5.1 Homeostasis and 5.3 Hormonal control

Question 1

Homeostasis definition

Answer 1

maintaining a relatively sonstant internal environment for optimum cell functioning

Question 2

endocrine system—hormones

Answer 2

• made of glands that secrete hormones directly into the blood stream
• hormones then are carried to target cells where they produce an effect
• hormones only affect certain tissues or organs because only the cells of that tissue or organ have special chemical receptors for that particular hormone

not as quick to respond to stimuli as the nervous system because uses speed of blood instead of speed of electricity
but responses have generally a longer lasting and more widespread effect

Question 3

Thyroxine

Answer 3

produced by thyroid gland, controls basal metabolic rate, kept stable due to thyroid stimulating hormone TSH

Question 4

Thyroxine level rises

Answer 4

(coordinator) change detected by hypothalamus
(response) which sends signal to pituitary gland which releases less TSH
stimulates thyroid gland to release less thyroxine
thyroxine levels fall

Question 5

Thyroxine levels fall

Answer 5

(coordinator) change detected by hypothalamus
(response) which sends signal to pituitary gland which releases more TSH
stimulates thyroid gland to release more thyroxine
thyroxine levels rise

Question 6

how might an overactive thyroid affect people

Answer 6

anxiety
hyperactivity
insomnia
weight loss
diarrhoea

Question 7

how might an underactive thyroid affect people

Answer 7

tiredness
feeling cold
weight gain

Question 8

adrenaline

Answer 8

not controlled by negative feedback loop

increases heart rate
increases breathing rate
stored by glycogen converted to glucose by the liver
pupils dilate
blood diverted from digestive system to large muscles

Question 9

how does increased heartrate help us deal with stressful situations

Answer 9

provides more oxygen and glucose to respiring muscles (to run)

Question 10

how does increased breathing rate help us deal with stressful situations

Answer 10

provides more oxygen to respiring muscles—run!

Question 11

how does stored glycogen converted to glucose by the liver help us deal with stressful situations

Answer 11

provides mroe glucose to respiring muscles—run!

Question 12

how does pupil dilation help us deal with stressful situations

Answer 12

improves eyesight by letting more light into the eye so you can —run! safely

Question 13

how does blood diverted from digestive system to large muscles help us deal with stressful situations

Answer 13

more glucose and oxygen for respiring muscles—run!

Question 14

blood glucose concentration

Answer 14

pancreas acts as cooridnator and effector—contains receptors which are sensitive to glucose so it can detect chagnes in blood glucose concentration

insulin—allows glucose into cells
glucagon—released when glucose has ‘gone’

Question 15

blood glucose concentration negative feedback loop:
blood glucose level rises

Answer 15

change detected by receptors in pancreas
pancreas releases INSULIN
causes glucose to enter cells
and be stored as GLYCOGEN in the liver
blood glucose level falls

Question 16

blood glucose level falls

Answer 16

change detected by receptors in pancreas
pancreas secretes GLUCAGON into the blood
liver breaks down glycogen
and releases glucose into the blood
blood glucose level rises

Question 17

diabetes symptoms

Answer 17

excessive frquent urination
thrush/genital itching
blurred vision/vision problems
excessive tiredness
excessive thirst
slow healing of wounds
weightloss

Question 18

diabetes table
type of diabetes, cause, typical onset, treatment(s)

Answer 18

type 1; no insulin made/released; childhood; insulin injections, reducing carbs in diet
type 2; cells do not respond to insulin; adulthood; diet (low carb), incr exercise, medications

Question 19

managing type 1 diabetes

Answer 19

glucose sensitivity sticks:
small plastic strips that have chemical attached to them that reacts with blood glucose and changes colour—colour reflects the concentration of glucose in a sample of blood/urine, not accurate/convenient, colour may be hard to see due to colour of urine

glucometer:
measures concentration of glucose in a small sample of blood

continuous glucose monitor:
wearable device with small needle inserted into the skin that continuouslyu monitors the concentration of glucose in blood, connected with sensor/phone

Question 20

curing type 1 diabetes

Answer 20

pancreas implant—risk of rejection, big operation, a lifetime of anti rejection drugs, permanent cure
transplanting pancreatic cells—no rejection, not permanents/needs to be replaced

Question 21

how can type 2 diabetes be treated

Answer 21

reduce carbs in diet
take medicaiton to increase insulin sensitivity
exercise to reduce BMI

Question 22

waste product excretion tbale
waste product, production, why they must be removed, removal

Answer 22

CO2, respiration, acidic when dissolved, lungs(alveoli)
urea, liver (deamination), highly toxic, kidneys
water and mineral ions; excess from diet, water is made from respiration; osmotic effects (bursting or shrivelling);kidneys

Question 23

kidney role

Answer 23

1. excretion—removal of urea from blood
2. osmoregulation—regulate the water and mineral ion content of blood

processes
1. filtration:
water, glucose, urea and mineral ions move out of the blood into the nephron. blood cells and proteins are too big to pass across and so remain in the blood

2. selective reabsorption:
   all glucose is reabsorbed from the filtrate by a combo of diffusion and active transport
   some water reabsorbed via osmosis , some mineral ions reabsorbed via diffusion and active transport
3. excretion
   all urea exccreted and excess ions and water, forms urine and is passed to the bladder via the ureter

Question 24

contorl of water balance—osmoregulation
blood water content rises

Answer 24

change detected by the hypothalamus
decreases ADH released by the pituitary galnd
permeability of kidney tubule decreases
less water is reabsorbed, increases volume of urine made

Question 25

blood water content falls

Answer 25

change detected by the hypothalamus
increases ADH released by the pituitary gland
increases permeability of kidney tubule
more water is absorbed, decreases volume of water/urine made

Question 26

blood water content falls

Answer 26

change detected by the hypothalamus
increases ADH released by the pituitary gland
increases permeability of kidney tubule
more water is absorbed, decreases volume of water/urine made

Question 27

how does dialysis work

Answer 27

blood leaves the body via synthetic tubing
passes alongside dialysis fluid, separated by a partially permeable membrane
all urea, some water, some mineral ions but no glucose diffuse out

Question 28

advantages of dialysis and kidney transplants

Answer 28

dialysis: keep patient alive until more permanent treatment
transplant: permanent cure, no need to restrict diet, no need for dialysis

Question 29

disadvantages of dialysis and transplants

Answer 29

dialysis:
takes 8 hours, several times a week
requires needle in skin repeatedly—risk of infection
diets musdt be managed—low protein, low salt
inconvenient and time consuming
urea builds up between sessions—will still feel ill
expensive for NHS—long term treatment

transplant:
risk of infection bc surgery
risk of rejection expecially if it’s not a close tissue match
must take immuno suppressants—more likely to get ill
general anaesthetic carries risk

Question 30

comparison between nervous system and endocrine system table
comparison, nervous sytem, endocrine system

Answer 30

speed of action: rapid acting, slower acting
nature of message: electrical transmission by nerve impulses and chemical transmission at the synapses, chemical transmission through the blood
duraiton of response: shorter (until electrical impulses stop), longer (until hormone is broken down)
area of response: specific muscle of gland, trage calls in particular tissues/organs (must have correct hormone receptors)