Nerves & Homeostasis

Question 1

What is the stimulus response pathway?

Answer 1

stimulus
receptor
coordinator
effector
response

Question 2

What are examples of stimuli and receptors?

Answer 2

light - eye
pressure - skin
chemicals - nose/tongue
heat - skin
sound waves - ears

Question 3

What is between the receptor and the coordinator?

Answer 3

sensory neuron

Question 4

What features does the sensory neuron have?

Answer 4

• dendrites - receive signal & set up impulse
• cell body - contains nucleus
• axon terminals - forms synapse with next neuron
• axon - carries impulse
• myelin sheath - insulates

Question 5

What are examples of the coordinator?

Answer 5

brain/spinal chord

Question 6

What is at the coordinator?

Answer 6

relay neuron - connects neurons via synapses

Question 7

What features does the relay neuron have?

Answer 7

dendrites
cell body
axon terminals

Question 8

What is between the coordinator & affector?

Answer 8

motor nueron

Question 9

What features does the motor neuron have?

Answer 9

dendrites
cell body
axon
myelin sheath
axon terminals
neuromuscular junction
muscle

Question 10

What are examples of the effector?

Answer 10

muscles/glands

Question 11

What are reflexes?

Answer 11

unconscious rapid reaction to stimulus

Question 12

How is the reflex quick?

Answer 12

it goes via spinal chord

Question 13

How do synapses work?

Answer 13

1. impulse arrives at axon terminal
2. vesicles containing neurotransmitter move toward cell membrane
3. neurotransmitters diffuse across synapse
4. neurotransmitter bind to receptor
5. new impulse is sent along next neuron

Question 14

What are the 2 types of gland?

Answer 14

• endocrine - releases hormones into blood (e.g. adrenal gland)
• exocrine - releases substances into digestive system or outside body (e.g. salivary gland)

Question 15

What happens if blood glucose is too high?

Answer 15

• increases (after meal)
• detected by pancreas
• insulin travels to liver & muscles
• liver & muscles absorb more glucose from blood, absorbed glucose stored as glycogen
• blood glucose decreases
• resting blood glucose returns (70-100mg/dm3)

Question 16

What happens if blood glucose is too low?

Answer 16

• tiredness (reduced respiration) can lead to coma (hypoglycemia)
• decrease (after fasting/exercise)
• detected by pancreas
• pancreas releases glucagon into blood
• glucagon travels to liver
• liver breaks glucagon to glucose, released in blood
• blood glucose increases
• resting blood glucose returns (70-100mg/dm3)

Question 17

What do hormones do?

Answer 17

bind to specific receptors on cells of target organs, travel through blood, can have multiple targets

Question 18

What glands are there?

Answer 18

pituitary gland
thyroid
adrenal gland
pancreas
ovaries
testes

Question 19

What hormones does the pituitary gland produce?

Answer 19

• FSH - stimulates egg maturation
• LH - stimulates ovulation in females
• ADH - controls water content in blood

Question 20

What hormones does the thyroid produce?

Answer 20

thyroxine - controls bodys metabolic rate

Question 21

What hormones does the adrenal gland produce?

Answer 21

adrenaline - prepares body for physical activity (flight/fight)

Question 22

What hormones does the pancreas produce?

Answer 22

• insulin - lowers blood glucose
• glucagon - raises blood glucose

Question 23

What hormones does the ovary produce?

Answer 23

• oestrogen - controls development of female secondary sexual characteristics
• progesterone - regulates menstrual cycle

Question 24

What hormones does the testes produce?

Answer 24

testosterone - controls development of male secondary sexual characteristics

Question 25

What happens when adrenaline is released?

Answer 25

- increases heart rate - increases breathing rate - diverts blood to muscles - increases blood glucose - pupils dilate - diverts blood away from digestive system

Question 26

What is diabetes mellitus?

Answer 26

decrease in ability to absorb glucose from blood, elevates blood glucose

Question 27

Why does diabetes mellitus type 1 happen?

Answer 27

pancreas produces less/no insulin

Question 28

Why does diabetes mellitus type 2 happen?

Answer 28

body doesn't respond well to insulin

Question 29

What is hoemostasis?

Answer 29

maintenance of body conditions within narrow limits

Question 30

What happens if you are too hot?

Answer 30

37C normally in humans enzymes denature - chemical reactions in body slow down

Question 31

What happens if you are too cold?

Answer 31

37C normally in humans enzymes work at suboptimum rate

Question 32

What happens if your blood is too concentrated?

Answer 32

water moves out of cells - shrivel up & don't function well

Question 33

What happens if you blood is too dilute?

Answer 33

water moves into cells and they can swell up & lyse (pop)

Question 34

What is blood concentration?

Answer 34

concentration of dissolved solutes

Question 35

What happens if blood glucose is too low?

Answer 35

feel tired/lethargic/coma not enough glucose for respiration

Question 36

What happens if blood glucose is too high?

Answer 36

increases concentration of blood, water drawn from tissues increased urine volume

Question 37

How does your body respond with homeostasis to being too hot?

Answer 37

- sweat - produced by sweat glands, water evaporates from skin, cooling body - vasodilation - blood flow directed to skin to increase heat loss - hair lies flat - increases heat loss from skin

Question 38

How does your body respond with homeostasis to being too cold?

Answer 38

- hair stands on end - traps layer of air - good insulator - reduces heat loss - vasodilation - blood diverted away from skin to prevent heat loss - shivering - rapid muscle contractions - increased respiration in muscles, releases thermal energy