module 5 Chemical communication-regulation and homeostasis

Question 1

what is chemical communication?

Answer 1

hormones are released into their environment and can travel throughout the body to cells or the circulatory system

Question 2

where do chemical signals impact?

Answer 2

the impact of signals can have a local impact on a few cells in an immediate environment or can be distributed via the circulatory system to organs and cells throughout the body

Question 3

what are some of the main functions of the endocrine system?

Answer 3

• maintenance of homeostasis
• modulation of tissue development
• modulation of immune system functions

Question 4

what are local chemical signals?

Answer 4

• influence target cells and tissues that are close by

Question 5

how do all chemical signals move through the body?

Answer 5

through diffusion (high concentration to low)

Question 6

What is an example of a local chemical signal?

Answer 6

Histamine is a response to allergens that results in a runny nose or itchy eyes
*anti-histamines are allergy medicines that stop these symptoms

Question 7

are neurotransmitters a chemical signal? if so how?

Answer 7

yes! They are a special type of signal that is secreted from neurons, signal is released into a synapse and influences other neurons or effector cells

Question 8

what are the two types of neurotransmitters in chemical signalling and their function?

Answer 8

1. Acetylcholine = stimulates skeletal muscle contraction
2. Norepinephrine = excitatory and influences other neurons

Question 9

how are hormones distributed throughout the body and why is this essential?

Answer 9

• the endocrine system secretes hormones into the bloodstream which distributes them to the rest of the body
• this distribution allows for a whole body coordinated regulation of cell function in response to the chemical signal

Question 10

what is an example of a hormone that regulates the uptake of glucose?

Answer 10

insulin, insulin regulates the full body reuptake of glucose into skeletal muscle, fat, liver and other cells as a response to carbohydrate intake in the diet

Question 11

how does insulin regulate high blood glucose?

Answer 11

the pancreas releases insulin into circulation when blood glucose levels are high
insulin stimulates glucose uptake into the muscles and adipose tissue to bring the glucose levels back down

Question 12

what are water-soluble hormones?

Answer 12

• rapid intense responses for short duration,
• water-soluble, dissolve in blood
• require a membrane-bound receptor to be able to impact cell because can’t cross membrane

Question 13

what are lipid soluble hormones?

Answer 13

• need to be bound to proteins to enter water soluble circulatory system
• can pass through the cell membrane to the nucleus (receptors inside cell)
• slower to activate and long half-life

Question 14

what level do most hormones maintain and what regulates them

Answer 14

usually stay around the homeostatic level and negative feedback loops regulate them

Question 15

what are the three categories of inhibitory/stimulation signals

Answer 15

1. humoral
2. neural
3. hormonal

Question 16

what is a tropic hormone

Answer 16

a hormone that stimulates the release of another hormone

Question 17

what is a humoral signal

Answer 17

something that is being detected in the bodily fluids that influence the stimulation or inhibition of a hormone
eg: blood glucose

Question 18

what is a neural signal

Answer 18

neuron controls the release of a hormone from a gland, the AP stimulates the release of the neurotransmitter that stimulates the hormone secretion

Question 19

what is a hormonal signal

Answer 19

tropic hormones
- a hormone that stimulates the release of another hormone

Question 20

what is an example of a cycle of tropic hormone control of release

Answer 20

the hypothalamus secreates a hormone that influences the release of a hormone from the pituitary gland which influences the release of cortisol from the target endocrine cell and then goes to the target cell

Question 21

why don’t all cells respond to a circulating hormone similarly?

Answer 21

because receptors on target cells are specific to one type of hormone that they need, only one hormone can bind to this specific receptor
this means the cells we want to respond from a certain hormone will have the receptors

Question 22

what if a cell requires a strong/fast response to a particular hormone

Answer 22

there will be more receptors for the specific hormone on the cell enhancing the response to the chemical signal

Question 23

where are the receptors located?

Answer 23

for water-soluble hormones, the receptors are located on the cell membrane
for lipid-soluble hormones the receptors are located inside the nucleus

Question 24

what do lipid hormones often do in the nucleus

Answer 24

influence DNA to drive protein production
- direct impact on the level of transcription

Question 25

how long does it take for lipid hormones to influence DNA and how does this occur

Answer 25

- a very slow process that can take a couple of days, - the receptor complex in the nucleus binds to DNA, synthesis of mRNA, moves out the cell and the manufacturing of a polypeptide chain

Question 26

what occurs when a water-soluble hormone binds to the receptor on the cell surface?

Answer 26

the signal is then transmitted into the cell Hormone binding receptors activate G proteins this stimulates the production of cAMP which stimulates enzymes (protein kinases) and cellular response then phosphodiesterase inactivates cAMP

Question 27

what does cAMP do?

Answer 27

it is an intracellular mediator that activates protein kinases

Question 28

epinephrine signal response steps

Answer 28

- signal molecule (epinephrine) attaches to receptor outside of the cell G protein is activated by hormone-binding receptor G-protein stimulates Adenylyl cyclase to use ATP to create cAMP cAMP then activates enzymes (protein kinases) and there is a cellular response

Question 29

how do water soluble hormones have a quick response

Answer 29

the hormone signal is able to be amplified through multistep, multiple enzyme processes increase/stimulate enzymes or cell activity which leads to the fast response to one hormone signal

Question 30

describe homeostasis

Answer 30

Maintenance of constant environment in the body - variety of endocrine hormones maintaining variety of functions

Question 31

name 3 ions important in human physiology

Answer 31

Calcium Ca2+ Sodium NA+ Potassium K+

Question 32

how does water get in and out of the body?

Answer 32

enters: through foods and fluids we intake exits : regulate output through urine production, sweat production, or respiration (breathing)

Question 33

which type of chemical controls influence heart rate?

Answer 33

neural control - sympathetic and parasympathetic systems neural hormones - epinephrine both modify heart rate

Question 34

how does insulin modify blood glucose levels

Answer 34

influences the reuptake of blood glucose into a variety of cells, lipids fats muscle cells, which brings down blood glucose levels

Question 35

what is it called when stem cells become specific types of cells (like muscle cells?)

Answer 35

stem cells differentiate into specific cells

Question 36

what type of chemical signal is histamine?

Answer 36

paracrine signal that stimulates a function that is very local

Question 37

what are the 3 different specialized cell types secreted by the pancreas involved in nutrient regulation of the blood

Answer 37

1. alpha cells 2. beta cells 3. delta cells

Question 38

what do alpha, beta and delta cells secrete

Answer 38

1. alpha = glucagon 2. beta = insulin 3. delta = somatostatin

Question 39

why is insulin secreted by beta cells ?

Answer 39

stimulates reuptake of glucose from the blood to many different tissues

Question 40

why is glucagon secreted?

Answer 40

in response to low blood glucose, secreted by alpha cells

Question 41

what steps occur when blood glucose levels increase above homeostasis?

Answer 41

1) homeostasis disturbed 2) stimulus of - autonomic nervous system - parasympathetic stimulation of insulin secretion - digestive system stimulated - pancreas stimulated 3) response - effector muscles reuptake glucose from the blood and excess is converted to adipose 4) homeostasis restored

Question 42

what are the two portions of the adrenal glands?

Answer 42

outer - cortex inner - medulla

Question 43

what is the function of the adrenal medulla

Answer 43

secretes epinephrine and norepinephrine - ready body for physical activity (the sympathetic NS which is what causes our fight or flight response stimulates the release of this from the adrenal medulla)

Question 44

what are the main structural and functional differences of the posterior and anterior pituitary gland

Answer 44

posterior = under direct neural control from hypothalamus anterior = hormones secreted from hypothalamus influence release from AP-AP hormones often influence release of other hormones from other endocrine glands

Question 45

where are thyroid and parathyroid glands located

Answer 45

wrapped around the trachea just below the larynx

Question 46

role of thyroid gland/parathyroid gland

Answer 46

roles in modifying cellular metabolic rate and calcium homeostasis

Question 47

proccess of the secretion of the thyroid hormone

Answer 47

-starts at the hypothalamus and the pituitary -TRH (thyroid releasing hormone) is secreted by the hypothalamus and stimulates TSH secretion from the anterior pituitary -TSH will then stimulate the thyroid gland to secrete thyroid hormones (T3 and T4) -release and synthesis of thyroid hormones will increase only if the blood levels of TSH increase, and vice versa

Question 48

process of regulating blood Ca2+ levels

Answer 48

blood ca2+ increases too much this stimulates the parathyroid gland to decrease PTH secretion stimulates parafolicular cells to increase calcitonin secretion - response - effectors = decrease in bone reabsorption and decrease in ca2+ from intestine this return the ca2+ back down

Question 49

why is ca2+ important

Answer 49

- vital for muscle contractions -vital for neural signals

Question 50

what is the adrenal cortex?

Answer 50

the outer region of the adrenal glands secretes 3 classes of hormones

Question 51

what are mineralocorticoids

Answer 51

hormones that regulate blood ions (minerals)

Question 52

what is aldosterone

Answer 52

- a mineralocorticoid that is released when BP is low - it increases na+ reabsorption which causes water reabsorption (through osmosis) which returns bp back to normal

Question 53

what are glucocorticoids

Answer 53

regulate fuel availability through glucose & free fatty acids eg: cortisol - lipid breakdown due to stress

Question 54

what are the 3 classes of hormones released by the adrenal cortex?

Answer 54

1. mineralocorticoids 2. glucocorticoids 3. adrenal androgens

Question 55

what are adrenal androgens?

Answer 55

male secondary sex characteristics

Question 56

main difference between anterior and posterior pituitary

Answer 56

the axons of the hypothalamus extend down to the posterior pituitary, where they release neurohormone, whereas the anterior pituitary axons release into the hypothalamus into the circulatory system which leads to release in the anterior pituitary