NPB 101 Exam 1

What is Physiology

An old field of study done by many intellecturals (Aristole first described functions in all living organisms, Galen of Pergamon believed that the brain controlled all living functions)…USED SCIENTIFIC METHOD (made observations, asked questions, propsed hypothetical mechanisms, used other sciences to investiagte physiology

Define Physiology

Study of Body’s Function

What is Mechanistic Approach

We propse several hypothetical mechanisms to explain body functions…each mechanism is tested experimentally

Gradients drive movement of _____

molecules

What is Homeostasis and why is it maintained?

body organs operate in order to maintain a relatively constant internal environement…it is maintained because disturbances in this internal environment can disrupt cellular function and life function

What is the internal environment

Fluid (ECF, plasma, brain)

Nearly every organ system homeostatically regulates body parameters:

Body temperature, Blood Glucose, Gas concentrains in blood, Concerntration of water, electrolytes, salt and body pH

How do you correct the disturbance, what is homeostatic reflex? Describe the image.

Negative Feedback Loop is a process that counteracts a disturbance by initiating responses that restore the internal environment to its set point.

If you have a high body temperature, your receptor will detect this disturbance and sends information to the central processor through your afferent pathway. The central processor will compare this information to your set pt. value and determine what decision to make. It then sends information to the effector organ (sweat glands) through your efferent pathway. The efferent pathway will activate the effector organ to produce sweat until your body returns to the set pt.

*it is called negative feedback because it produces a negative affect on the intital disturbance

What is the purpose of homeostasis?

to correct the disturbance (although sometimes not completely)

-reflexive/involuntary

If you are in a diseased state, the set pt. will shift…what happens?

we will homeostatically regulate to that new pt.

What is the heirarchy of body organization

chemical/molecular

cellular

tissue-level

organ-level

organ system-level

what is the primary unit of life?

cells (the human body has 37.2 to 70 trillion) (200 different types)

What is the Cell Membrane?

the cell membrane acts as a wall to separate the ECF from the ICF. Structurally, it is made of the phospholipid bilayer (the hydrophilic head (negatively charged and polar) and hydrophobic tails (uncharged and nonpolar))

What is cytoplasm

liquid portion of the cell

What is the cytoskeleton

alot of protein strands that provide shape and strength

What is an organelle and what are the two kinds?

an organelle is a little organ. the two types are the membrane bound ones (Endoplasmic Reticulum and the mitochondria) and non-membrane bound ones (ribosomes)

What are tissues made of and how many types are there?

Tissues are a collection/grouping/cluster of cells that work together…there are 4 types of tissues: muscle tissue, nervous tissue, epithelial tissue, and connecting tissue

describe muscle tissue

Role: Contraction → shorten, generate force, generate heat

Muscle Tissue (3 types)

1. Skeletal (skeleton)

   1. voluntary

   2. striated

2. Cardiac (heart)

   1. involuntary

   2. striated

3. Smooth (hollow organs)

   1. involuntary

   2. unstriated

describe nervous tissue

Role: communication, processing, neuron = actively communicates (propogates the Action Potential)

describe epithelial tissue

Role: serves as covering over organs (ex: kidney in nephron, skin)d

describe connecting tissues

adipose tissue = storage site for lipids

bone tissue

cartilage

describe organs

organs are made up of two or more tissues that work together

organs are organized into _________

organ systems

define organ systems

the group of organs perform activites that accomplish specific tasks (we have around 11-12 different organ systems)

All organ systems are involved in homeostasis except ____

Reproductive system

circulatory system

heart, blood vessels, blood

digestive system

mouth, pharynx, esophagus, stomach, small intestine, large intestine, salivary glands, exocrine pancrease, liver, gallbalder

respiratory system

nose, pharynx, larynx, trachea, bronchi, lungs

urinary system

kidneys, ureters, urinary bladder, urethra

skeletal system

bones, cartilage, joints

muscular system

skeletal system

integumentary system

skin, hair, nails

immune system

lymph nodes, thymus, bone marrow, tonsils, adenoids, spleen, appendiz, and not shown, white blood cells, gut-associated lymphoid tissue, and skin-asscoaited lymphoid tissue

nervous sytem

brain, spinal cord, peripheral nerves, and special sense organs

endocrine system

all hormone-secreting tissues, including hypothalamus, pituitary, thyroid, adrenals, endocrine pancreas, gonads, kidneys, pineal, thymus, and parathyroids, intestine, heart, skin, and adipose tissue

reproductive system

male: testes, penis, prostate gland, seminal vesciles, bulborethral glands and associated ducts

females: ovaries, oviducts, uterus, vagina, breasts

membrane proteins provide functions to membranes in two primary ways

1. spanning/transmembrane = span across lipid bilayer at least once, involved in transport

2. peripheral = not embedded in the lipid bilayer, involved in signaling

Roles of membrane proteins

1. ion channels = allow ion movement across membrane

2. transporters adhesion/anchors = can move ions, larger molecules (sometimes need energy)

3. adhesion/anchors = allows cells to stick to each other

4. receptors = bind to signal molecules

5. enzymes = catalyze chemical receptros

for a real cell, which can cross the cell membrane?

1. gases such as CO2

2. water

3. ions, such as K+

4. lipid soluble molcuels

5. all of the above

1. gases such as CO2 (ANSWER)

2. water (only sometimes)

3. ions, such as K+ (never anything charged)

4. lipid soluble molcuels (only if very small)

5. all of the above

what are the two different types of transport across membranes?

unassisted and assisted

describe unassisted transport (simple diffusion)

Unassisted: does not require a membrane protein to move the item

Used by very small molecules, non-polar molecules, gases

*driven by gradients

Passive

*SIMPLE DIFFUSION

gradients favor…

high concentration to low concentration

describe assisted membrane transport (ion channel)

movement of substances with the help of membrane proteins

moves charged ions across membrane

channels are usually ion-specific

create a water-filled pore

do not change their shape while moving item

2 Main Types

1. facilitated diffusion

   1. no energy used

   2. concentration gradient

   3. certain specific binding sites for transported substance

   4. carrier changes shape as it transports the item

2. active transport (2 types) (if no concentration gradient)

   1. Primary = directly uses ATP → ADP + Pi + energy

      1. Na+/K+ ATPase transports 3 Na+ out of cell, 2K+ into the cell

      2. Both are against concentration gradient

   2. Secondary = does not directly use ATP, uses the energy from a gradient created by primary transport

What is a membrane potential?

all living cells exhibit a separation of charge between the intercellular and extracellular fluids…its a voltage = -70mV

Om’s Law

Potential = V or E

Current = I

Resistance = R

Om’s Law = E = IR; I = DeltaE/R

at rest, membranes are more permeable to ___

K+

What is Nernst Equation?

predicts the potential at equilibrium (tells you the voltage at which there is no net movement of that ion across the membrane because the electrical force exactly balances the concentration gradient)

Ex = 61/z mVlog[x]outside/[x]inside

Inside a real cell, describe the concentratino of Na+ and K+

Na+ is in the ECF

K+ is in the ICF (high permeability)

When a cell is at rest, neither K+ or Na+ is at

Equilibrium (energy is needed to keep at rest → Na+/K+ ATPase)

What is the GHK equation

used to calculate resting membrane potential of a real, living cell (don’t need concentration of ions)

Depolarization

cell becomes more electropositive

hyperpolarization

cell becomes more electronegative

graded potential

change in membrane permeability

threshold

its a membrane permeability, when we depolarize to threshold → we get an A.P.

repolarization

return back to rest

describe graded potential

some cells experience small changes to the resting membrane potential

• can occue in response to triggering events (stimuli detected by the cell, signal factors binding cell receptors

small change in Erest (only occur between resting potential and threshold)

• receptor potential

• post-synatic potentials

• localized to the place that receives the input

• the size of the graded potential is proportional to the triggering event magnitude

graded potentials can _____ passively as an ________

spread, electrical current (charge dies out over distance)

describe Action Potential

occurs when the cell depolarizes to threshold, usually much larger than a graded potential, it’s a stereotyped transiet change in membrane potential (once the A.P. occurs, it always looks the same)…A.P.’s create local current that regenerates the AP

the depolarization happens in response to alot of ____ voltage gates opening

Na+

Action Potential is ___ in duration

Quick (1-3msec), large (~100mV), fast

______ channels are key to the AP

Gated

at rest, does the inactivation gate block or not block the channel?

not block

with depolarization, what does the inactivation gate do?

slowly blocks the channel’s pore

the inactivation gate is how we control ____

postive feedback

explain this (positive feedback and negative feedback)

positive feedback = opening of voltage-gated Na+ channels → increased PNa+ → increased flow of Na+ into the cell → depolarization of membrane potential → continues to open voltage-gated Na+ channels

negative feedback = opening of voltage-gated K+ channels → increased PK+ → increased flow of K+ out of the cell → repolarization of membrane potential → opening of voltage-gated K+ channels

upswing of the action potential involves 2 gates

1. activation gate

   1. resting cell: activation gate is closed

   2. depolarizatioin: activation gate is open

2. inactivation gate

*positive feedback mechanism

the peak of the action potential

as cell depolarizes, the inactivation gate will CLOSE

The V-gated K+ channel is _____ at rest

closed

• depolarization = slowly activates

• dramatically increases K+ permeability: ~300X over resting Na+ permeability

absolute refractory period

period of time right after an AP when a neuron cannot fire another AP…while Na+ channels are inactivated, they cannot reopen until the membrane returns to resting potential (ensures one-way propogation)

relative refractory period

short period of time after the absolute refractory period when a neuron can fire another AP, only if the stimulus is stronger than normal

• V-gated Na+ channels have converted to closed state

• V-gated K+ channels are still open → membrane is more negative (hyper polarized)

• important for Cardiac muscle (has a long refractory period)

  • prevents ventricular fibrillations

  • ensures that ventricular contractions always follow atrial contractions

AP do not travel, they spread as a _____

Current

• lateral spread of current is necessary to bring the “quiet” adjacent region to threshold, activates V-gated channnels which induces depolarization

• APs propogate in one direction

Myelin can increase ______ of AP

velocity

• unmyelinated neurons conduct at 0.5 to 10 m/sec = too slow

• can increase velocity by adjusting axon diameter (myelin)

what are glial cells?

Support cells in the nervous system

make up the largest proportion of cells in the CNS

Astrocytes oligodendrocytes, microglia, and ependymal cells

1. Schwann Cells - located in the PNS

2. Oligodendrocytes - located in the CNS

Basically make up the myelin → wrap around axon

what is saltatory conduction in neurons

fast jumping of electrical impulses along myelinated axons

• jumps from one node of ranvier to the next

• nodes of ranvier = small gaps between myelin segments where the axon membrane is is exposed and voltage-gated Na+ and K+ channels are concentrated

There is gap between the neuron and target, the AP cannot jump across the gap…what is the gap called?

Synapse (two types)

1. chemical

   1. more common

   2. electrical signal → release of neurotransmitters that can cross the synaptic cleft

   3. slower

2. electrical

   1. less common

   2. ions flow directly through gap junctions

   3. faster

How does the chemical synapse work?

1. an AP travels down the axon to the axon terminal of the presynaptin neuron

2. calcium channels open → Ca2+ ions rush in

   1. caused by depolarication

3. neurotransmitter is released

   1. Calcium triggers vesicles filled with neurotransmitters to fuse with presynaptic membrane

   2. neurotransmitters are released into the synaptic cleft (exocytosis)

4. neuotransmitters bind receptors

   1. neurotransmitters diffuse across the synaptic cleft

   2. they bind to specific receptros on the postsynaptic membrane

5. ion channels open or close

   1. excitatory neurotransmitters → open

   2. inhibitory neurotransmitters -→ close

Post Synaptic Potentials

1. EPSPs = makes the postsynaptic neuron more likely to fire an AP. Causes depolarization

   1. Na+ influx or Ca2+ influx

2. IPSPs = makes the neuron less likely to fire an AP. Causes hyperpolarization

   1. Cl- influx or K+ efflux

*Graded = variable in strength, can summate

Divergence

one cell influences many others

Convergence

one cell is influenced by many others

temporal summation

same synapse fires rapidly over time (increase frequency of input)

spatial summation

input from 2 or more PSP neurons to induce a response

how does the electrical synapse work?

the signal passes from the presynaptic to postsynaptic cell through gap junctions

what can pass through gap junctions?

APs (travel fast ususally in muscular tissue)

astrocyte (type of glial cell)

most common type of glial cell → helps form the blood-brain barrier

ependymal cell (type of glial cell)

produces cerebral spinal fluid

What are neurons?

excitable cells that propogate APs

there are 3 types of neurons, what are they?

afferent neurons, interneurons, efferent neurons

most neuronal processes are bundled into ____

nerves (vagus nerve, tibial nerve)

The Nervous System is well protected by

Bony cranium, the meninges

• covers the CNS

• Dura Mater (outer)

• Arachnoid Mater (middle)

• Pia Mater (inner)

What is the cerebrospinal fluid

In the ventricles, surrounds the CNS, and in between the layers of the Meninges

• Functions as a shock absorber, allows exchange between the Brain ECF and blood

• Created by the choroid plexus in the ventricles

Why is the Blood Brain Barrier important?

It prevents molecules from entering the Brain ECF

• most of the capillaries outside of the CNS are “leaky”, but most capillaries inside of the CNS are not “leaky”

  • they are tightly regulated with tight junctions and transport mechanisms

  • astrocytes form another barrier for some substances

  • substances only enter the brain via transport processes through endothelial cells or astrocytes (glial cells)

describe the forebrain: cerebral hemisphere

the largest part of the forebrain: cerebrum/cerebral hemisphere

• high cognitive function

• two hemispheres

• the cerebral cortex

  • the outermost layer of GRAY MATTER = where the cell bodies are

  • Lots of Gyri, sulci

  • Cortex sits on top of WHITE MATTER = mainly made up of axons

What is the gray matter mostly made up of?

Cell bodies

where does the cortex sit atop?

White Matter

What does the gray matter encompass?

Cortex, Cerebral Nuclei

What does the white matter encompass?

inner white matter, corpus callosum, internal capsule

How many lobes are in the cerebral cortex and what are they?

5 Lobes: Frontal, Temporal, Parietal, Occipital, Insular

Much of the Cerebral Cortex Lobes functionally is ______

Lateralized meaning that the brain’s hemispheres are not functionally identical

What is Broca’s Area for

speech formation

What is Wernicke’s Area for?

Speech Understanding