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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

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
How does salt impact cells?
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
Two kinds of thirst
Osmotic thirst Hypovolemic thirst
27
Osmotic thirst
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
Hypovolemic thirst
Loss of volume of extracellular fluid
29
______ in the hypothalamus respond to changes in osmotic pressure as water is drawn out of cells by osmosis
Osmosensory neurons
30
Important brain regions in osmotic thirst
areas in the hypothalamus (POA, supraoptic nucleus, anterior hypothalamus) and the circumventricular organs
31
Circumventriuclar organs
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
Baroreceptors
Located in major blood vessels and the heart Detect drop in blood pressure
33
Remedy to osmotic thirst
Water
34
Remedy to hypovolemic thirst
Water and salts
35
Hypovolemia causes release of _____, or antidiuretic hormone (ADH)
Causes release of vasopressin From the posterior pituitary gland Induces blood vessel constriction and reduces water flow to the bladder
36
Renin
Kidneys release enzyme called renin to conserve water from hypovolemia Triggers other hormones, resulting in circulation of angiotensin II
37
Angiotensin II
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
Glucose
Principal sugar used for energy
39
Glycogen
Complex carbohydrate made by combining a bunch of glucose molecules and then storing it for a short time in the liver and muscles
40
Glycogensis
The process of converting glucose to glycogen, regulated by the pancreatic hormone insulin, released by beta cells in the pancreas
41
Glucagon
Another pancreatic hormone released by alpha cells in the pancreas Mediates glycogenolysis– conversion of glycogen back into glucose when blood glucose levels drop
42
Lipids
(or fats) for longer-term storage Deposited in adipose tissue
43
Under periods of longer food deprivation
gluconeogenesis kicks in to convert fat and proteins into glucose and ketones
44
Insulin is required for:
getting glucose into cells to be used by the body
45
Insulin is NOT required for:
glucose to be used by brain cells; and not required to make use of ready energy from fatty acids
46
Why does the body need insulin?
To help glucose transporters import glucose from the blood into most cells And to help monitor appetite
47
Diabetes mellitus
Caused by the failure of insulin to induce glucose absorption
48
Type 1 (juvenile-onset)
A failure of the pancreas to produce insulin
49
Type 2 (adult-onset)
Primarily a consequence of reduced sensitivity to insulin
50
Ventromedial hypothalamus (VMH)
Satiety center
51
Lateral hypothalamus (LH)
Hunger center
52
The _____ of the hypothalamus is key in integrating peptide hormone signals from the body
arcuate nucleus
53
2 hormones in appetite control
Ghrelin PYY3-36
54
Ghrelin
Synthesized and released by endocrine cells of the stomach Appetite stimulant
55
PYY3-36
Released by intestinal cells; reaches high levels after you eat Appetite-suppressant
56
2 sets of neurons in appetite control
POMC neurons: inhibiting appetite and increasing metabolism NPY neurons: hunger neurons; stimulating appetite and reducing metabolism
57
Ghrelin and PYY3-36 act on NPY hunger neurons in opposition
Ghrelin stimulates them and increases appetite PYY3-36 inhibits them and reduces appetite
58
Nucleus of the solitary tract (NST)
Where appetite signals converge Common pathway for feeding behavior
59
Cholecystokinin (CCK)
peptide released by the gut after feeding and acts on the vagus nerve to inhibit appetite
60
Leptin
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
Defects in leptin
Cause overeating and obesity

Psych 230 exam 2 (7 decks)

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