Homeostasis 2 (Hamzah) Flashcards Preview

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Flashcards in Homeostasis 2 (Hamzah) Deck (19)
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1
Q

2 key components to reflex pathways

A

response loop and feedback loop

2
Q

reflex pathway: response loop? feedback loop? (describe what happens)

A

starts with stimulus, ends in response of target tissue: sensor monitors environment, afferent signal to integrator when alerted by a change, integrator evaluates signal wrt set point, issues efferent signal, and response feeds back to the input

3
Q

limiting factor of homeostatic control mechanisms is? result?

A

lag time before response and feedback = produce oscillations around the set point

4
Q

positive feedback loops are not ___? what do they do?

A

not homeostatic: reinforce a stimulus and so the regulated variable is sent farther and farther away from the setpoint

5
Q

cannon’s fundamental principles of homeostasis

A

NS aids in preserving fitness of internal environment. some body systems are under tonic control. some body systems under antagonist control. one chemical signal can have different effects in different tissues

6
Q

fitness: def? NS aids in preserving what things?

A

conditions compatible with normal function: blood volume, osmolarity, blood pressure, body temperature

7
Q

tonic control is an example of what type of control?

A

proportional aka tiny constant adjustments

8
Q

examples of antagonistic control

A

insulin and glucagon. sympathetic and parasympathetic neural control

9
Q

approximate volumes of fluid intake

A

intake: 2100 mL/day ingestion, 200 mL/day synthesis

10
Q

approximate volumes of fluid output

A

resp tract, skin diffusion 700 mL/d. sweat very variable. feces 100 mL/d. water also lost from kidneys (excretion)

11
Q

primary means of regulating fluid output?

A

renal excretion: anywhere from 0.5L to 20L per day

12
Q

total body water is how much? distribution of fluid?

A

total body water is 60% body weight. 2/3 intracellular, 1/3 extracellular. most of extracellular is interstitial. 1/4 is plasma. a little bit of transcellular fluid.

13
Q

total body fluid variation?

A

varies with age, sex, obesity. more fat = less water

14
Q

intracellular fluid: % body weight? what comprises it?

A

28L or 40% body weight. cell fluid an individual mix of constituents

15
Q

extracellular fluid: what? % bwt?

A

all fluid outside cells = plasma, etc. 20% bwt ~14L

16
Q

extracellular fluid: continuous exchange with? via?

A

continuous substance exchange with interstitial fluid. via capillary membrane poors

17
Q

what determines fluid distribution between compartments

A

balance of hydrostatic (pressure of a fluid) and osmotic pressures (from dissolved solutes like proteins)

18
Q

most of total osmolarity of body fluids due to? ICF?

A

80% total due to Na and Cl. intracellular fluid osmolarity due to K

19
Q

edema: what? source?

A

excess tissue fluid: mainly ECF, but can also involve ICF