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PHYSIOLOGY > Lecture 1 & 2: Homeostasis and Cell Membrane and Membrane Transport > Flashcards

Lecture 1 & 2: Homeostasis and Cell Membrane and Membrane Transport Flashcards

1
Q

The ability to maintain a relatively stable internal environment in a changing external environment

A

homeostasis

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2
Q

What are 3 examples of situations during which setpoints are shifted?

A

Topor/hibernation
Fever
Puberty

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2
Q

____ is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate

A

Torpor

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3
Q

in order to maintain homeostasis, the body systems must be able to do what 3 things?

A

DETECT deviations in the internal environment
INTEGRATE this info
Make adjustments in order to RESTORE the factor to its desired level

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4
Q

what is the primary type of homeostatic control?

A

negative feedback

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5
Q

How does negative feedback work

A

by defining set points and opposing change

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6
Q

type of homeostatic control that drives physiological values ‘further’ away from the setpoint, amplifying the initial change

A

Positive feedback

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7
Q

this type of homeostatic mechanism tends to destabilize the system in order to facilitate a specific action

A

positive feedback

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8
Q

explain how parturition is an example of positive feedback.

A

uterine contraction increases as fetus O2 demands increase, this causes the fetus to push against the cervix more, causing neuroendocrine reflexes to stimulate the release of oxytocin. Oxytocin release causes more uterine contractions

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9
Q

explain how the stress axis is regulated by negative feedback

A

Cortisol self-regulates by acting on the hypothalamus and anterior pituitary, inhibiting the production of CRH and ACTH which lead to the production of cortisol

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10
Q

explain how primary hypoadrenocorticism (ADDISON’S) is an example of a negative feedback loop

A

A destruction of the function of the adrenal cortex means cortisol production stops, without cortisol, the production of CRH and ACTH is increased

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11
Q

positive feedback ______ the original stimulus

A

INCREASES

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12
Q

explain how ovulation is an example of positive feedback

A
  • estrogen stimulates the release of GnRH from the hypothalamus
    -GnRH stimulates the release of FSH and LH from the anterior pituitary
  • FSH & LH stimulate the release of estrogen from ovaries
  • more estrogen causes the GnRH and LH levels to increase
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13
Q

explain how parturition (Ferguson reflex) is an example of positive feedback

A
  1. uterine contractions occur
  2. baby’s head pushes/stretches cervix
  3. cervix being pushed on leads to oxytocin release
  4. oxytocin release stimulates more uterine contractions
  5. cycle repeats itself
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14
Q

main function of the cellular membrane?

A

separates the inside and outside of the cell

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15
Q

explain the fluid mosaic model

A

the biomembrane is composed of a lipid bilayer embedded with proteins

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16
Q

How is it that the ICF/ECF have a difference in individual ion/molecule composition yet the same osmolarity

A

selective permeability

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17
Q

what two properties influence the ability of a particle to permeate a cell W/OUT assistance?

A
  1. relative solubility of particle in lipid
  2. size of particle
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18
Q

what are the two types of forces involved in the transport of particles across membranes?

A
  1. passive forces (no E)
  2. active forces (E/ATP needed)
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19
Q

4 types of PASSIVE transport?

A

Diffusion (movement of solutes across lipid bilayer)
Osmosis (diffusion of water across membrane)
Channel mediated (diffusion via protein/ion channel)
Facilitated diffusion (carrier-mediated diffusion)

20
Q

2 types of ACTIVE transport?

A

Primary (E required is derived from the direct breakdown of ATP)
Secondary (E required is derived from concentration gradient)

21
Q

passive transport is concentration _________ dependent

A

passive transport is CONCENTRATION GRADIENT DEPENDENT

22
Q

Diffusion depends on the _____ movement of particles

A

Random

23
Q

What factors (5) affect diffusion rate?

A

Fick’s Law of Diffusion
1. Concentration gradient of substance
2. surface area of the membrane
3. Lipid solubility
4. Molecular weight of substance
5. Distance (thickness) of membrane

24
Q

What factors DECREASE diffusion rate

A

weight of substance, distance (thickness) of membrane

25
Q

What factors INCREASE the diffusion rate

A

Concentration gradient, surface area of the membrane, and Lipid solubility

26
Q

What 2 properties of particles influence their ability to permeate the membrane w/out assistance?

A

relative solubility of particle in lipid
size of particle

27
Q

This type of molecular transport opens in response to a stimulus that is specific to that ion and can allow many ions to pass through at once

A

Channel mediated trasnport / gated ion channel

28
Q

what type of transport is the NaK ATPase pump

A

primary active transport - works against concentration gradient, directly utilizes the hydrolysis of ATP to undergo conformational change

29
Q

what type of transport is the sodium glucose transporter (SGLT1)

A

SGLT1 is secondary active transport, ATP is NOT directly used, rather, it is provided by the Na+ gradient

30
Q

carrier mediated transport can/will ______ out whereas simple diffusion does not

A

carrier-mediated transporters (like SGLT1) can/will MAX out b/c the available proteins needed are limited

31
Q

the net diffusion or movement of water down its concentration gradient is ______

A

osmosis

32
Q

the driving force for the movement of water is ?

A

concentration gradient

33
Q

‘permeable membranes’ are permeable to both _____ & _______

A

water and solute

34
Q

semi permeable membranes are permeable to _____ but impermeable to the ________

A

water but impermeable to the solute

35
Q

_________ refers to the total concentration of particles per amount of solution

A

Osmolarity/osmolality

36
Q

what happens if there is a higher concentration of an impermeable substance inside a cell?

A

water has to move and cell volume/shape change

37
Q

_______ refers to the ultimate effect a solution has on cell volume, this determines whether a cell size remains the same, swells or shrinks when solution surrounds the cell

A

Tonicity

38
Q

_______ osmolarity refers to the osmolarity of non-permeable particles in solution, it controls the actual movement of water

A

Effective osmolarity

39
Q

Isotonic conditions

A

no net movement of water, no change in cell volume

40
Q

Hypotonic conditions

A

water diffuses into cell, cell swells

41
Q

Hypertonic conditions

A

water leaves cell, cell shrinks

42
Q

5 clinical signs of hydration status

A
  1. skin turgor (elasticity after tenting skin)
  2. mucous membranes (should be pink and moist)
  3. capillary refill time
  4. eyes (sunken signals dehydration)
  5. hematocrit
43
Q

fraction of plasma occupied by RBCs after centrifugation

A

hematocrit

44
Q

Plasma, interstitial fluid & intracellular fluid have the same osmolarity at _____?

A

equilibrium

45
Q

Any loss or gain of water and or electrolytes must INITIALLY occur in the _____ ?

A

Extracellular fluid (ECF)

46
Q

Electrolytes (like Na+) do not cross the cell membranes and are confined to the ____ ?

A

ECF

47
Q

events that can cause volume contraction

A

diarrhea, water deprivation, adrenal insufficiency

48
Q

events that can cause volume expansion

A

infusion of isotonic NaCl, high water intake, SIADH (Syndrome of inappropriate anti-diuretic hormone secretion)

PHYSIOLOGY (25 decks)

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