Physiology Exam Review #1 Flashcards by Bethany Koehle

Explain Negative Feedback Loops

Receptors detect change in the body and send the information to the Integrating center which will assess change around a set point and send instructions to the Effector (muscle or glands) which makes the appropriate adjustments to counter the change from the set-point

Moves in the opposite direction from the change
Makes the change from the set-point smaller
Reverses the change in the set-point
A continuous process, always making fine adjustments

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Explain Positive Feedback Loop

The end product in a process stimulates the process
The action amplifies the changes that stimulated the effectors
Positive feedback could not work alone, but does contribute to many negative feedback loops
Forming a blood clot is a process of positive feedback loop
Strength of uterine contractions is regulated by positive feedback loop

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For this to occur, the membrane must be selectively permeable
There must be a difference in the concentration of a solute on the two sides of the membrane
Water moves from higher concentration to lower concentration
Diffusion of solvent instead of solute

Osmosis

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Found in the kidneys, eyes, lungs, salivary glands, and the brain
Specific proteins present in the plasma membrane that serve as water channels and permit osmosis

Aquaporins

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permit the passage of ions

ion channels

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Ions that are osmotically active

polar molecules
glucose
ions

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does not require energy and moves from higher to lower concentration

passive transport

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requires the expenditure of energy and sometimes cells need to move molecules against their concentration gradient (lower to higher concentration)

active transport

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Attached to bones
Makes up 40% of body weight
Responsible for locomotion, facial expressions, posture, respiratory movements
voluntary
striated

skeletal muscle

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in the walls of hollow organs, blood vessels, eye, glands, uterus, and skin
propel urine, mix food in digestive tract, dilating/constricting pupils
regulating blood flow
no sarcomeres (non-striated)

Smooth muscle

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striated
myosin and actin filaments form sarcomeres
fibers are short, branched, and connected via gap junctions

Cardiac muscle

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plasma membrane of skeletal muscles

sarcolemma

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Light bands are also known as

I bands

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Dark bands are also known as

A bands

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dark lines in the middle of the I bands

Z disks

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site where a motor neuron connects to a muscle fiber

neuromuscular junction

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postsynaptic membrane of the muscle fiber

motor end plate

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contains only thin filaments, primarily of the protein actin

I bands

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contains all of the thick filament with some thin filament overlap; thick filament is the protein myosin

A bands

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center of the A band with no thin filament overlap

H band (H zone)

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lines found in the center of each I band

Z discs

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basic subunit of striated muscle contraction that runs from Z disc to Z disc

sarcomere

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anchor which Actin is attached at

the Z discs

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found in the center of the A band; helps hold myosin

M line

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a protein that runs from the Z disc to the M line through center of myosin. Stabilizes it, prevents overstretch, and creates elasticity

titin

each somatic motor neuron, together with all of the muscle fibers that it innervates is known as a

motor unit

which motor units are used the most often

the smaller motor units

when contractions of greater strength are required, larger and larger motor units are activated in a process known as

recruitment of motor units

Describe steps of Na+/K+ pump

- found in all body cells and half of daily calories are utilized - 3 Na+ out of the cell and 2 K+ into the cell - 3 Na+ from the cytoplasm move into the pump and bind - ATPase activated to hydrolyze ATP to ADP and P which blocks both openings - ADP released causing a shape change that allows 3 Na+ to exit pump to outside of cell - 1 K+ enter carrier from the outside, releasing P - Pumps returns to original shape and release 2 K+ to the inside

Characteristics of resting membrane potential

- resting potential of -70mV - established by large negative molecules inside the cell - sodium potassium pumps - limited permeability of the membrane to positively charged inorganic ions - at rest, high concentration of potassium inside the cell and sodium outside of the cell

emergency situations; "fight or flight"

sympathetic nervous system

normal functions; "rest and digest"

parasympathetic nervous system

wraps of this cell make up the myelin sheath in the PNS

Schwann cells

the myelin sheath is produced by these cells in the CNS

oligodendrocytes

produces the myelin sheath but not a neurilemma ( no cytoplasm or organelles)

myelin sheath in CNS

when the membrane potential inside the cell increases (becomes more positive). Positive ions enter the cell

depolarization

a return to resting potential is called

repolarization

when the membrane potential inside the cell decreases (becomes more negative). When positive K+ leave the cell or negative Cl- ions enter the cell.

hyperpolarization

depolarization of the cell is called

excitatory

hyperpolarization is called

inhibitory

ICF

intracellular fluid

ECF

extracellular fluid

the process of cellular respiration that takes place in the presence of oxygen gas to produce energy from food

aerobic respiration

the type of respiration through which cells can break down sugars to generate energy in the absence of oxygen

anaerobic respiration

Also called slow oxidative; slower contraction speed; sustain contraction for long periods without fatigue; rich capillary supply; more mitochondria; more myoglobin

slow twitch

faster contraction speed; fatigue fast; thick and fewer capillaries; fewer mitochondria and less myoglobin. Can metabolize anaerobically and found in stronger muscles

fast twitch

a protein found in striated muscles and supplies oxygen to the cells

myoglobin

ADP is combined with P from this using this

Phosphocreatine

- modified endoplasmic reticulum that stores calcium when muscle is at rest - when a muscle fiber is stimulated, calcium diffuses out of the calcium release channels - at the end of a contraction, calcium is actively pumped back in this

sarcoplasmic reticulum

Explain sliding filament theory

- produced by several cross bridges that form between myosin and actin - myosin head serves as myosin ATPase enzyme, splitting ATP into ADP+P. Allows the head to bind to actin when the muscle is stimulated. - release of P cocks the myosin head, producing a power stroke that pulls the thin filament toward the center - After power stroke, ADP is released and a new ATP binds - myosin head straightens out and rebinds - 2 ATP are needed for each stroke

general structure of neurons include:

a cell body, dendrite, and an axon

contains the nucleus, Nissl bodies, and other organelles; cluster in groups called nuclei in the CNS and ganglia in the PNS

cell body

receive impulses and conducts a graded impulse toward the cell body

dendrites

conducts action potentials away from the cell body

axon

the functional connection between a neuron and the cell it is signaling

synapses

if one neuron is signaling another neuron, the first is called the

presynaptic neuron

supportive cell that forms the myelin sheath around peripheral axons in the PNS

Schwann cells

support cell bodies within the ganglia of the PNS

satellite cells

form myelin sheath around the axons of CNS neurons

oligodendrocytes

migrate around CNS tissue and phagocytize foreign and degenerated material

microglia

most abundant glial cell. Have extensions (perivascular feet) that contact blood capillaries and stimulate them to form a seal called the blood-brain barrier

astrocytes

line the ventricles central canal of the spinal cord and secrete cerebrospinal fluid in the CNS

ependymal cells

positively charged ion

cation

negatively charged ion

anion

period after an action potential when the neuron cannot become excited again

refractory period

occurs during the action potential. Na+ channels are inactive

absolute refractory period

when K+ channels are still open. Only a very strong stimulus can overcome this.

relative refractory period

Process of saltatory conduction

- myelin provides insulation, improving the speed of cable properties - Nodes of Ranvier allow Na+ and K+ to cross the membrane every 1 to 2 mm - Na+ ion channels are concentrated at the nodes - action potentials leap from node to node

Physiology Exam Review #1 Flashcards

(68 cards)