Biol 307 Human Physiology Chapters 5 and 8

Extracellular Fluid

1/3 of the total water volume. It consist of interstitial fluid and blood plasma.

Interstitial Fluid: Extracellular Fluid that surround cells and between the cells

Blood Plasma: Liquid Matrix of blood and is found inside the circulatory system

Osmolarity

osmol/L the number of osmotically active particles

Osmolality

concentration expressed as osmoles of solute per kilogram of water

Hypersomatic

When one solution has a higher concentration over another solution

Hyposomatic

When one solution has a lower concentration over another solution

Isomatic

Equal concentrations within two solutions

Osmosis

The movement of water across a membrane in response to a solute concentration gradient

Penetrating Solutes

Solute particles that can’t cross the cell membrane

Passive Transport

Does not require an input of energy other than the potential energy stored in a concentration gradient

Active Transport

Requires outside energy such as ATP to move through a gradient

Concentration Gradient

A difference in the concentration of a substance between two places

Channel Protein

Create a water filled pore between the cell membrane

Carrier Protein

A protein that binds to a substrate they carry

Cotransporter

A carrier that moves more than one kind of molecule at a time

ATPase

Primary Active Transporters; also known as pumps are enzymes that hydrolyze for a designated purpose. An example could be to move molecules against their concentration gradient

Saturation of a transporter

It’s a point where carrier transporters are filled with substrates and are working at their maximum rate

Endocytosis

When the cell indents ligands with receptors and creates vesicles coated with clathrin that contain contents that can’t diffuse through the membrane

Exocytosis

When lipophobic membrane vesicles come from the cell membrane to remove contents within the cell

Electrochemical Gradient

The combination between an electrical and chemical gradient

Equilibrium Potential

The membrane potential that opposes the concentration gradient

Depolarize

When the potential difference becomes more positive

Hyperpolarize

When the potential difference becomes more negative than the resting potential

Extracellular Fluid and Intracellular are in

equilibrium with respect to total osmolality

Adult humans are what percentage of water?

45-60% water depending on age and sex

Osmolality of human body fluid is between the range of

290-300 mOsm

Water will move where

to the area with the higher osmolarity regardless of the concentration

What are examples of of molecules that can and cannot diffuse easily through a membrane

Easy diffusion: Oxygen, Butyric Acid

Difficulty with passive diffusion: Glucose, Epinephrine, Insulin

What two factors are diffusion dependant on?

Molecule size and Lipid solubility

What is the difference between simple diffusion and facilitated diffusion?

Facilitated diffusion uses a mediator called a mediated transport so that the molecule can move through the cell membrane.

Simple diffusion means the molecule can move through the membrane without the assistance of another molecule

What is the difference between simple/ facilitated diffusion and active transport?

Active transport requires energy such as ATP while simple/facilitated diffusion do not need energy

What is the difference between and channel protein and a carrier

A carrier moves in and out of the cell with the protein while a channel stays within the membrane

Primary active transport vs secondary active transport

Primary active transport: Uses energy directly from ATP to push a molecule against its concentration gradient

Secondary active transport: Uses the potential energy stored in the concentration gradient of one molecule going down to push the other molecule against its gradient

Most ion channels are…

gated and apart of a lot of physiology

Secretion

From the extracellular fluid to the lumen of the intestine

Absorption

From the lumen to the extracellular fluid

Glucose needs a

carrier to cross the cell membrane. glucose needs to be phosphorylated inside the cell so that the concentration gradient can pull glucose

The membrane potential=

the voltage across the membrane; animal cells maintain an internally negative membrane potential

Nernst Equation

61 log ion out/ ion in

afferent neurons

neurons that carry information from sensory receptors; sensory nerves

efferent neurons

neurons that carry motor information from the cns to muscles and glands; motor nervers

mixed nerves

Neurons that can do both afferent and efferent activitites

dendrites

thin branches connected to the cell body that receive incoming information from neighboring cells

Interneurons

neurons that lie entirely within the central nervous system

axon hillock

region of axon where it joins the cell body

glial cells

support cells

myelin

a substance composed of multiple concentric layers of phospholipid membrane

nodes of ranvier

segments of the axon not covered in myelin leaving tiny gaps

voltage gated ion channel

respond to changes in the cell’s membrane potential

graded potential

variable-strength signals that travel over short distances and lose strength as they travel through the cell. they are used mainly for short distance communication

action potential

very brief, large depolarizations that travel for long distances through a neuron without losing strength. their function is rapid signaling over long distances

refractory period

represents the time required for the Na+ channel gates to reset

EPSP(excitatory postsynaptic potential)

Depolarizing graded potentials that make a neuron more likely to fire an action potential

IPSP( inhibitory postsynaptic potential)

Hyperpolarizing graded potentials that make a neuron less likely to fire an action potential

Structurally what is the difference between the CNS and the PNS?

The CNS consist of the brain and the spinal cord. The PNS consist of sensory neurons and efferent neurons

Explain why the sodium equilibrium potential (E_Na) and the potassium equilibrium potential (E_K) are different

The equilibrium potential for sodium differs from potassium because of their difference in permeability across the membrane and concentration. Specifically, because the membrane is more permeable for potassium to enter and exit the cell the resting membrane potential is closer to E_K.

Why won’t action potential go backwards

The refractory period prevents sodium voltage gated ion channels from opening up to the action potential of another channel. Once the refractory period ends, the channels will reset back to their original form

a single action potential doesn’t significantly change…

ion concentrations across the membrane

Differentiate structurally and functionally between ionotropic and metabotropic neurotransmitter receptors

Ionotropic: Receptor-channels mediate rapid responses by altering ion flow across the membrane

Metabotropic: Neurotransmitter receptor that acts through a second messenger system an example is GCPR

Several major neurotransmitters

Epinephrine, Glutamate, Norepinephrine, Acetylcholine, Histamine, Amino Acids

Explain why a depolarizing PSP is excitatory (an EPSP) and a hyperpolarizing PSP is inhibitory (an IPSP)

EPSP make the inside of a cell more positive, simulating an action potential

IPSP make the inside of a cell more negative, reducing the chances of having an action potential