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Human Physiology > Unit 1 > Flashcards

Unit 1 Flashcards

1
Q

Define Homeostasis

A

the tendency of a living body to maintain relatively stable conditions

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2
Q

negative feedback loop

A

a mechanism that keeps a variable close to set point; the body senses a change and reverses it

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3
Q

receptor

A

a structure that detects a change in the body

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4
Q

integrating center

A

what processes the information and makes a decision and directs the response (typically the brain)

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5
Q

effector

A

a cell or organ that carries out the final corrective action

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6
Q

what is an example of a negative feedback loop?

A

a thermostat

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7
Q

positive feedback loop

A

a mechanism that detects a change and increases the change rather than bringing it pack to set point

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8
Q

function of lipids

A

contribute to membrane tension, rigidity, and overall shape

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8
Q

structure of the plasma membrane

A

the boundaries of a cell that is made of lipids and proteins

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9
Q

function of proteins

A

bind chemical signals to trigger internal changes and catalyze reactions

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10
Q

saturation

A

as solute concentration rises, rate of transport rises, but only to the transport maximum

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11
Q

glycocalyx and it’s function

A

“fuzzy” outer layer of the cell membrane and functions as the cell “fingerprint.” It protects, gives immunity to infection

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12
Q

Transport material through a cellular membrane

A

plasma membranes and organelle membranes have selectively permeable membranes which allow some, but not all things from passing through

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13
Q

Diffusion

A

the net movement of particles from a place of high concentration to a lower concentration. (passive mechanism, no ATP)

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14
Q

filtration

A

where particles are driven through the membrane by physical pressure. (Passive, no ATP)

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15
Q

osmosis

A

the net flow of water through a selectively permeable membrane. (passive, no ATP)

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16
Q

primary active transport

A

when a carrier moves solute through a membrane up its concentration gradient (Active, uses ATP)

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17
Q

aquaporins

A

special channels for water that increase the rate of osmosis

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18
Q

Secondary Active transport

A

where a carrier moves solute through the membrane but only uses ATP indirectly.

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19
Q

endocytosis

A

brings material into cell

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20
Q

exocytosis

A

releases material from cell

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21
Q

osmolarity

A

osmotic concentration; the quantity of nonpermeating solutes per liter of solution

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22
Q

tonicity

A

the ability of a surrounding solution to affect fluid volume and pressure in a cell

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23
Q

hypertonic solution

A

all water leaves the cell toward the higher concentration of soutes, causing the cell to shrivel/shrink

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24
Q

isotonic solution

A

the cell would remain the same, with no movement of water

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25
Q

hypotonic solution

A

all water would go into the cell toward the higher concentration of solutes, causing the cell to grow

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26
Q

passive transport

A

requires no ATP; things move down the concentration gradient from high to low concentration

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27
Q

active transport

A

requires ATP; things move up the concentration gradient

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28
Q

uniport

A

a carrier that moves one type of solute (ex: calcium pump)

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29
Q

symport

A

a carrier that moves two or more solutes simultaneously in the same direction (ex: sodium-glucose transporters)

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30
Q

antiport

A

a carrier that moves two or more solutes in opposite directions (ex: sodium-potassium pump)

31
Q

Types of endocytosis: phagocytosis

A

engulfing and destroying large particles; “cell-eating”

32
Q

Types of endocytosis: pinocytosis

A

taking droplets of ECF containing molecules useful in the cell; “cell-drinking”

33
Q

Types of endocytosis: Receptor-mediated endocytosis

A

particles bind to specific receptors on the plasma membrane

34
Q

How many types of RNA are there? and list them

A

3: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA)

34
Q

DNA (deoxyribonucleic acid)

A

a long thread-like molecule with a uniform diameter in a double helix shape

35
Q

RNA

A

single nucleotide chain that functions mainly in the cytoplasm of the cell and build proteins

36
Q

5 universal properties of muscle:

A

Excitability, conductivity, contractility, extensibility, elasticity

37
Q

Excitability

A

responsiveness to chemical signals, stretch, and electrical changes across the plasma membrane

38
Q

conductivity

A

local electrical excitation sets off a wave of excitation that travels along the muscle fiber

39
Q

contractility

A

shortens when stimulated

40
Q

extensibility

A

capable of being stretched between contractions

41
Q

elasticity

A

returns to its original rest length after being stretched

42
Q

myofibril

A

long protein cords occupying most of the sarcoplasm

43
Q

thick filaments

A

made of several hundred myosin molecules and responsible for contraction and regulating contraction

44
Q

thin filaments

A

composed of 3 protein types: fibrous actin, tropomyosin, and troponin

45
Q

fibrous actin

A

2 intertwined strands of globular actin subunits, each with an active site that can bind to a head of a myosin molecule

46
Q

tropomyosin

A

each block 6 or 7 active sites on G actin subunits

47
Q

troponin

A

small calcium binding protein on each tropomyosin molecule

48
Q

elastic filament

A

made of huge springy protein called titin. runs through the thin filament. helps stabilize and position the thick filament. prevents overstretching.

49
Q

sarcomere

A

the functional contractile unit of a muscle fiber. Composed of: I bands, A bands, H bands, M line, and z disc

50
Q

I band

A

Light band; include actin (thin filament) only

51
Q

A band

A

dark band where thick and thin filaments overlap; include actin and myosin

52
Q

H band

A

not as dark; middle of A band; includes myosin (thick filament) only

53
Q

M line

A

dark, transverse protein in the middle of the H band

54
Q

Z disc

A

protein complex that provides anchorage for thin and elastic filaments

55
Q

Phases of Muscle Contraction

A
  1. Excitation
  2. Excitation/Contraction Coupling
  3. Contraction
  4. Relaxation
56
Q

Phase 1: Excitation

A
  1. Nerve signal arrives and calcium ions enter the terminal
  2. ACh is released into the synaptic cleft
  3. ACh binds to receptors on the sarcolemma
  4. Ligand-gated channels open and calcium flows into the cell while potassium flows out, creating end plate potential
  5. Action potential is created
57
Q

Phase 2: Excitation/Contraction Coupling

A
  1. Action potential spreads through T tubules
  2. Calcium released from terminal cisterns of SR
  3. Calcium binds to troponin
  4. Tropomyosin moves out of the way for myosin heads to bind to actin
58
Q

Phase 3: Contraction

A
  1. ATP is hydrolyzed into ADP and Pi
  2. The myosin-actin cross-bridge forms
  3. The power stroke slides the thin filament over the thick filament
  4. Binding of new ATP breaks cross-bridge
59
Q

Phase 4: Relaxation

A
  1. Cessation of nervous stimulation and ACh release
  2. ACh breakdown by acetylcholinesterase (AChE)
  3. Reabsorption of calcium ions by SR
  4. Calcium no longer binds to troponin
  5. Tropomyosin moves back to block binding sites
60
Q

Sliding filament theory

A

the mechanism of skeletal muscle contraction where myofilaments do not shorten, but the sarcomere does

61
Q

sarcoplasmic reticulum

A

the smooth endoplasmic reticulum that forms a network around each myofibril

62
Q

length-tension relationship

A

the amount of tension generated by a muscle depends on how stretched or shortened it was before it was stimulated

63
Q

three phases of a muscle twitch

A

latent period
contraction phase
relaxation phase

64
Q

muscle twitch

A

a quick cycle of contraction and relaxation when a muscle is directly stimulated with an electrode

65
Q

latent period

A

delay just after stimulation of a muscle

66
Q

contraction phase

A

external tension is generated and a load is moved as the muscle fiber shortens

67
Q

relaxation phase

A

sarcoplasmic calcium levels fall as calcium is reabsorbed into SR, tension declines

68
Q

temporal (wave) summation

A

where each new twitch piggybacks on the previous one, generating higher tension

69
Q

Recruitment (multiple motor unit summation)

A

the process of bringing more motor units into play with stronger stimuli

70
Q

size principle

A

weak stimuli recruit small units and strong stimuli recruit large units

71
Q

complete tetanus

A

when unnaturally high stimulus frequencies (in lab experiments) cause a steady contraction

72
Q

incomplete tetanus

A

when only partial relaxation between stimuli results in fluttering

73
Q

concentric contraction

A

muscle shortens as it maintains tension (ex: lifting weight)

74
Q

isometric contraction

A

contraction without change in length

75
Q

eccentric contraction

A

muscle lengthens as it maintains tension (ex: slowly lowering weight)

Human Physiology (3 decks)

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