NPB 101 M1

Define homeostasis

body organs operate in order to maintain a relatively constant internal environment

What is the internal environment?

ECF, blood plasma

What are the steps for correcting a disturbance in homeostasis?

homeostatic reflex

1. disturbance 2. receptor detects it 3. AP goes through afferent pathway 4. CPU (central processing unit) 5. compare the value to the set point 6. AP through efferent pathway 7. AP to effector organ 8. body induces effect

What are the major principles in physiology?

1. body functions follow the laws of chemistry and physics

2. cells, tissues, and organs interact/work together in a coordinated fashion

3. cells, tissues and organs communicate with each other

4. body fxns are usually regulated by 1 or more controllers

5. gradients drive movement of molecules

6. homeostasis

Is the parameter for body fxns at one set point?

no, there is small variance

What are membrane bound organelles?

mitochondria, chloroplasts, lysosomes, Golgi, vacuoles, ER

What are non membrane bound organelles?

ribosomes, cytoskeleton, centrosome, proteasomes

What muscle tissue is striated?

skeletal and cardiac muscle

What does muscle tissue do?

can contract to generate movement, force, and heat

What are supporting cells outside a neuron?

astrocytes which is a sub type of most neuron supporting cells : glial cells

What does epithelial cells do?

cover surfaces to protect, transport, thermogenesis, and secretions

What are the two types of epithelial tissue structures?

epithelial sheets and secretory glands

What are the types of muscle tissue?

skeletal, cardiac, smooth

Examples of connective tissue

tendons, bone,

how would you describe homeostasis?

dynamic

What are things that are homeostatically regulated?

1. conc of nutrients

2. conc of gas O2/cO2

3. conc of waste prods

4. pH

5. conc of water, salt, + others

6. V + P

7. temp

What are the two ways membrane proteins are associated?

spanning/transmembrane or peripheral

What are functions that membrane proteins provide to membranes?

fluid behavior, can be anchored to phospholipid, can be anchored to other membrane proteins or cytoskeleton

What is unassisted transport?

simple diffusion: does not require a membrane protein to move the item

What types of molecules cross during unassisted transport?

small nonpolar molecules (lipid soluble), gases

What causes unassisted transport?

it is driven by gradients

what type of flux does unassisted transport have?

net flux

do ion channels change shape?

not while moving the item

are ion channels passive or active diffusion?

passive/mediated diffusion

are ion channels constantly open?

not always, they can exhibit gating so the channel can only be opened by certain things

what type of diffusion to carrier/transporters display?

facilitated diffusion

what is an example of primary active transport?

na+/K+ ATPase pumo

what type of molecules does primary active transport move?

positively charged ions

When does Na+ and K+ have a high affinity in the protein pump?

na+ has high affinity when the protein faces the ICF and K+ has high affinity when facing ECF (both ions move against their concentration gradients) Na+ high conc in ECF, K+ high conc in ICF

what causes the change in shape of the carrier protein?

phosphorylation/dephosphorylation which is caused by ATP

Na+/K+ ATPase pump serves as a _________ for secondary active transport

energy source

what is SGLT an example of and what type of transporter is it?

secondary active transport and symport

What is the procedure of the SGLT in the luminal membrane?

Na+ binds first causing an increase in glucose affinity then glucose bind to protein from the lumen (Na+ has a high conc and glucose low) -> shape change causing an opening to the ICF -> Na+ released creating a low affinity for glucose which releases the glucose into the ICF where there is a high conc

does secondary active transport split ATP?

no it does not directly split ATP

What is equilibrium potential?

its when the voltage at which the system forces sum to 0, balance of conc gradient for an ion

what is membrane potential?

the difference in electric potential across cell mem

What is resting membrane potential?

The constant membrane potential present in the cells of nonexcitable tissues and those of excitable tissues when they are not producing electrical signals

how does the na/k atpase effect the membrane potential?

it makes the inside of the cell more negative bc 3na are leaving with only 2k coming in

- has an indirect way of effecting mem potential bc the role it plays in creating the conc gradient contributes to mem potential

whats the nernst equation used for?

it predicts the potential at equilibrium

What are graded potentials?

local changes in membrane potential that occur in varying grades or degrees of magnitude or strength.

do graded potentials die out over distance?

yes

what are some triggering events that create graded potentials?

stimuli detected by cell or signal factors binding to cell receptors

how do graded potentials spread?

as an electric current

what are the properties of AP?

1. occurs when cell depolarizes to threshold

2. usually much larger than a graded potential

3. its a stereotype (always looks the same) transient change in membrane potential

4. APs create local current that regenerates the AP

stages of AP

1. slow depolarization to threshold

2. depolarization/upswing - rapid

3. repolarization/downswing (a type of hyperpolarization)

4. after hyperpolarization

v gate channels open and activate with ______

depolarization

v gated channels are

______ at e rest

closed

what is the post synaptic potentials SUM?

the excitatory post synaptic potential (EPSP) + inhibitory PSP (IPSP) is summed at the target neuron which could lead to an AP. this occurs when neurons talk via synapse

what is an influx of na+ ions associated with?

depolarization

as cell depolarizes the inactivation cell ______

closes

when are the an+ v gated channels inactivated?

at the peak

AP explained

1. there is a depolarizing triggering event

2. when the mem potential hits threshold, the na v gated channels opens and is activated which creates an influx of an into the cell and the permeability inc for na

3. at the peak the na channel is inactivated therefore closing while the K+ channel (that had been slowly opening since the threshold depolar point) is open and activated causing K+ to leave the cell

4. as the mem potential repolarizes, the na+ channel is reset to a closed position

5. afterhyperpolarization leads to...

6. resting potential where K+ channels are filled closed

what is the absolute refractory period?

is time period when a recently activated patch of membrane is completely refractory (meaning "stubborn," or unresponsive) to further stimulation (an open to fully closed again)

what is the relative refractory period?

during which a second action potential can be produced only by a triggering event considerably stronger than usual (K+ channel open, na+ closed)

Does the relative refractory period create an AP and how big is it?

it elicits an AP, but a smaller one than normal. it requires a strong stimulus

refractory periods are important for coding things like _____

stimulus strength

the cardiac muscle has a ____ refractory period. why?

long bc it prevents ventricular fibrillations and ensures that ventricular contractions always follow atrial contractions

what is the purpose of refractory periods

to make sure the AP moves down the axon and not backwards, not that it can

by increasing the axon diameter it can increase ...

velocity of AP

what is a way to increase velocity?

increase axon diameter and use myelin

how fast do the saltatory conduction take?

10-50 m/s

what are the two types of synapses

chemical - nt mediated

electrical - gap-junction mediated

when there is a synapse what needs to happen to move the AP onto the next neuron?

Ca2+ v gates need to open causing an influx of ca2+ into the axon terminal which leads to the vesicles that hold the NTs fusing with the presynaptic membrane to be released into the synaptic cleft. NTs then bind to postsynaptic receptors

What is target cells response to NTs?

EPSP - occurs with Na+ or ca2+ influx into the cell - depolarization

IPSP - occurs with K+ efflux or cl- influx - hyperpolarization

the graded PSP is a sum of EPSP and IPSP

what is convergence in a neuron?

a single cell is influenced by thousands of other cells.

what is divergence in a neuron?

the branching of axon terminals so that a single cell synapses with and influences many other cells.

temporal summation

referring to time, from 1 neuron, summing of several EPSPs occurring very close together in time because of successive firing of a single presynaptic neuron

spatial summation

occurs at axon hillock, summation of EPSPs originating simultaneously from several different presynaptic inputs

what is able to go through gap junctions?

small ions and molecules, never even touch ECF

what are the functions of the nervous system?

- stimulus transduction into electrical signals (AP)

- processing and integration signals

- generation and control of activities

- homeostatic regulation

- higher cognitive function

- we use all of our brain

what is a part of the CNS?

brain and spinal cord.(includes retina)

what is a part of the PNS?

sensory (afferent) and motor (efferent) neurons

what are glial cells?

support cells that make up the largest portion of cells in the CNS

include: astrocytes, oligodendrocytes, microglia, and ependymal

what are the types of neurons?

afferent (sensory), interneuron (memory), efferent (motor)

what are most neuronal processes bundled into?

nerves

what protects the nervous system?

bony cranium, meninges (tissue layers) - cover CNS, dura mater, arachnoid mater, pia mater

where is cerebrospinal fluid?

between meninges, in ventricles and surrounding CNS

what are cerebrospinal fluid functions?

shock absorber, allows exchange between the brain

ECF and blood

how is cerebrospinal fluid created?

created by choroid plexus in the ventricles

are capillaries leaky in CNS?

no but they are outside of it

Since CNS capillaries arent leaky what does it use to transport molecules?

tight junctions and other transport mechanisms thru endothelial cells or astrocytes

What does the forebrain, hindbrain, and mid brain do?

fore brain - cognitive fxns

mid brain - small in adults

hind brain - controls organs

what is the largest part of the forebrain?

the cerebrum or cerebral hemispheres which have a high cognitive fxn

What does the cerebral cortex consist of?

gray matter on the outside, gyri and sulci (grooves in brain), cortex sits on top of white matter that is made up of axons

what are the five cerebral cortex lobes?

frontal, temporal, parietal, occipital, insular

what does the basal nuclei do?

inhibits unneeded muscle activity while maintaining purposeful movement

what part of the brain does parkinson's disease interact with?

basal nuclei

what is in the deeper cerebral areas?

basal nuclei, thalamus, hypothalamus

what is the thalamus fxn?

first place to receive sensory info and send it out

what is hypothalamus fxn?

homeostasis central controller, regulates sleep and wake

what are the hindbrain regions?

pons and medulla oblongata, cerebellum

what makes up the brainstem?

pons, medulla oblongata, and midbrain

what are pons and medulla oblongata fxns?

sleep regulation, alertness, motor coordination, and basic life fxns like breathing/heart

cerebellum

made up of both hemispheres, divided into 3 parts: cerebrocerebellum, spinocerebellum, vestibulocerebellum

what does the cerebrocerebellum do?

stores motor memories (riding a bike) and helps in planning and initiation of voluntary movements

what does the spinocerebellum do?

coordination of voluntary movements, regulates muscle tone

what does vestibulocerebellum do?

In the spinal cords, what type of cell bodies does it hold?

lower motor neurons and interneurons

what are the fxns of gray and white matter in the spinal cord?

gray matter: largely made up of cell bodies (neurons)

white matter: made up of neuronal processes that either ascend toward the brain or descend down from the brain

spinal nerves contain ______ axons and ____processes/neuronal pathways

efferent and afferent