5.1 Homeostasis and 5.3 Hormonal control Flashcards
Homeostasis definition
maintaining a relatively sonstant internal environment for optimum cell functioning
endocrine system—hormones
- 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
Thyroxine
produced by thyroid gland, controls basal metabolic rate, kept stable due to thyroid stimulating hormone TSH
Thyroxine level rises
(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
Thyroxine levels fall
(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
how might an overactive thyroid affect people
anxiety
hyperactivity
insomnia
weight loss
diarrhoea
how might an underactive thyroid affect people
tiredness
feeling cold
weight gain
adrenaline
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
how does increased heartrate help us deal with stressful situations
provides more oxygen and glucose to respiring muscles (to run)
how does increased breathing rate help us deal with stressful situations
provides more oxygen to respiring muscles—run!
how does stored glycogen converted to glucose by the liver help us deal with stressful situations
provides mroe glucose to respiring muscles—run!
how does pupil dilation help us deal with stressful situations
improves eyesight by letting more light into the eye so you can —run! safely
how does blood diverted from digestive system to large muscles help us deal with stressful situations
more glucose and oxygen for respiring muscles—run!
blood glucose concentration
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’
blood glucose concentration negative feedback loop:
blood glucose level rises
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
blood glucose level falls
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
diabetes symptoms
excessive frquent urination
thrush/genital itching
blurred vision/vision problems
excessive tiredness
excessive thirst
slow healing of wounds
weightloss
diabetes table
type of diabetes, cause, typical onset, treatment(s)
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
managing type 1 diabetes
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
curing type 1 diabetes
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
how can type 2 diabetes be treated
reduce carbs in diet
take medicaiton to increase insulin sensitivity
exercise to reduce BMI
waste product excretion tbale
waste product, production, why they must be removed, removal
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
kidney role
- excretion—removal of urea from blood
- 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
- 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 - excretion
all urea exccreted and excess ions and water, forms urine and is passed to the bladder via the ureter
contorl of water balance—osmoregulation
blood water content rises
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
blood water content falls
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
blood water content falls
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
how does dialysis work
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
advantages of dialysis and kidney transplants
dialysis: keep patient alive until more permanent treatment
transplant: permanent cure, no need to restrict diet, no need for dialysis
disadvantages of dialysis and transplants
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
comparison between nervous system and endocrine system table
comparison, nervous sytem, endocrine system
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)
