Muscle Tissue | Skeletal, Cardiac, and Smooth
Summary
TLDRIn this educational video, Dr. Mike explains the three muscle types in the human body: skeletal, cardiac, and smooth. He compares their functions, structures, and how they contract. Skeletal muscles enable voluntary movement, cardiac muscles control the heartbeat involuntarily, and smooth muscles move substances through organs like the digestive system. He delves into their microscopic structures, explaining the differences in their nuclei, appearance, and striations. Dr. Mike also highlights how cardiac and smooth muscles work without conscious control, contrasting them with the voluntary actions of skeletal muscles.
Takeaways
- 💪 Muscle tissue is one of the four body tissues and is responsible for mechanical work, allowing movement, blood flow, and substance transport.
- ⚡ Muscles are excitable tissues, meaning they can be stimulated to perform an action like contraction.
- 🧠 Skeletal muscle is voluntary, meaning we consciously control it, while cardiac and smooth muscles are involuntary and work automatically.
- 🧬 Skeletal muscle cells are cylindrical and multinucleated, while cardiac muscle cells are branched and uni/binucleated, and smooth muscle cells are spindle-shaped and uninucleated.
- 🏋️ Skeletal muscle has the greatest capacity for growth (hypertrophy) because of its multiple nuclei, which allows for efficient protein synthesis.
- 🔍 Skeletal and cardiac muscles are striated, showing stripe-like patterns due to the arrangement of actin and myosin filaments. Smooth muscle lacks these striations.
- 🔗 Cardiac muscle cells are connected by intercalated discs and gap junctions, allowing for coordinated contractions across the heart muscle.
- 🩸 Smooth muscle contracts in multiple directions to help move substances through hollow organs, such as the digestive tract and blood vessels.
- 🧩 Sarcomeres are the smallest contractile units in skeletal and cardiac muscle, where myosin heads bind to actin to facilitate contraction.
- 🫀 Cardiac muscle contracts as a unit, with electrical signals spreading through gap junctions, enabling the heart to beat in a coordinated manner.
Q & A
What are the three different types of muscle tissue in the body?
-The three types of muscle tissue are skeletal muscle, cardiac muscle, and smooth muscle.
What is the primary function of muscle tissue?
-The primary function of muscle tissue is to perform mechanical work, which allows for movement of the body, blood flow, and movement of substances through organs like the digestive and reproductive systems.
What does it mean for muscle tissue to be 'excitable'?
-Excitable tissue can respond to stimuli. For muscle tissue, this means it can be excited to contract when stimulated, helping to move the body, pump blood, or push substances through organs.
What distinguishes skeletal muscle from cardiac and smooth muscle in terms of control?
-Skeletal muscle is under voluntary control, meaning we consciously move it, while cardiac and smooth muscle are involuntary, functioning without conscious effort.
How do the shapes of skeletal, cardiac, and smooth muscle cells differ?
-Skeletal muscle cells are cylindrical, cardiac muscle cells are branched, and smooth muscle cells are spindle-shaped.
Why does skeletal muscle have multiple nuclei, while cardiac and smooth muscle cells have fewer?
-Skeletal muscle is multinucleated to support greater capacity for growth and protein synthesis, which is important for hypertrophy (muscle growth). Cardiac muscle has one or two nuclei, and smooth muscle has only one nucleus due to their lower capacity for growth.
What are striations, and which muscle types have them?
-Striations are stripe-like patterns seen under a microscope, created by the arrangement of actin and myosin filaments. Both skeletal and cardiac muscles have striations, while smooth muscle does not.
What is the role of actin and myosin in muscle contraction?
-Actin and myosin are proteins that interact during muscle contraction. Myosin binds to actin and pulls on it, shortening the muscle fibers and creating contraction.
How does the arrangement of actin and myosin differ between smooth muscle and the other two muscle types?
-In skeletal and cardiac muscle, actin and myosin are arranged in parallel, allowing for uniform contraction. In smooth muscle, they are arranged in a more random, criss-cross pattern, allowing the muscle to contract in multiple directions.
How do cardiac muscle cells communicate with each other during contraction?
-Cardiac muscle cells are connected by intercalated discs, which contain gap junctions that allow electrical signals to pass from cell to cell. This enables the entire heart to contract in unison during a heartbeat.
Outlines
💪 Introduction to Muscle Types and Functions
Dr. Mike introduces the three types of muscle tissue—skeletal, cardiac, and smooth—and their functions. He explains that muscle tissue is excitable and plays a key role in movement, whether it's conscious movement of the body, involuntary movement in the heart, or movement of substances in internal organs like the digestive system. Muscles contract when excited, and different muscle types are responsible for various movements in the body.
🦴 Skeletal Muscle: Structure and Function
Dr. Mike describes skeletal muscle as attached to the skeleton, allowing for voluntary movement. He uses the example of the biceps brachii to show how skeletal muscle contraction results in joint movement. Skeletal muscle is consciously controlled (voluntary) and has a cylindrical structure under a microscope. It is also multi-nucleated, meaning it has many nuclei, giving it a high capacity for growth, or hypertrophy.
❤️ Cardiac Muscle: Involuntary but Essential
Cardiac muscle, responsible for pumping blood, contracts involuntarily. Dr. Mike highlights the importance of this feature, as conscious control over heartbeats would be exhausting. Cardiac muscle is branched, has one or two nuclei (uni- or binucleated), and also shows striations similar to skeletal muscle. This muscle type doesn't have the same hypertrophy potential as skeletal muscle.
🌀 Smooth Muscle: Structure and Function in Organ Systems
Smooth muscle, found in the digestive, urinary, reproductive tracts, and blood vessels, contracts involuntarily and lacks striations, appearing smooth under the microscope. It has a spindle-shaped structure and only one nucleus (uninucleated). Its unique arrangement allows for contractions in multiple directions, which is vital for processes like peristalsis, moving substances through the body.
🔬 Striations and Sarcomeres: Muscle Contraction Mechanics
Dr. Mike explains how striations in skeletal and cardiac muscles are due to the arrangement of myosin and actin filaments. These proteins overlap and form sarcomeres, the smallest contractile units of muscle. Myosin heads bind to actin and move along it, shortening the muscle and causing contraction. This organized structure is key for the efficient function of these muscle types.
🧬 Muscle Growth and Hypertrophy
Skeletal muscle's capacity for growth (hypertrophy) is tied to its multi-nucleated structure. More nuclei allow for more protein synthesis, essential for muscle repair and growth. When skeletal muscle is stressed during exercise, growth factors are released, leading to increased protein production and muscle growth. In contrast, cardiac and smooth muscles have less capacity for hypertrophy due to their fewer nuclei.
⚙️ Communication Between Muscle Cells
Dr. Mike describes how muscle cells, especially cardiac muscle, communicate through structures like gap junctions and intercalated discs. In cardiac muscle, electrical signals spread quickly, causing synchronized contractions (a process known as syncytium). This communication ensures that the heart contracts as a unified organ. Skeletal muscle, however, requires individual nerve signals for each cell, while smooth muscle cells contract in a coordinated manner due to their structural organization.
🌀 Peristalsis and Smooth Muscle Contraction
Smooth muscle's ability to contract in multiple directions is vital for moving substances through hollow organs. Dr. Mike compares this action to squeezing a tennis ball through a stocking, where the muscle shortens the tube and narrows its diameter. This process, known as peristalsis, allows smooth muscle to propel substances through organs like the intestines or blood vessels.
🔗 Structural Differences Between Muscle Types
Dr. Mike concludes by summarizing the structural differences between the three muscle types. Skeletal muscle cells are arranged in parallel for efficient shortening during contraction. Cardiac muscle cells, due to their branching and gap junctions, work together to contract the heart in unison. Smooth muscle cells, arranged in a mishmash pattern, contract in various directions to facilitate movement through tubular organs.
📚 Recap and Social Media Outro
Dr. Mike wraps up the video by reviewing the main differences between skeletal, cardiac, and smooth muscles, emphasizing their functions, structures, and the types of movement they control. He encourages viewers to follow him on social media for more educational content and invites them to like and subscribe to his channel for future videos.
Mindmap
Keywords
💡Skeletal Muscle
💡Cardiac Muscle
💡Smooth Muscle
💡Voluntary Movement
💡Involuntary Movement
💡Striations
💡Hypertrophy
💡Intercalated Discs
💡Gap Junctions
💡Sarcomere
Highlights
Introduction of the three types of muscle tissue: skeletal, cardiac, and smooth muscle.
Muscle tissue is one of the four primary tissues of the body, alongside epithelial, nervous, and connective tissue.
Muscle tissue performs mechanical work, enabling movement, blood circulation, and digestion.
Skeletal muscle is voluntary, allowing conscious movement, and is attached to the skeleton to facilitate locomotion.
Cardiac muscle is involuntary and responsible for the heart's rhythmic contractions, pumping blood through the body.
Smooth muscle is also involuntary and found in hollow organs, helping to move substances through the digestive, renal, and reproductive tracts.
Skeletal muscle fibers are cylindrical and multi-nucleated, which allows them to grow through hypertrophy.
Cardiac muscle fibers are branched and either uni- or bi-nucleated, with intercalated discs connecting the cells for synchronized contraction.
Smooth muscle fibers are spindle-shaped and uni-nucleated, lacking the ability to grow significantly due to their single nucleus.
Both skeletal and cardiac muscles are striated due to the arrangement of contractile proteins (actin and myosin).
Smooth muscle lacks striations because its contractile proteins are arranged in a more random, less structured fashion.
Skeletal muscle grows through hypertrophy by synthesizing more proteins in response to stress, which is facilitated by the many nuclei in its cells.
Cardiac muscle cells communicate through gap junctions, allowing for coordinated contraction throughout the heart muscle.
Smooth muscle cells contract in multiple directions, aiding in peristalsis, the movement of substances through tubes like the digestive tract.
The lecture concludes with an emphasis on the structural and functional differences between the three muscle types and how these adaptations suit their respective roles in the body.
Transcripts
hi everybody Dr Mike here in this video
we're taking a look at the three
different muscle types of the body
skeletal cardiac and smooth and we're
going to compare and contrast each of
them
[Music]
importantly we need to begin by talking
about what muscle tissue is it's one of
the four tissues of the body we've got
epithelial we've got nervous we've got
connective and we've got muscle tissue
and the job of muscle tissue is to
perform mechanical work it allows for us
to move whether it's to move our body
consciously whether it's to move the
blood into and out of the heart or
whether it's to move various substances
through our digestive tract our renal
system or our reproductive tract all of
this occurs because of muscles and
muscles are excitable tissue this is
really important for students to
understand excitable tissue there's only
a couple of different excitable tissue
types in the body you've got nervous
tissue endocrine tissue and muscle
tissue now a tissue being excitable
means it has the capacity to do
something it can be excited like me it
can do nothing but when it's excited
something happens so nervous tissue when
nothing's happened it doesn't fire any
signals off but it can be excited to
send what we call an action potential a
signal for communication the endocrine
system when these cells aren't doing
anything nothing's happening but they
can be excited to do something which is
to release hormones into the bloodstream
and muscle tissue when they're not doing
anything they just sit there but they
can be excited to contract and when
muscles contract and shorten they can
help move things around so if it's
skeletal muscle when this muscle
contracts it moves the skeleton and
allows for locomotion when cardiac
muscle contracts it decreases the volume
of these little cavities inside the
heart known as atra and ventricles and
pushes blood around the body and the
smooth muscle that lines the inside
hollow organs of our digestive tract our
renal tract and our reproductive tract
and also our blood vessels when they
contract they help push substances
through the body so that's really
important for you to understand let's
first begin with skeletal muscle
skeletal muscle is muscle that's
attached to our skeleton and generally
speaking these muscles cross joints for
example I've drawn up the biceps brachii
it crosses both the shoulder joint and
the elbow joint and when you excite
skeletal muscle to contract it will
shorten and if it shortens and it
shortens across joints those joints move
so
contract biceps brachii
I get elbow flexion I can track biceps
brachii I get shoulder flexion and this
is the result of skeletal muscle now all
skeletal muscle contracts consciously we
must write that down so it is conscious
let's say voluntary is a better one it's
voluntary
movement
voluntary movement now compare that to
something like cardiac right do you
consciously tell your heart to contract
no thank God we don't because imagine
how much mental time and energy it would
take to constantly tell our heart to
beat once every second it would be
horrible so cardiac muscle is
involuntary and like I said you should
be grateful for that smooth muscle this
is going to be the muscle that lines the
inside of our hollow organs like I said
a digestive tract so our esophagus our
stomach our small large intestines all
the way through and our urinary tract so
our ureters our bladder our urethra and
our reproductive tract and our blood
vessels as well this is all smooth
muscle again you don't tell this muscle
to contract so it contracts in
voluntarily
please
I'll just write involuntary like I did
for the other one so only one is
voluntary contraction that's skeletal
muscle I want you to think about what
these cells look like under a microscope
because it tells you a lot about their
function so if I were to draw up
skeletal muscle and see what it looks
like under a microscope what you'll find
for skeletal muscle is number one it's
shaped like a cylinder compare that to
cardiac muscle if I were to compare
cardiac muscle under a microscope what
you'll find is that it's branched
and then if I were to compare that to
smooth muscle under a microscope it
has this shape to it like a spindle
shape like an eye all right so that's
the first thing that's how they look
under the microscope quite different
than nuclei we must talk about the
nuclear because it's very important
particularly for skeletal muscle now the
nuclei we know houses DNA and if we look
at skeletal muscle you're actually going
to find that it is multi
nucleated multi-nuclear let's write this
down let's write down the fact that it
is
cylinder shaped
let's write down the fact that cardiac
is Branched
and write down that smooth muscle is
spindle shaped
and then let's write down that skeletal
muscle is multi
nucleated
has many nuclei
if we compare that to cardiac it's uni
or by nucleated and it's usually found
right in the center so let's write uni
or sometimes by nucleated
and then let's compare this to smooth
muscle which is uni nucleated
now again and it's sitting right in the
center
what's so important about look
the nuclei well it's really important
for skeletal muscle think why which of
these three muscles or muscle types do
you think has the capacity to grow most
hypertrophy is the term that we use for
muscle growth or tissue growth really
it's skeletal muscle you go to the gym
you lift weights the whole reason why
muscle grows or skeletal muscle grows is
because you expose it to stress and that
stress is a heavy load and that muscle
goes this is difficult I don't want it
to be this difficult next time so I'm
going to release growth factors and I'm
going to stimulate the synthesis of more
proteins to allow for muscle contraction
to occur we know that proteins are made
from the DNA in our nuclei DNA gets
transcribed into RNA RNA gets translated
into amino acids which fold into
proteins and proteins can be used for
contraction and growth and that's what
happens with skeletal muscle so the more
nuclei the more capacity you have for
hypertrophy and growth and that's why
skeletal muscle has so many nuclei our
heart has less of a capacity hence why
it's uni or binucleated and as smooth
Muscle really doesn't have the capacity
for hypertrophy hence why it's only
uni-nucleated let's talk a little bit
about their appearance as well because
what you're going to find is down the
microscope skeletal muscle
has these Stripes like these tiger
looking Stripes to it so does cardiac
cardiac has these Stripes as well
we call these Stripes striations so
let's write this down so this is
striated
skeletal muscle this is also striated
this is cardiac muscle but smooth muscle
now this is where the name comes from
right skeletal muscle makes sense it's
attached to the skeleton cardiac muscles
easy It lines the ventricles and atria
of our heart smooth muscle tells you
nothing about where it is but about what
it looks like under the microscope
smooth muscle looks smooth it does not
have those striations so let's write
this down let's write striations
and then let's put a
cross through it no striations what are
these striations these striations are
the protein
microfilaments that allow for
contraction to occur so if I were to
take either cardiac sorry cardiac or
skeletal and have a look at it in a bit
more detail it's going to look a little
bit like this
you're going to have two major types of
proteins you're going to have
what's called myosin
and this myosin has these little Golf
Club looking heads to them like this
these little arms and golf club looking
heads
and they need to bind to the second
protein and that second protein is
called actin so let's draw up some actin
so here's some actin
now we're going to have these things
called Z discs over here
and what was actually what we've
actually just drawn up here is what we
call a sarcomere so this actual thing
here called a sarcomere
is actually the smallest contractile
unit of muscle what happens is the mice
and heads bind to the actin they walk
along it and they shorten the whole
thing that's contraction if you shorten
a contraction shorten and contract this
you're going to shorten and contract the
muscle tissue so you've got the myosin
which is the blue I'll write that down
for you we've got the myosin
and you've got the actin
now I was saying to you about the
striations what are the striations well
can you see here that you've got Parts
where both proteins overlap so you've
got an area here no overlap
here overlap no overlap overlap no
overlap when you look at that under a
microscope you get stripes the areas of
overlap look darker and they're the
striations which tells you that in both
skeletal muscle and cardiac muscle actin
and myosin are arranged in this fashion
for contraction to occur but when we
look at
smooth muscle it's not arranged in this
fashion in and the reason why is this
because they're arranged in series and
parallel right so basically take this
sarcomere and go boom boom boom boom and
then go boom boom boom boom and add them
in series and parallel so they're all in
the same direction so that when they
contract the whole thing shortens which
means when skeletal muscle contracts the
whole thing
shortens when cardiac muscle contracts
the whole thing
shortens but the difference here was
smooth muscle is that they're not
arranged in series and parallel they're
arranged in what seems to be this
mishmash different shape and if it's
arranged in this mishmash shape you
don't get these pattern striations and
why would we want our smooth muscle to
be arranged in a weird way because we
don't just want contraction of our
smooth muscle to go like that we want
contraction of our smooth muscle to go
in many directions
why well because smooth muscle is not
just straight like skeletal muscle where
we want it to shorten like this and bend
the joint or cardiac muscle where we
wanted to shorten and contract over
ventricle we have smooth muscle lining a
tube and so if we've got a tube like
this
what you want is you want to narrow the
diameter of that tube similar to what
happens here but you also want to
shorten the length of the tube and this
is how things move through if you were
to get a tennis ball put it into a
stocking and you were to squeeze that
tennis ball through the stockings what
you're doing is you're narrowing the
diameter but you're also shortening the
tube and that's peristalsis that's how
things move through tubes and it can
only happen if the uni uh sorry if the
smooth muscle cells have their
contractile proteins arranged in what
looks like a mishmash sort of random way
so hopefully that makes sense to you so
we've got voluntary fiskeletal
involuntary for cardiac involuntary for
smooth we've got multi-nucleated for
skeletal we've got uni or binucleated
for cardiac and we've got uni nucleated
for smooth we've got uh cylinder shaped
for skeletal branched for cardiac and
we've got spindle shaped for our smooth
muscle all right what's the next thing
we need to look at we need to have a
look at
how are they connected to one another so
what you'll find here for the skeletal
is that they're simply just sitting on
top of each other like parallel right so
you're going to have
there's one there
there's one there
there's one there right
when we look at cardiac it's going to be
attached like this
because it's branched it wants to be
attached to other ones like this
so you've got all these branches
attached to each other
now why is this the case this is
important because
little for a second because because it's
rained arranged in parallel it's like
that on purpose take them you're going
to have the it arranged for the biceps
for example these big long
cylindrical cells like this right
like that I know my lines aren't very
straight but it's like that so that when
it contracts
it shortens like that that's easy but
the branching because it moves around
these ventricles and Atria they're
actually connected
through little gaps
called Gap Junctions you've got these
intercalated discs that hold each cell
together intercalated discs they hold
each one together and then you've got
these Gap Junctions let's write this
down you've got intercalated discs
enter
collated
discs right which hold things together
and then you've got Gap Junctions
which allow for communication
talk to each other
now why do we want them to talk to each
other here's the thing you probably are
aware that when a heart contracts you
don't just contract one part of the
heart muscle you contract all of the
heart muscle but the stimulus for
contraction begins in one spot the
sinoatrial node it begins at around
about
up here
an electrical signal gets sent
in this fashion
around the tissue now the electrical
signal needs to spread through the
muscle now it spreads through these Gap
Junctions so if you start an action
potential or you know sodium jumping
into this cell it gets the spread to
this one and spreads to this one so when
that contracts that contracts and then
that contracts and it contracts in what
we call a sensation it means that if you
stimulate one muscle cell to contract
all the rest will contract that's not
the same here you need a different motor
neuron innervating each of these muscle
cells if I have a motor neuron coming
down it needs to innovate that one it
needs to innervate that one it needs to
innovate that one to tell it to contract
not the case here you only need to
innovate this first one
and it spreads the signal to the rest
and they all act as one when all muscle
cells act as one we call that a
sin session
spelled that wrong see I shouldn't
shouldn't talk at the same time sin
I've probably spelled it wrong again but
anyway the term is sensation I promise
you that it's just that my spelling is
pretty poor
and then when we've got smooth muscle
they're going to be connected as well
like this
so I've got a spindle I'm going to have
another spindle
I'm gonna have another spindle
we're gonna have another spindle
I'm gonna have another spindle like that
and again it's so they contract in
multiple directions to help move things
through
all right so these are the similarities
and differences between skeletal cardiac
and smooth muscle and I hope that it
helps hi everyone Dr Mike here if you
enjoyed this video please hit like And
subscribe we've got hundreds of others
just like this if you want to contact us
please do so on social media we are on
Instagram Twitter and Tick Tock at Dr
Mike tadarovich at
d-r-m-i-k-e-t-o-d-o-r-o-v-i-c speak to
you soon
foreign
تصفح المزيد من مقاطع الفيديو ذات الصلة
Introduction to the Muscular System - Animated Tutorial | Complete Anatomy
Types of Tissue Part 3: Muscle Tissue
Three Types of Muscle Tissue (Skeletal, Smooth, Cardiac) Anatomy Compilation Review
BIOLOGI Kelas 11 - Sistem Gerak Manusia (PART 2) | GIA Academy
Big Guns: The Muscular System - CrashCourse Biology #31
The Muscular System Explained In 6 Minutes
5.0 / 5 (0 votes)