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Psych 230 exam 2 > 5. Homeostasis: Active Regulation of the Internal Environment > Flashcards

5. Homeostasis: Active Regulation of the Internal Environment Flashcards

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1
Q

Homeostasis

A

The active processes that take place in the body to balance internal environment

Sometimes includes behaviors that you do to maintain a normal state

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2
Q

Thermoregulation

A

The active processes of closely regulating body temperature around a set value

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3
Q

Endotherms

A

Generate most of their own heat through internal processes

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4
Q

Pros of endotherms

A
  • independence from environmental conditions
  • improved oxygen use capacity sustains greater muscular activity
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5
Q

Cons of endotherms

A

Uses a lot of food energy to produce heat

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6
Q

Homeostatic mechanisms that regulate temperature, body fluids, and metabolism are primarily ___________ feedback systems

A

negative

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7
Q

Set point

A

most ideal point

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8
Q

Set zone

A

Range of tolerance in a system

You’re okay if you’re in this zone

Allows for flexibility so you’re not turning on regulating systems all the time

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9
Q

Thermoregulation in mammals

A

Receptors detect temperature all around the body: skin, body core, hypothalamus

They receive info → send info to spinal cord, brain stem, and hypothalamus

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10
Q

Thermoregulation in humans

A

The body has multiple physiological systems for the generation of heat; preoptic area of the hypothalamus is an important area

  • Restricting blood vessels to warm you up
  • Dilating blood vessels to cool you down
  • Breaking down brown fat
  • Shivering
  • Increased thyroid activity
  • Sweating
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11
Q

Ectotherms

A

Get most of their heat from the environment

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12
Q

Thermoregulation: endotherms AND ectotherms

A

Behavioral regulation of temperature

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13
Q

3 strategies for behavioral regulation of temperature

A

Change exposure of the body surface
Ex: huddle to cover your limbs when you’re cold

Changing external insulation
Ex: building a nest, putting on layers

Changing surroundings
Ex: going underground, going into a warm room

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14
Q

Behavioral thermoregulation in bacteria-challenged lizards

A

Iguanas will regulate their body temperature using a heat lamp

If exposed to bacteria, it will create a “fever” by moving toward a heat source
–> Behavioral fever

Ectotherms have to manually bring their core temperature up to kill off virus

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15
Q

Fluid regulation

A

We are constantly using and replenishing water and salts (urination, breathing, etc.), so we have both physiological and behavioral mechanisms to replace them

The brain itself is almost 80% water, so a careful balance of fluids and dissolved salts is required so it can function

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16
Q

Water is balanced between two body compartments

A

Intracellular compartment
Extracellular compartment

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17
Q

Intracellular compartment

A

Fluid contained within our cells where most water resides

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18
Q

Extracellular compartment

A

Fluid outside of our cells

Interstitial fluid: fluid in between cells
Blood plasma: protein-rich fluid that carries red and white blood cells

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19
Q

Aquaporins

A

Water moves in and out of cells through aquaporins via osmosis

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20
Q

Osmosis

A

The passive movement of a solvent (the liquid) to move through a membrane in order to equalize the concentration of solute
(molecules of a substance)

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21
Q

Osmotic pressure

A

The physical force that pushes or pulls water across the membrane due to differences in concentrations of salts

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22
Q

Osmolality

A

Number of solute particles per unit volume of solvent

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23
Q

Isotonic salt solution

A

Mixture of salt and water

About 0.9% sodium chloride

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24
Q

A ____ solution has more salt than an isotonic solution, while a ____ solution has less salt

A

Hypertonic, hypotonic

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25
Q

How does salt impact cells?

A

If cells are surrounded by saltier solutions (that is, a hypertonic solution), they will lose water

If they are surrounded by less salty solutions (a hypotonic solution), water will push into the cells

If excessive, this movement can damage or even kill cells

26
Q

Two kinds of thirst

A

Osmotic thirst
Hypovolemic thirst

27
Q

Osmotic thirst

A

If the outside of your cells have more salt, water leaves the cells

This is usually why we feel thirsty: obligatory water loss by normal physiological processes like respiration, perspiration, and urination, or eating a salty meal

28
Q

Hypovolemic thirst

A

Loss of volume of extracellular fluid

29
Q

______ in the hypothalamus respond to changes in osmotic pressure as water is drawn out of cells by osmosis

A

Osmosensory neurons

30
Q

Important brain regions in osmotic thirst

A

areas in the hypothalamus (POA, supraoptic nucleus, anterior hypothalamus) and the circumventricular organs

31
Q

Circumventriuclar organs

A

Lie in the walls of the ventricles

Thinning in the blood-brain barrier at these locations so they can better detect concentration of solute particles

32
Q

Baroreceptors

A

Located in major blood vessels and the heart

Detect drop in blood pressure

33
Q

Remedy to osmotic thirst

A

Water

34
Q

Remedy to hypovolemic thirst

A

Water and salts

35
Q

Hypovolemia causes release of _____, or antidiuretic hormone (ADH)

A

Causes release of vasopressin

From the posterior pituitary gland

Induces blood vessel constriction and reduces water flow to the bladder

36
Q

Renin

A

Kidneys release enzyme called renin to conserve water from hypovolemia

Triggers other hormones, resulting in circulation of angiotensin II

37
Q

Angiotensin II

A

Conserves water by constricting blood vessels, increasing blood pressure, and releasing vasopressin and aldosterone

Angiotensin II also acts at the circumventricular organs to stimulate drinking

38
Q

Glucose

A

Principal sugar used for energy

39
Q

Glycogen

A

Complex carbohydrate made by combining a bunch of glucose molecules and then storing it for a short time in the liver and muscles

40
Q

Glycogensis

A

The process of converting glucose to glycogen, regulated by the pancreatic hormone insulin, released by beta cells in the pancreas

41
Q

Glucagon

A

Another pancreatic hormone released by alpha cells in the pancreas

Mediates glycogenolysis– conversion of glycogen back into glucose when blood glucose levels drop

42
Q

Lipids

A

(or fats) for longer-term storage

Deposited in adipose tissue

43
Q

Under periods of longer food deprivation

A

gluconeogenesis kicks in to convert fat and proteins into glucose and ketones

44
Q

Insulin is required for:

A

getting glucose into cells to be used by the body

45
Q

Insulin is NOT required for:

A

glucose to be used by brain cells; and not required to make use of ready energy from fatty acids

46
Q

Why does the body need insulin?

A

To help glucose transporters import glucose from the blood into most cells

And to help monitor appetite

47
Q

Diabetes mellitus

A

Caused by the failure of insulin to induce glucose absorption

48
Q

Type 1 (juvenile-onset)

A

A failure of the pancreas to produce insulin

49
Q

Type 2 (adult-onset)

A

Primarily a consequence of reduced sensitivity to insulin

50
Q

Ventromedial hypothalamus (VMH)

A

Satiety center

51
Q

Lateral hypothalamus (LH)

A

Hunger center

52
Q

The _____ of the hypothalamus is key in integrating peptide hormone signals from the body

A

arcuate nucleus

53
Q

2 hormones in appetite control

A

Ghrelin
PYY3-36

54
Q

Ghrelin

A

Synthesized and released by endocrine cells of the stomach

Appetite stimulant

55
Q

PYY3-36

A

Released by intestinal cells; reaches high levels after you eat

Appetite-suppressant

56
Q

2 sets of neurons in appetite control

A

POMC neurons: inhibiting appetite and increasing metabolism

NPY neurons: hunger neurons; stimulating appetite and reducing metabolism

57
Q

Ghrelin and PYY3-36 act on NPY hunger neurons in opposition

A

Ghrelin stimulates them and increases appetite

PYY3-36 inhibits them and reduces appetite

58
Q

Nucleus of the solitary tract (NST)

A

Where appetite signals converge

Common pathway for feeding behavior

59
Q

Cholecystokinin (CCK)

A

peptide released by the gut after feeding and acts on the vagus nerve to inhibit appetite

60
Q

Leptin

A

Fat cells release leptin into the bloodstream to provide information to the brain about long-term energy reserves

Activates POMC neurons but inhibits NPY neurons, so leptin works to suppress hunger

61
Q

Defects in leptin

A

Cause overeating and obesity

Psych 230 exam 2 (7 decks)

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