Medical Physiology Test #1

Front 1

The basic living unit

Back 1

cell

Front 2

Referred to as "internal environment" is called _____

Back 2

Extracellular Fluid

Front 3

T or F: Most of the fluid in the body is extracellular

Back 3

False. Extracellular accounts for only 1/3 of the fluid.

Front 4

_____fluid contains large amounts of sodium, chloride, and bicarbonate ions plus nutrients such as oxygen, glucose, fatty acids and amino acids

Back 4

Extracellular

*It also contains carbon dioxide that is being transported form the cells to the lungs to be excreted, plus other cellular waste products that are being transported to the kidneys for excretion.

Front 5

____ fluid contains large amounts of potassium, magnesium, and phosphate ions

Back 5

Intracellular

Front 6

Means maintenance of nearly constant conditions in the internal environment

Back 6

Homeostasis

Front 7

The process of diffusion is caused by ____ motion of the molecules in both the plasma and the interstitial fluid.

Back 7

kinetic

Front 8

The most abundant of all ends products of metabolism is ____.

Back 8

Carbon dioxide

Front 9

How do kidneys perform their function of filtering waste?

Back 9

They first filter large amounts of plasma through the glomeruli into the tubules and then reabsorb into the blood those substances needed by the body such as glucose, amino acids, appropriate amounts of water, and many of the ions. Most of the other substances that are not needed by the body (such as urea), are NOT reabsorbed and pass through the renal tubules into the urine.

Front 10

The 3 major parts of the nervous system are:

Back 10

1. sensory input
2. central nervous system (integrative)
3. motor output

Front 11

These are a system of regulation that complements the nervous system.

Back 11

Hormones

*Endocrine glands (8 major in body) secrete hormones.

Front 12

Briefly describe regulation of oxygen and CO2 concentrations in the extracellular fluid

Back 12

Oxygen-buffering function of hemoglobin (hemoglobin has own affinity for oxygen, will release only if oxygen concentration in blood is low).
High CO2 levels excite respiratory center - breath faster and blow off CO2

Front 13

Describe regulation of arterial blood pressure

Back 13

Baroreceptor stimulated by stretch send nerve impulses to medulla of brain inhibiting vasomotor center which decreases number of impulses from the vasomotor center through the sympathetic nervous system to diminish pumping activity and dilate peripheral blood vessels.

If baroreceptors not stretched, vasomotor center is more active causing vasoconstriction and increased heart pumping - increasing BP

Front 14

T or F: Most control systems of the body act by positive feedback.

Back 14

FALSE. Most control systems act by NEGATIVE feedback.

Front 15

Name an instance where positive feedback is useful.

Back 15

1. Blood clotting. Clotting factors activate more clotting factors - increasing clotting.
2. Childbirth (uterine contractions). Uterine contractions become stronger with stretch of cervix
3. Nerve Signals (sodium leaking causing more and more sodium channels to open - increasing nerve action potential)

Front 16

What are the 2 basic processes for transport through a cell membrane?

Back 16

1. Diffusion
2. Active Transport

Front 17

What are the 2 types of diffusion?

Back 17

1. Simple
2. Facilitated

Front 18

_____ diffusion is kinetic movement of molecules or ions through a membrane without interaction with a carrier protein. _____ diffusion requires interaction of a carrier protein.

Back 18

1. Simple
2. Facilitated

Front 19

Rate of diffusion is determined by:

Back 19

1. amount of substance available
2. velocity of kinetic motion
3. # and sizes of openings in the membrane

Front 20

T or F: Diffusion through a lipid bilayer will increase if the substance is lipid soluble.

Back 20

True.

*oxygen, nitrogen, CO2, and alcohols are lipid soluble - diffuse easily.
*The rate of diffusion:lipid solubility of substance

Front 21

Water is insoluble. Why then does it diffuse very rapidly through the cell membrane?

Back 21

It passes through protein channels in the membrane with "watery channels". Other lipid insoluble molecules can also pass this way, but the bigger the slower.

Front 22

Protein channels have 2 important characteristics - what are they?

Back 22

1. selectively permeable to certain substances
2. opened/closed by gates

Front 23

Name and describe the 2 types of gating of protein channels

Back 23

1. Voltage gating: molecular conformation of the gate or of its chemical bonds responding to the electrical potential across the cell membrane. For ex: Negative charge inside cell keeps gate closed tightly to Na+, but as charge becomes more positive, Na+ gate opens allowing Na+ to flow inward.
2. Chemical (ligand) gating: gate opens when a chemical substance (ligand) bonds to the protein causing a conformational change. Example: ACh binds allowing the negatively charged pore to allow uncharged & positive ions (smaller than diameter) to influx.

Front 24

T or F: A channel either opens completely or not at all.

Back 24

True. "all or none"

Front 25

T or F: The rate of facilitated diffusion:concentration of diffusing substance.

Back 25

False. In facilitated diffusion, the rate increases proportionally but then approaches a max (Vmax) because the rate at which molecules can be transported can never be greater than the rate that the protein carrier can undergo change back and forth (conformational change).

*Simple diffusion does NOT reach a max

Front 26

This type of diffusion requires a carrier protein. What are some substances transported this way?

Back 26

Facilitated Diffusion; glucose, amino acids

Front 27

T or F: The rate of net diffusion into a cell is proportional to the concentration on the outside minus the concentration on the inside.

Back 27

True.

Net Diffusion is approximately Co - Ci

Front 28

What is the Nernst Potential/Equation?

Back 28

Defined: The diffusion potential level across a membrane that exactly opposes the net diffusion of a particular ion through the membrane.


EMF (electromotive force) =
(+/-) 61 x log C(inside) / C(outside)

Example: if charge is placed on the inside and outside of a membrane (electrical gradient), a NEG ion will move from the NEG side of the membrane to the POS side of the membrane until the concentration differences rises high enough that the two effects balance each other out. At normal body temperature, the electrical difference that will balance a given concentration difference of univalent ions is determined by the Nernst equation.

The Nernst potential is the potential inside the membrane. The sign of the potential is (+) if the ion diffusing from the inside to outside is a negative ion and is (-) if the ion is positive

Front 29

The process of net movement of water caused by a concentration difference is called:

Back 29

Osmosis

Front 30

Osmotic pressure is:

Back 30

The exact amount of pressure required to stop osmosis

Front 31

T or F. Osmotic pressure is determined by the mass of particles per unit volume of fluid.

Back 31

False. Osmotic pressure is determined by the NUMBER of particles per unit of volume of fluid. For example: glucose < Cl2 since chloride with dissociate in fluid = 2 molecules where glucose will not. Molar concentration of glucose = 1
Molar concentration of Cl2 = 2

Front 32

The number of osmoles per liter of solution is called

Back 32

osmolarity

*osmolarity is basically equivalent to osmolality (osmoles/kg of water)

Front 33

The process for moving ions against concentration gradient is called ____ transport.

Back 33

Active

Front 34

T or F: Primary and Secondary active transport both require carrier proteins.

Back 34

True

Front 35

Sodium-Potassium pump is a ____ active transport system that moves _ molecules of sodium ____ the cell and _ molecules of potassium ____ the cell.

Back 35

primary; 3; outside; 2; inside

*After 3 sodium ions bind to the portion of the protein protruding to the inside of the cell and 2 potassium ions bind to the protein protruding to the outside then ATP cleaves one phosphate to become ADP which causes the conformation change of the protein taking 3 sodium ions to the outside and 2 potassium ions to the inside

Front 36

The difference between Primary and Secondary active transport is:

Back 36

Primary uses ATP; Secondary uses energy stored in the form of ionic concentration differences.

Front 37

T or F: The Sodium/Potassium pump regulate cell volume

Back 37

True.

Front 38

This pumps system is said to be electrogenic because it creates an electrical potential across the cell membrane.

Back 38

Na+/K+ pump.

It pumps 3 Na+ outside and 2 K+ outside leaving the inside "negative" an creating an electrical potential across the cell membrane.

Front 39

The calcium pump is a ___ active transporter of calcium ions. Calcium levels are __ in the cytosol.

Back 39

primary (uses ATP); low

*There are 2 calcium pumps - one pumps calcium to the outside of the cell and the other into other organelles such as the ER or sarcoplasmic reticulum.

Front 40

Hydrogen Ions are transported by ____ active transport. Important in the ___ and ____,

Back 40

primary; stomach and kidneys

Front 41

Co-transport is an example of ____ active transport.

Back 41

Secondary

Front 42

Glucose and amino acids are transported into cell against large concentration gradients through ___ transport which is a _____ active transport.

Back 42

Co-transport; secondary

*after BOTH sodium and glucose attach to the transport protein, a conformation changes occurs transporting the substances.

Front 43

Active transport through cellular sheets occur in:

Back 43

1. intestinal epithelium
2. epithelium of the renal tubules
3. epithelium of all exocrine glands
4. epithelium of the gallbladder
5. membrane of the chorioid plexus of the brane and other membranes

Front 44

Transport for a substance through a cellular sheet involves ___ transport through the cell membrane on one side and ___ or ____ on the opposite side of the cell.

Back 44

active; simple diffusion or facilitated diffusion

Front 45

Calculation of the Diffusion potential when the membrane is permeable to several different ions

Back 45

Goldman equation

Front 46

Rapid changes in __ and __ permeability are primarily responsible for signal transmission in nerves.

Back 46

Na and K

Front 47

The resting membrane potential of large fibers when not transmitting nerve signals is about ___ millivolts.

Back 47

-90 mV

*this means that the potential inside the fiber is 90 mV more negative than the potential in the extracellular fluid on the outside of the fiber

Front 48

In the K+/Na+ "leak" channel, the channel is far more permeable to ___ than to ___.

Back 48

potassium; sodium

*potassium is approximately 100 times as permeable as sodium.

Front 49

Normal Resting Potential Membrane of K+ alone= -94. Na+= +61 while Na+/K+= -86 mV and Na+/K+ plus diffusion= -90 mV. Why doesn't Na+ change the difference significantly and why more negative when taking diffusion into account?

Back 49

The difference is due to K+ being more permeable to the membrane than Na+. Goldman equation gives -86 when calculated because it permeability into account. The extra -4 mV from -86 to -90 is due to more sodium ions being pumped to the outside than potassium inside.

Front 50

Rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane are called:

Back 50

Action potentials

Front 51

The membrane is said to be ____ during the resting stage before the action potential begins.

Back 51

Polarized

Front 52

Depolarization is caused by the flow of ___ ions ___ the cell.

Back 52

Sodium; inside

The potential rising rapidly in the positive direction is called depolarization.

Front 53

Re-polarization is the rapid diffusion of ___ ions to the ___ of a cell causing a ____ resting membrane potential.

Back 53

potassium; outside; negative

Front 54

When the membrane potential becomes ____ negative, it causes a sudden conformational change in the activation gate of sodium flipping it all the way open - this is called the ____ state where sodium ions can pour inward through the channel.

Back 54

less; activated

*Resting state rises from -90 to somewhere between -70 and -50.

Front 55

T or F: The same increase in voltage that opens the Na+ activation gate also closes the Na+ gate.

Back 55

True.

The inactivation gate is just slightly slower at closing as the activation gate is at opening.

Front 56

T or F: Voltage gated K+ channels open due to an increase in membrane potential.

Back 56

True.

When the membrane potential rises from -90 mV towards zero, the change causes a conformational opening of the potassium gate and potassium diffuses outward. Due to the slight delay in opening, they open just at the same time that the sodium channels are beginning to close.

Front 57

___ ion can serve along with or sometimes instead of sodium in some cells to cause an action potential.

Back 57

Calcium

Front 58

T of F: Voltage-gated calcium channels are slightly permeable to sodium ions as well as calcium and are therefore called Ca++/Na+ channels.

Back 58

True.

These channels are slow to become activated and are called slow channels; in contrast sodium channels are called fast channels.

Front 59

Calcium channels are numerous in ____ muscle and ____ muscle.

Back 59

Cardiac; smooth

Front 60

Nerve fibers are highly excitable when there is a ____ of calcium ions.

Back 60

Deficit.

Sodium channels become activated by very little increase in membrane potential. Only 50% decrease in Ca++ below normal and spontaneous discharge can occur = tetany.

Front 61

Opening of Sodium channels is a ____-feedback cycle.

Back 61

Positive.

Front 62

Threshold for initiation of the action potential is __ mV.

Back 62

-65mV

An action potential will not occur until the initial rise in membrane potential is great enough to create the vicious cycle of opening sodium gates.

Front 63

The depolarization process that travels the entire length of the fiber (forward/backward) is called a ___.

Back 63

Nerve or muscle impulse

Front 64

Sodium ions diffuse ____ during depolarization and potassium ions diffuse ____ during re-polarization.

Back 64

inside; outside

Front 65

What is a plateau in an action potential? Where does this occur?What is it due to?

Back 65

A plateau means that the excited membrane does not re-polarize immediately after depolarization but the potential remains at at peak for 0.2-.03 seconds.
This occurs in heart muscle fibers and causes contraction of heart muscle to last for this same long period.
A plateau in some action potentials is due to the types of channels (fast and slow) responsible for depolarization and that potassium channels are slower than usual to open.

Front 66

The membrane that conducts the action potential is called the ____.
It has a protective covering called the ______. The areas that are not covered are called ______ and are where action potentials occur.

Back 66

axon; myelin sheath; nodes of Ranvier

Front 67

Saltatory conduction means:

Back 67

the nerve impulse jumping down the fiber from one node to another node

Front 68

T or F: A weak stimulus causes a local potential change at the membrane even if there is not an action potential.

Back 68

True.

When acute local potentials fail to elicit an action potential they are called acute sub-threshold potentials. The local potential must rise to the threshold before an action potential is set off.

Front 69

The period during which a second action potential cannot be elicited is called:

Back 69

absolute refractory period

Front 70

Factors that decrease excitability are called ____. Examples are:

Back 70

stabilizers. Local anesthetics.

*high extracellular calcium ions decreases membrane permeability of sodium and simultaneously reduces excitability and therefore, calcium ions are said to be a stabilizer.

Front 71

The channeling and processing of information is called _____.

Back 71

integrative function

>99% of all sensory information is discarded by the brain as irrelevant and unimportant.

Front 72

The junction point between one neuron and the next is called the _____.

Back 72

synapse

*synapses perform a selective action - often blocking weak signals and allowing strong signals to pass. At other times it amplifies weak signals. (Facilitatory and Inhibitory signals)

Front 73

The 3 major levels of the central nervous system are:

Back 73

1. spinal cord level
2. lower brain or subcortical level
3. higher brain or cortical area

Front 74

Neuronal circuits in the ____ level cause walking movements, reflexes that withdraw portions of the body from painful objects, reflexes that stiffen the legs to support the body against gravity and reflexes that control local blood vessels, GI movements, urinary excretion.

Back 74

spinal cord

Front 75

Subconscious activities of the body are controlled in the _____ level of the brain. This includes the medulla, pons, mesencephalon, hypothalamus, thalamus, cerebellum, and basal ganglia.

Back 75

lower brain or subcortical level

*subconscious activities include arterial pressure, respiration, control of equilibrium, salivation.
*Many emotional patterns such as anger, excitement, sexual response, reaction to pain/pleasure, can still occur after destruction of much of the cerebral cortex

Front 76

_____ is an extremely large "memory storage warehouse". It is essential for thought process.

Back 76

Higher Brain or Cortical Level.

*The cerebral cortex never functions alone but always in association with the lower centers of the nervous system.

Front 77

Name the 2 types of synapses and what you know about them!

Back 77

1. Chemical - neurotransmitters (one-way conduction) released by presynaptic neuron to postsynaptic neuron.
2. Electrical - gap junctions that allow free movement of ions from the interior of one cell to the interior of the next. (smooth muscle and cardiac muscle; signals can transmit in either direction)

Front 78

The presynaptic terminal contains 2 important internal structures. What are they and what do they do?

Back 78

1. Transmitter vesicles: contain transmitter substance that either excites or inhibits the postsynaptic neuron.
2. Mitochondria: provides ATP that supplies energy for synthesizing new transmitter substance

Front 79

The presynaptic membrane contains voltage-gated _____ channels. The quantity of transmitter substance that is release from the terminal into the synaptic cleft is (choose: directly/indirectly) related to the number of ions that enter.

Back 79

calcium; directly

Front 80

A transmitter that opens cation channels in the postsynaptic membrane is called an ______ transmitter. A transmitter that opens anion channels are called _____ transmitters.

Back 80

excitatory; inhibitory.

Cation channels are lined with negative charges and attract positively charged sodium ions into the channel - negative ions are repelled.
Anion channels allow chloride ions to pass into the channels.

When a transmitter activates an ion channel, it opens for a fraction of a millisecond and closes when the neurotransmitter is no longer present - equally as fast.

Front 81

Prolonged postsynaptic neuronal excitation or inhibition is achieved by ______.

Back 81

Activating a "second messenger"

*A G-protein is the most common type second messengers

Front 82

Name the 4 changes that can occur on activation of a G-protein.

Back 82

1. opening of specific ion channels (allows channel to stay open for prolonged period of time).
2. activation of cAMP or cGMP (can cause long-term changes in cell structure itself which alters long-term excitability of the neuron).
3. Activation of intracellular enzymes (can cause one of many specific chemical functions in the cell)
4. Activation of gene transcription (causes formation of new proteins within the neuron which changes its metabolic machinery or its structure).

Front 83

Distinguish between excitation or inhibition.

1. Opening of chloride ion channels through the postsynaptic neuronal membrane
2. Opening of sodium channels to flow to the interior of the postsynaptic cell.
3. Depressed conduction through chloride or potassium channels, or both.

Back 83

1. Inhibition
2. Excitation
3. Excitation

Front 84

Small-molecule, rapidly acting and neuropeptides are the two groups of what? What is the difference?

Back 84

neurotransmitters

Small-molecule, rapid acting transmitters cause acute responses in the nervous system - they act rapid. Synthesized in the cytosol of the presynaptic terminal . They either increase sodium conductance (excitation) or increase potassium or chloride conductance (inhibition). Vesicles are reused. Acetylcholine is a typical small-molecule transmitter.
Neuropeptides are synthesized in ribosomes - very laborious, but they are generally a thousand times more potent than small-molecule transmitters and cause prolonged actions. Vesicle is autolyzed/not reused.

Front 85

What neurotransmitter always causes excitation?

Back 85

Glutamate.

Front 86

This small-molecule, fast acting transmitter helps control overall activity and mood of the mind. Mostly excitatory, but some inhibition.

Back 86

Norepinephrine

Front 87

This small-molecule, fast acting neurotransmitter is secreted in many areas of the nervous system. It is mostly excitatory, but can have inhibitory effects such as inhibition of the heart by the vagus nerves.

Back 87

Acetylcholine

Front 88

This small-molecule, fast acting neurotransmitter is secreted by nerve terminals in the brain responsible for long-term behavior and memory. It is NOT formed or stored in the vesicles in the presynaptic terminal but synthesized instantly out of need and then diffuses of of the presynaptic terminal into the postsynaptic terminal where it changes intracellular metabolic functions that modify neuronal excitability of seconds, minutes, or even longer

Back 88

Nitric Oxide

Front 89

Resting membrane potential for a spinal motor neuron is ____ mV.

Back 89

-65 mV

*remember that peripheral nerve and skeletal nerve fiber resting membrane potential is -90mV.

Front 90

A potential that exactly opposes movement of an ion is called the _____ for that ion.

Back 90

Nernst potential

Front 91

The positive increase (less negative) in voltage above the normal resting neuronal potential is called the _____.

Back 91

Excitatory postsynaptic potential (EPSP).

Front 92

The threshold for excitation of a neuron is ____ mV.

Back 92

-45 mV.

*this means that EPSP is +20mV

Front 93

Inhibitory synapses open mainly ___ channels.

Back 93

Chloride

*If Chloride channels are opened, the chloride ions move in the cell and make the membrane potential more negative (-70mV); this is called HYPER-POLARIZATION

Front 94

An increase in negativity beyond normal resting membrane potential level is called ______.

Back 94

Inhibitory postsynaptic potential (hyper-polarization)

Front 95

Inhibition that occurs at the presynaptic terminal before the signal ever reaches the synapse is called _____. In most instances, the inhibitory transmitter is _____.

Back 95

Presynaptic inhibition; GABA (opens anion channels into terminal fibril; the negative charges of these ions cancel out the excitatory effect of the positive sodium ions).

Front 96

T or F: A single presynaptic terminal can excite a neuron.

Back 96

False.

*EPSP by a single terminal will be no more than 0.5-1 mV. Remember that the threshold is -45 or an EPSP of +20, so many presynaptic terminals must be stimulated at the same time. Their effects add to one another or SUMMATE.

Front 97

What is the difference between spatial and temporal summation?

Back 97

Spatial is the effect of summing simultaneous postsynaptic potentials by multiple terminals of a widely spaced area of the neuronal membrane.
Temporal is successive discharges from a single presynaptic terminal. If they are rapid enough, they can add to one another or summate.

Front 98

When a membrane potential is near the threshold for firing, but not yet at he firing level, the neuron is said to be ____.

Back 98

facilitated

*Another excitatory signal entering the neuron from another source can easily excite the neuron that is facilitated.

Front 99

80-95% of all presynaptic terminals of the anterior motor neuron terminate on ____, in contrast to only 5-20% terminating on the ____.

Back 99

dendrites; soma

Front 100

Synapses that lie near the soma have a greater effect in causing neuron excitation or inhibition than those that lie far away from the soma due to ______.

Back 100

Decremental conduction

*Dendrites are long with thin membranes making them "leaky" to electric current. Before the potential can reach the soma, some of the potential is lost by this leakage. The decrease in membrane potential is called decremental conduction; hence, the further away from the soma the less effect and vice versa.

Front 101

T or F: Different neurons respond differently, have different threshold for excitation, and different maximum frequencies of discharge.

Back 101

True.

Front 102

___ is a protective mechanism against excessive neuronal activity. Give an example when it is protective.

Back 102

Fatigue; example= seizure eventually stops

*Fatigue is exhaustion or partial exhaustion of the stores of transmitter substances in the presynaptic terminals.

Front 103

Alkalosis ____ neuronal excitability.
Acidosis ____ neuronal excitability.
Cessation of oxygen _____ neuronal excitability.

Back 103

increases; decreases; decreases and can even stop

Front 104

Drugs that can reduce the threshold for excitation of neurons include:

____ is a drug that inhibits the action of some normally inhibitory transmitter substances (increasing excitability) - resulting in severe tonic muscle spams.

Back 104

caffeine (coffee), theophylline (tea), theobromine (cocoa)

Strychnine

Front 105

Most anesthetics ______ the neuronal membrane threshold for excitation and thereby _____ synaptic transmission at many points in the nervous system.

Back 105

increase; decrease

Front 106

Drinking a liter of distilled water will:
__ ECF volume __ ECF osmolarity ___ ICF volume ___ ICF osmolarity

Back 106

increase; decrease; increase; decrease

Drinking water hydrates both intracellular and extracellular volume. Likewise it decreases their osmolarity.

Front 107

Drinking one liter of isotonic saline will:
___ ECF volume ___ ECF osmolarity
___ ICF volume ___ ICF osmolarity

Back 107

increase; no change; no change; no change

Front 108

Drinking one liter of sea salt will:
___ ECF volume ___ ECF osmolarity
___ ICF volume ___ ICF osmolarity

Back 108

increase; increase; decrease; increase

Front 109

Eating salty potato chips will:
___ ECF volume ___ ECF osmolarity
___ ICF volume ___ ICF osmolarity

Back 109

increase; increase; decrease; increase

Front 110

Not eating or drinking for 24 hours will:
___ ECF volume ___ ECF osmolarity
___ ICF volume ___ ICF osmolarity

Back 110

decrease; increased; decreased; increased

Dehydrates both intracellular and extracellular, no change to osmolarity