Anatomy and Physiology Chapter 3 Student Lecture Part 1

All right. So this is my chapter three student lecture video

and let's get started.

First, we have intracellular and extracellular fluids.

Extracellular is going to be outside of the cell.

The cells are submersed in this fluid and it includes interstitial fluid,

blood plasma cerebrospinal fluid and the extracellular matrix.

The sodium concentration is high and the potassium concentration is low.

Then we have intracellular which is inside of the cell.

The intracellular fluid is made of cytosol.

The sodium concentration is low and the potassium concentration is high

following that. Um let's talk about the plasma membrane.

So the plasma membrane is an active

barrier that separates intracellular and extracellular fluid

and it determines what can enter and leave the cell.

So the plasma membrane is uh made of like a lipid bilayer

with a water loving phosphate head

which would be

hydrophilic

and water hating fatty acid tails which would be hydrophobic.

There are also membrane proteins, lipids and carbohydrates.

Um The possible membrane is semi permeable which

means only certain things can pass through.

So what can pass through the membrane?

Only certain substances can easily pass through the plasma membrane,

nonpolar substances uncharged and small

um substances are the ones that can go through easily.

But proteins can help determine whether or not a substance can enter the cell.

So membrane proteins,

there are two types of membrane proteins that

can help determine what enters the cell.

Many or

membrane proteins have many functions.

Integral proteins are embedded into the cell membrane

and they have both hydrophobic and hydrophilic regions.

They function as transport proteins, enzymes and receptors.

But their most important function is transport.

Then we have peripheral proteins which are loosely attached to integral proteins.

And they include um filaments on the intracellular surface for

membrane support

and they function as enzymes and motor

proteins.

So functions of membrane proteins,

they have many functions.

So there's transport receptors for signal transduction, enzymatic activity,

cell to cell joining

cell to cell recognition

and attachment to cyto

skeleton and extracellular matrix.

First transport

proteins that span the membrane can create a hydrophilic

channel that is selective for a particular solute.

Some proteins break apart a TP with water that's called hydrolyzing

and use it as energy to pump sub

substances across the membrane. Like you can see on the picture to the right

using a TP to get substances across the membrane is like an energetic currency.

You kind of have to pay with a TP for something to be able to cross through.

Then we have um receptors for signal transduction,

a membrane protein on the outside of the cell may have

a binding site that fits the shape of a chemical messenger.

When connected

the chemical may cause a change in the shape of the protein

which can lead to a chain of chemical reactions within the cell.

Only a certain type of molecule can attach and it has to be the correct shape.

You can see to

the right here

that that little triangle fits perfectly within there.

So that would be

a binding site.

Um

Membrane receptor proteins serve as binding sites for chemical signals

and they can contact signaling cells that

they recognize on the cell surface.

Some cells binding triggers enzyme activation.

So maybe that little triangle going into that blue rectangle can

signal activation

lips.

All right enzymatic activity.

A membrane protein may be an enzyme with its

active active site exposed in the adjacent solution.

Several enzymes in a membrane can help catalyze steps.

Enzymes are specific to what chemical reaction it wants to do.

Each enzyme will complete a different chemical reaction.

So, digestive enzymes will catalyze the hydrolysis of bonds and food molecules.

So, since it is a digestive enzyme, that is its purpose, that is its function.

All right cell to cell joining.

So

there are different kinds of ways that membrane proteins can

connect. So there is tight junctions, desmosome and gap junctions.

So we have gap junction

off to the left of this photo. Here

we have desma

zone

in the middle

and we have tight junctions all the way to the right.

So for tight junctions,

the integral proteins on nearby cells will

fuse and form an impermeable junction that

uh

encircles the whole cell.

And it prevents most molecules from moving between cells.

Desmosome are rivet like cell junctions formed with when linker proteins or C

herons,

um interlock like a zipper.

The protein is anchored to the cell with a button like

area on the inside of the plasma membrane called a plaque.

And keratin filaments connect the plaques in intercellular

for strength

desmosome are give a little bit more, they are able to move more.

So it reduces the possibility of tearing.

Then gap junctions

um have transmembrane proteins

that form tunnels and they allow small molecules to pass from cell to cell

cell to cell recognition.

There are some glycoproteins that serve as name

tags that are recognized by other cells.

Um and proteins can tell which cells they are by this glycoprotein name tag

and you can tell whether or not they're foreign

or if they are supposed to be there.

Lastly. Attachment to the cytoskeleton and extracellular matrix,

the cytoskeleton and extracellular matrix will anchor to

membrane proteins and this helps maintain cell shape

and it fixes the location of membrane proteins and plays a role in cell movement.

Next, we have diffusion and osmosis.

So since the plasma membrane is semi permeable,

only certain substances can pass through

um substances can pass through using diffusion and osmosis

diffusion and osmosis both fall under the category of passive transport,

which means there is no energy used.

Diffusion

is the natural movement of molecules from areas

of high concentration to areas of low concentration.

There is passive transport,

no energy and active transport uses energy.

So this is an example of passive transport.

As you can see in any of these photos, there is not um or any of the examples to the left,

there is not being any A TP used,

which would be our energetic currency like I talked about before.

So there is simple diffusion where

the molecules just pass through from

uh one side to the other, no energy used.

Then there is this channel

that

uh molecules are passing through no energy used.

And then lastly, there's a carrier protein and there's not energy used.

On the other side of the image,

there is a TP being used in order for molecules to come through

what affects diffusion.

So concentration,

the greater the difference of concentration between two areas,

the faster a diffusion occurs

molecule size. So smaller molecules diffuse faster

and then temperature,

higher temperatures can increase kinetic energy

which results in faster diffusion.

Molecules can move closer together when the heat is increased.

All right. So

facilitated diffusion.

If something is preventing a molecule from crossing the

membrane like being too large or too polar,

it can use a protein or a channel to help it get through.

Um facilitated, basically means that it needs assistance

in order to pass through the membrane.

And with that,

um besides the carrier protein, there are also different types of channels

that go along with that.

So when using a protein, there's no energy use like I said before.

But um

certain hydrophobic molecules,

for example,

glucose amino acids and ions are

transported possibly down their concentration gradient

by carrier mediated facilitated diffusion.

The molecule will attach to a protein and it will change

its shape in order to help it move through the membrane

binding of the molecule causes the carrier to envelop it

like in this image down here to the right.

And

um

it changes shape that allows the molecule to pass through.

So, binding is also limited depending on how many carriers are present.

Then we have channel mediated dis

facilitated diffusion

and that's what we'll move to. So there's different types of channels.

So we have

three different types of channels which are

ligand

gated channels which are closed at rest and open

in response to binding of a specific chemical or

ligand

to a specific receptor.

Then we have voltage gated channels that are closed at

rest and respond to changes in voltage across the membrane.

And then we have mechanically gated channels that are open

and closed in response to mechanical stimulation

such as pressure stretch or vibration.

Next is osmosis.

So osmosis is the movement of a solvent, usually water not molecules,

osmolarity measures the concentration and of the total

number of salute particles in a solvent.

When salute concentration goes up, water concentration goes down and that

is vice versa.

Water moves by osmosis from areas of low

salute concentration

to high salute

concentration.

All right. So we have

different types of pressures. So we have hydrostatic pressure,

which is the outward pressure exerted on the cell side

of the membrane

caused by increases

in volume of the cell due to osmosis

osmosis.

Then we have osmotic pressure

which is inward pressure due to the tendency of water

to be pulled into the cell with higher osmolarity.

So more solvent in there.

So back to hydrostatic, it's the pressure of water, water building up.

Since the water wants to go from high concentration to low concentration

for osmotic,

um the more solutes inside the cell, the bigger pull on water to enter,

resulting in a higher osmotic pressure inside the cell.

Since the solvents want to go from high to low.

All right, for tonicity.

So,

tonicity is the ability of a solution to change shape

or tone of cells by altering the cells,

internal water volume.

So first we have an isotonic solution which is to the right of the image

and it has the same osmolarity as the inside of the cell.

The volume is not changed at all whatsoever.

Then we have a hypertonic solution which is to the left of the image

and it has a higher osmolarity than inside the cell.

So water flows out of the cell resulting in shrinking

or crenation.

As you can see in the image,

then we have

a hypotonic solution that has a lower osmolarity than inside of the cell.

So the water flows into the cell

which causes the cell to swell

and that could

lead to cell bursting

or lying.

All right. So now on to active transport,

there are two types of active transport.

So there's active transport and vesicular transport. Both require a.

Anatomy and Physiology Chapter 3 Student Lecture Part 1

Chapters

Audio TranscriptAuto-generated