Homeostasis

Question 1

What is homeostasis?

Answer 1

the tendency of biological systems to maintain relatively constant conditions in the internal environment while interacting with and adjusting to the external environment or changes within the system.

Question 2

what are the levels of homeostatic maintenance?

Answer 2

whole-body
organ system
organ
cellular

Question 3

list components of a feedback loop

Answer 3

variables
receptors
control centers
effectors
methods of communication

Question 4

compare/contrast positive and negative feedback

Answer 4

both respond to stimulus and affect the variable.
positive feedback responds to a change in one direction by causing additional changes in that direction. negative feedback counteracts the stimulus.

Question 5

what’s an example of a positive feedback loop?

Answer 5

blood clotting, lactation, orgasm, birth contractions

Question 6

what’s an example of a negative feedback loop?

Answer 6

insulin lowering blood glucose, sweating when it’s hot, shivering when it’s cold.

Question 7

define a feedback loop

Answer 7

a system used to control the level of a variable in which there is an identifiable receptor (sensor), control center (integrator or comparator), effectors, and methods of communication.

Question 8

define feedback variable

Answer 8

parameters that are monitored and controlled/affected by feedback system

Question 9

define feedback receptor

Answer 9

sensor that detects changes in the variable

Question 10

define feedback control center

Answer 10

integrator that compares variable to in relation to set point and signals effectors to respond.

Question 11

define feedback effector

Answer 11

executes necessary changes to variable

Question 12

define feedback method of communication

Answer 12

nerves, hormones or similar that permit communication between receptor and control center.

Question 13

define feedback cycle

Answer 13

any situation where a variable is regulated and the level of the variable impacts the direction in which the variable changes, even if the feedback components are not clearly defined.

Question 14

which feedback components initiate transfer of information?

Answer 14

receptor and control center

Question 15

which feedback components cause direct changes to the variable?

Answer 15

effector and initiation event (stimulus)

Question 16

define stimulus

Answer 16

a change in the environment

Question 17

define set point

Answer 17

the ideal level for a variable

Question 18

define feedback

Answer 18

a situation when the output or response of a loop impacts or influences the input or stimulus.

Question 19

what are some functions that require tight regulation of calcium levels?

Answer 19

heartbeat regulation
muscle contraction
enzyme activation
cellular communication

Question 20

which organ system regulates blood calcium homeostasis?

Answer 20

endocrine system: parathyroid and thyroid contain blood calcium receptors.

Question 21

how does the body correct low blood calcium?

Answer 21

parathyroid secretes parathyroid hormone.
hormone stops kideys from secreting calcium in urine AND causes osteoclast to break down bone tissue and release calcium.

Question 22

How do children’s bodies react to high blood calcium?

Answer 22

thyroid releases calcitonin. calcitonin prevents bone breakdown and causes kidneys to reabsorb calcium from filtrate and expel it in urine.

Question 23

do adults secrete calcitonin?

Answer 23

no.

Question 24

hypocalcemia can cause…

Answer 24

muscle spasms and heart malfunction

Question 25

hypercalcemia can cause...

Answer 25

heart malfunction, muscle weakness, and kidney stones.

Question 26

what synthesizes glycogen from excess blood glucose?

Answer 26

the liver and muscles cells.

Question 27

what causes glycogen to be catabolized back into glucose?

Answer 27

the pancreas releases the hormone Glucagon when blood glucose levels decrease.

Question 28

what stores glucose?

Answer 28

liver, muscle cells, fat tissue cells.

Question 29

what type of problem occurs when cell number is not regulated?

Answer 29

tumor

Question 30

what causes a fever (as regards feedback loops)

Answer 30

the body's temperature set point is increased as an adaptive physiological immune response. Caused by pyrogens - molecules that change the temp set point.

Question 31

what is the control center for body temperature?

Answer 31

the hypothalamus

Question 32

what are some things calcium ions are needed for?

Answer 32

blood clotting muscle contraction enzyme activation cellular communication

Question 33

how does vitamin D affect blood calcium levels?

Answer 33

lowers blood calcium levels. Vitamin D is formed by kidneys and increases absorption of Calcium from blood.