Homeostasis Continued

Question 1

two states signal a need for water:

• high extracellular solute concentration stimulates
  …
• low extracellular volume from a loss of bodily fluids stimulates …

Answer 1

osmotic thirst

hypovolemic thirst

Question 2

occurs when the extracellular fluid becomes too salty

this results from 1) obligatory water loss (respiration and urination) or 2) eating salty foods

• in both cases, solute concentration increases, so water Is drawn out of cells by osmosis

Answer 2

osmotic thirst

Question 3

… in the brain (including cicumventricular organs) detect the increased concentration of extracellular fluid

Answer 3

osmosensory neurons

Question 4

are specialized brain structures that can monitor fluid balance, due to their location next to the ventricles

Answer 4

circumventricular organs

Question 5

salt is actually very important!

1. if there was no salt and only pure water outside cells, the water would be pushed into cells and they would burst
2. retaining salt in the extracellular space (and kidneys) is especially important for …

Answer 5

retaining water

Question 6

low extracellular volume from a loss of bodily fluids stimulates … the concentration of the fluid has not changes – salt and ions are also lost

Answer 6

hypovolemic thirst

Question 7

in blood vessels and the heart detect a drop in pressure

• the sympathetic nervous system causes arteries to constrict, and several hormone systems are activated
• the brain activates responses such as thirst and salt hunger (drinking water alone does not fix it)

Answer 7

baroreceptors

Question 8

peptide hormone from the posterior pituitary; acts on the kidneys to slow production of urine and increase water absorption; constricts blood vessels to increase blood pressure

Answer 8

vasopressin (AVP)

Question 9

A steroid hormone from the adrenal glands; stimulates kidneys to conserve sodium; contributes to increased salt appetite

Answer 9

aldosterone

Question 10

chemicals required for function, maintenance, and growth of the body

Answer 10

nutrients

Question 11

breaking down food – is controlled by the nervous system, which also anticipates future requirements

Answer 11

digestion

Question 12

there are also mechanisms that tell us when to stop, but they can be overcome by …

Answer 12

social factors

Question 13

is the principle sugar used for energy

Answer 13

glucose

Question 14

is glucose stored in the liver and muscles for the short-term, a process regulated by the pancreatic hormone insulin

Answer 14

glycogen

Question 15

when glucose levels drop, the hormone… converts glycogen back into glucose

Answer 15

glucagon

Question 16

for longer-term storage… molecules are stored in adipose tissue

• under prolonged foods deprivation, fat can be converted into glucose and ketones, which can be used as fuel

Answer 16

lipid (fat)

Question 17

the majority of food energy is used for… heat production, maintenance of membrane potentials, and life sustaining processes

• metabolism is tricky: you can reduce the number of calories you bring in, but your body will often reduce your metabolism as well, so your body weight may not decreases drastically

Answer 17

basal metabolism

Question 18

the body needs … to help glucose transporters import glucose from the blood into most cells

Answer 18

insulin

Question 19

results from the failure of insulin to induce glucose absorption

Answer 19

diabetes mellitus

Question 20

in … diabetes, the pancreas does not produce insulin

Answer 20

type 1 (juvenile-onset).

Question 21

… diabetes is caused by greatly reduced tissue sensitivity to insulin

• the brain can still use glucose, but the body can’t; it gets energy from fatty acids, while glucose builds up in the blood and can damage tissues

Answer 21

type 2 (adult-onset)

Question 22

… phase of insulin release is mediated by the brain in response to seeing, smelling or tasting food

Answer 22

the cephalic

Question 23

insulin is released again in the … phase, when food enters the digestive tract

Answer 23

digestive

Question 24

in the … phase specialized liver cells called glucodetectors signal the pancreas to release even more insulin

Answer 24

absorptive