it is it protects

both these surfaces exposed internally

and externally

from

mechanical and chemical and physical

injury or even injury due to uh

dehydration so all of those things the

whole purpose of epithelial tissue is

for physical

protection so first we're going to label

a couple of layers of

of tissues so this uh this thin one

right here that is squished this is

most notably going to be skin or inner

linings of the kidney for example or

inner lining of

the stomach but here we're just going to

label types of epithelial tissues that

we have so this one is called simple

squamous and most notably the simple

squamous is located on the skin

now the next one is simple cuboidal so

these are all going to be just simple

this is going to be cuboidal

simple cuboidal and this one's going to

be simple columnar and this last one is

going to be stratified so it's not

simple it's

stratified and why it's squamous because

we always look at the top

few layers here to distinguish whether

it's squamous or cuboidal or

columnar as you can see here this is

stratified cuboidal because the top

layer is a cuboidal shape

and this last one is called

pseudostratified culinary before we go

into the details of what each one of

these does and their their main

functions where they're located we're

going to go over the rest of the

functions of epitheli of the epithelial

tissue so physical protection is

definitely the main function but it also

functions in absorption absorption and

sensations

and secretions so now let's discuss all

of these terms and where they're located

and their specific functions so simple

squamous

is just a single layer of squamous

epithelium

it is very delicate and it is

specialized to allow movement of

molecules across

the cell so this is a specialized

and it's single layered

and most prominently you would see this

in the alveoli

and why the alveoli well it has to be

very thin in order for molecules like

oxygen and carbon dioxide to pass

through

without any trouble

and that's going to be done through this

simple

squamous it's it's typically found in

the inner lining of blood vessels as

well

so that's called the endothelium

um it's found in the alveoli as i

mentioned and it's also found in the

abdominal cavity next one is the simple

cuboid and the primary function of

simple cuboid is going to be to absorb

fluids

and this happens across both ways of its

surface

and the most prominent example of this

would be the nephron in the kidney

because the nephron

is

our filtering organ of of the blood and

it absorbs lots of fluids when it

travels across the membrane now simple

columnar this elongated one would uh

most probably prominently exist in a

digestive system because its primary

function is going to be absorption

and secretion so to absorb and

stratified squamous is going to be

just layers of simple squamous and most

predominantly this would be

on the skin so its function would be

protection

and we are also going to discuss the

epidermis and just the skin

uh the tissue and the types of cells

that exist in uh in skin tissue

so first it's

important to label the top part here as

these are not live cells

they are dead cells and they're called

these are keratinocytes

so label these as

dead so these are

uh dead cells that are on the surfaces

of our skin that are there for

uh protection now of course just

underneath here the ones with the

nucleus are going to be live

keratinocytes

now this one right here this cell that

kind of protrudes everywhere this is

called the landerhond cell and their

and their main function is to

maintain immunity they would basically

decide the immune response that will be

used in case there's a pathogen that

comes through

the dead and the live keratinocytes

now this one right here also labeled at

the basal

layer this one's going to be called the

merkle cell

mercol

and the importance of merkle cells as

they

receive the sensations of touch so if

something was to touch the epidermis

something was to touch the skin the

merkle cells are the ones that are going

to receive that sensation and pass it on

to the nerves

and this last one here on the side is

going to be a milano site

milano

site

now again these labels are going to

change

based on the diagram that you look at

but the most important thing about is is

knowing the type of cells that exist

exactly where they exist so the merkle

cells exist on the basal layer which is

the layer just underneath the epidermis

you need to know keratinocytes exist on

the very top with the dead keratinocytes

protecting us

the landerhond cells are going to be the

cells that kind of mesh around and

they're going to be producing

the immune response in case there is an

attack by a pathogen and melanocytes are

the pigment cells so pigment

pigment cells so they're the cells that

are responsible

for the color of our skin next we are

going to discuss connective tissue

and there's four different types of

connective tissue there's connective

tissue proper which we're gonna label

and look at the diagram

there's cartilage

bone and blood

so cartilage and bone they're also

called supporting connective tissue

so these are the four major types of

of connective tissue in our bodies

mesenchyme so there's something called

mesenchyme

mesenchyme is basically a cell it's the

embryological connective tissue it's a

cell that eventually develops into all

uh these types of

cartilage bone blood connective tissue

proper

mesenchyme is the beginning of all that

it's the embryological stem cell

basically so the functions of connective

tissue

are to support

bind

so they bind to surfaces

store

so

storage

transport again

blood does transportation

protection it's also in protection bone

cartilage

all associated with protection

and

the more specialized would be the immune

protection function so first let's

discuss connective tissue

proper and connective tissue proper is

divided into two types there's loose

there's loose

and there's dense

all right so we are first going to

discuss the areolar tissue which is part

of the loose

connective tissue proper

so i know these terms are confusing for

now but just just stick with me i'm

going to explain what these are and the

purpose of them and then everything's

going to be

loud and clear

so this the image right here is

basically our areolar tissue

it's a

tissue that is sometimes thought of as a

prototype

for for that loose connective tissue

because it is a sample of all the

different types of cells and fibers

found in connective tissue so

connective tissue is made up of all

different kinds of cells and fibers and

it's kind of like a mesh of everything

here we're going to label a lot of these

structures and we're going to go over

a little bit about their significance

and why they're part of connective

tissue but there are three types of

connective tissue proper loose

there is areolar tissue adipose tissue

and reticular tissue

so areolar tissue which is the one that

we will be discussing here is a

widespread design of connective tissue

so why

i have chosen to discuss areolar because

it kind of encompasses everything that

is part of connective tissue

it's the least specialized

and it holds water and it's most often

surrounds capillaries so as you can see

here there's a blood vessel there

there's a blood vessel there so if you

could imagine if we do a cross-section

of part of our body so for example you

do cross-section of the arm and you

would have blood vessels running through

of course these are

blood cells

and all around there would be all kinds

of different cells all kinds of

different meshes around

that would be

supporting it and that's the connective

tissue that we are talking about because

it kind of connects

all the different types of systems

together it's kind of everything that

exists in between

all the cells and in between all the

different

organs and all the different organ

systems

so that filling of our bodies is

basically

connective tissue so first of all

the biggest part about all of this is

this area that's kind of shaded over

here

this area

that's underneath all of this

that area is called ground tissue and

another very important part of

connective tissue is called fibroblasts

fibro

the significance of fibroblasts

is that they are part of

areolar tissue that produce protein

fibers and ground substance so

fibroblasts are the ones that lay down

this network of ground substance and

they also produce protein

fiber so they produce

things like collagen so this all of

these large vessels here they're called

their collagen

and the function of collagen is that

they are strong flexible

and resistant fibers that protect cells

from

physical damage now they also produce

elastic fibers and elastic fibers would

be the ones that are these blue ones

these darker ones these are elastic

fibers

and they're also elastin proteins that

allows for stretch and recoil so if you

were to stretch your arm for example

these elastic fibers is what's going to

allow you to stretch the arm but it's

also going to recoil back once you put

the arm back in its original unstretched

face and finally it produces so

fibroblasts also produce reticular

fibers and reticular fibers are made up

of collagen proteins so same as this

large protein right here

but it's a different type than the the

white fibers it's tough but it is very

flexible and it forms a branching or

like this lattice

network that has been shown here and

it's found in organs like spleen and the

lymph nodes it has a special function

in its immune response that is way out

of the scope of this course so after

epithelial cells after

our epidermis has broken through so

if we have a pathogen a virus or a

bacteria that has you know there's a cut

and they break through the epithelium

the next line of defense is going to be

our connective tissue

and connective tissue has many ways

to produce a defensive response we got

lymphocytes macrophages so this one is

the

macro

phage

we also got our mast cells

that produce a response

we got a lymphocyte so this one right

here we'll label as lymphocyte

and we are going to talk about the

immune response in

in a way a greater detail than this

we're here we're just labeling the

different cells

and we could label this one as the

plasma cell

so these are these all play a the ones

in blue they all play a

major role in

immune response to a pathogen

next part of connective tissue is

cartilage so let's discuss cartilage a

little bit

and cartilage there's three types

there's hyaline cartilage elastic

cartilage and fibrocartilage

so hyaline cartilage is the most common

type of cartilage it is a high

concentration of fine

and thin collagen fibers

it is basically the precursor to the

skeletal system

as uh

it is

it is located in the epiphyses of the

long bones

so the very end of long bones and it

gives them that glassy surface so if you

have

you know seen a bone that's typically

like this

this glassy surface that's on

on the tip of each side

it's called the epiphyses

epiphysis epiphyses and that is where

hyaline cartilage is typically

located now some examples of hyaline

cartilage would be the nasal

cartilage

the trachea

a lot of trachea has hyaline cartilage

the connection of ribs

to sternum

they all contain hyaline cartilage in

order to facilitate

those connections

now looking at elastic cartilage it is

very similar to hyaline cartilage but

with a predominant number of elastic

fibers making this cartilage

very flexible and resilient to

pressure and force

it has an outer covering called the

perichondrium

so

the most important thing is to just know

it has higher level of elastin

it's just these fibers that allow

the cartilage to stretch

some examples of where you could find

elastic cartilage would be the uh the

ear is elastic cartilage as you can see

it's very mushy and squishy and it's uh

it's very movable

and also the epiglottis

and you will learn about epiglottis once

we talk a little bit about

the uh anatomy and finally

fibrocartilage is the chondrocytes and

the collagen fibers are arranged in

parallel

rows

so everything is arranged in parallel

this is very good at absorbing shock and

resisting

compression it is uh most commonly

founded found between discs the menisci

of the knee cartilage in between there

that's called the menisci that allows

for the two bones to move between each

other without

much friction and however

fibrocartilage is not covered with an

outer layer of

perichondrium meaning that

with compression

there could be damage to this layer so

uh if there is uh

movement against this layer of menisci

that's why you see a lot of meniscus

tears and they're not repairable the the

thing about cartilage to understand is

that there's not a lot of

blood or nutrients really going to

cartilage this tissue is not supply

supplied immediately

with nutrients like oxygen and

food that is able or to metabolize it

and be able to repair its cells

cartilage is not

repairable it's typically repaired

through surgery because you would have

to replace

the broken cartilage with a new

cartilage from another

part of the body so in the last part of

this video we are going to discuss bone

anatomy so in this long bone we're going

to label some of the most important

structures and as we discussed

the top part here that lines the

epiphyses so this is going to be

epiphyseal plate or i guess the

epithesis

feces

and

lining these epiphyseal ends is going to

be hyaline cartilage

now this line right here

that creates this division is where a

lot of the growth of the bone happens

and that line is called epiphyseal line

now this part that is closer to the

diaphysis side

this part right here is going to be the

red bone marrow red

and in this red bone marrow it's

extremely important to know

that

the function of it is to produce red

blood cells

platelets and white blood cells

because that is where the stem cells

are

formed and that is where the stem cells

are going to be used to create

a variety of other

blood cells

now the outer surface the outer part of

this bone is

called periosteum

and

and the name of this long bone

is going to be called compact bone

and inside the

diaphyses is going to be the yellow

bone marrow

and the yellow bone marrow we have

mesenchyme stem cells and they produce

cartilage they produce fat and they

produce bone so yellow bone marrow aids

in

the storage of fat

in cells called adipocytes and the main

function of this yellow bone marrow is

to provide the growth or the breakdown

of cells which we are going to discuss

next so when you break a bone

and

you are given a cast after realigning

the bones the bones have to

come together and

grow new bone cells so to speak

in order to

repair the damage so the repair of the

damage happens with a balance of these

fibroblasts and fibroclasts fibroblasts

and fibroclasts are cells

that break down bone if needed and

create bone if needed so fibroblasts so

the blasts they

lay down

lay down

bone

they make bone

and fibro class

they break down bone

break down

bone tissue and it's important to know

that we need both we need fibroclass and

we need fibroblasts

later we are going to learn about the

balance of calcium within the body and

it is

strictly regulated by these fibro class

and fibroblasts as to how much calcium

we're going to have in the blood

because the more bone you break down the

more calcium

you are going to have so this concludes

our lecture for today the first part of

animal tissues i hope this gives you

a brief introduction into the types of

tissues we have

and we have discussed in details the

epithelial tissue

and further on we're going to finish

connective tissue and

the rest including muscle and nervous

tissue

[Music]

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