5- Homeostasis And Response Flashcards
Homeostasis
Regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes
- controls
- blood glucose conc
- body temp
- water levels
Thermoregulation
- body temp is monitored and controlled by thermoregulatory centre in the brain
- thermoregularit centre contains receptors sensitive to temp of blood
What happens if body temp is too high
- above 40
- enzymes begin to denature
- digestion, respiration and oter chem reactions in bodies to keep organism alive affected
What happens if body temp too low
- below 35
- enzymes dont work as effecctively
- rate of reaction slower
Body response to body temp too high
- detected by skin temp receptors
- capillaries dilate (vasodilation)
- get bigger
- heat lost through skin s more blood passes through capillaries
- lots of sweat produced
- evaporation causes heat to be lost from skin
- hairs lie flat
Body response to body temp too low
- capillaries constrict (vasoconstriction)
- reduce blood flow, less heat loss through skin
- little/no sweat produced
- hairs pulled erect
- to trap insulating layer of air
- skeletal muscles contract-shiver
- releases heat due to increased respiration in muscle cells
Endocrine system
Made up of endocrene glands which secrete chemicals caled hormones into the blood stream
Hormone
- A chemical messenger produced in an endoxrine gland and is secreted by that gland
- travels in bloood stream to have an effect on another area of the body
Pituitary gland
- found in brain- little ball bit near front
- master gland- control all other glands
- controls growth
- stimulates thyroid, ovaries and testes
Pancreas
- next to stomach
- produces insulin
- control blood glucose
Thyroid
- bow tie in neck
- thyroxine
- controls metabolic rate
Adrenal gland
- above kidney
- adrenaliine
- flight or fight response
- responds to danger/excitement
Ovaries
- oestrogen
- controls menstrual system
- secondray sexual female characteristics
Testes
- testosterone
- controls sperm production
- male secondary sexual characteristcs
Nervous system vs hormones system
- hormoes slower
- hormones last for a long time
- hormones act in a more general way
- nerves act n a v.precise area
Osmoreguation
-kidneys maintaining optimum water and salt conc in blood and body
Ultrafiltration
-kidneys filter the blood under pressure
Why is osmoregulation important
- ensures body can function properly
- eg. Cooling, circulation, excretion
What happens if water conc too high
- water moves into cells b osmosis
- cells will burst
What happens if water conc too low
- water will leave cells into blood
- cels shrink and die
Body response to water conc increase
- hypothalamus detect change
- pituitary release less ADH
- less water reabsorbed from filtrate
- kidny nephrons less permeable
- lots of urine is produced and excreted
Body response to water conc too low
- hypothalamus detect change
- pituatary relase more ADH
- ADH targets kidney nephrons for collecting ducts to be more permeablle so more water reabsorbed
- less urine produced
Kidney failure
- kidneys can be damaged and destroyed by infections, accient or genetic problems
- toxins (eg. Urea) build up in body, mineral iona nd water balance of body not maintained
- cells can be damaged by osmosis
Negatives of dialysis
- carefully control proteiin intake- keep urea levels low
- control salt consumption- kidney cant remove excess mineral ions
- expensive NHS
- time consuking
- over time, more diff for dialysis to take place
- only short time when balance of chemicals correct
- tired and unwell until next session
Adv kidney transplant
- patient can live more normal life
- cheaper for nhs overall
- no controlled diet needed
Disadv kidney transplant
- shortage of organ donations
- kidney only lasts 8-9 years
- normal infection risk
- must take immuno suppressants for the rest of life to avoid rejection
- negative side effects
Main functions of kidneys
- remove waste products (eg. Urea from body)
- maintain water and salt balance in body -osmoregulation
- kidneys remove excess mineral ions and extrete them in urine
Selective reabsorption
- molecules removed from blood earlier reabsorbed int blood
- eg. Glucose, some water, some ions
Excretion
- body releasing and removing harmful waste products from the body hrough breathing, sweating and urinating
- lungs- co2 and water removed at lungs when breathing out
- skin- water, ions, urea are removed/excreted through the skin
Excretion in kidney
- urea produed by liver
- deammination- ammonia is produced as waste product of breaking down amino acids, converted into urea
- urea removed from blod by the liver
- urine stored in bladder
Gibberellins
-important in seed germination
Ethene
-controls cell division and ripening of fruits
Tropism
-growth movement towards or away from a stimulus(change in environment)
Positive phototropism
- in shoot
- auxin molecules accumulate/move to opposite side to the light source
- auxin molecles encourage cell elongation
- shoot grows longer on shaded side- shoot grows towards light source
Positive gravitropim
- root
- gravity
- auxin molecules gather on lower side
- auxin molecules in roots inhibits cell elongation meaning the root grows downwards/ direction of force of gravity
Negative gravitropism
- gravity
- shoot
- auxin molecules gather on lower side
- auxin in shoot encourages cell elongation meaniing the shoot grows upwatfs, against the direction of force of gravity
Glucose levels too high
- pancreas reavts
- insulin released from pancreas
- liver recieves insulin
- liver takes in glucose from blood stream and makes glucogen (glucose molecules together0
- glycogen stored in liver and muscles
Glucose levels too low
- pancrease monitors
- glucagon relased from pancreas
- liver recieves glucagon
- glycogen split up into glucose
- glucose released into blood stream
Type 1 diabetes
- pancreas fails to produce sufficient insulin
- uncontrolled high blood glucose levels
- treated with insulin injections
Type 2 diabetes
- body cells dont respond to insulin produced by pancreas
- obesity is a risk factor for type 2
- controlled with a carb- controlled diet and exercise regime
How can excess blood sugars cause death
- blood glucose levels too high- water conc too low
- due to osmosiis- water leave cell to increase water conc in blood
- cell can shrink and die- in brain- death
How can diabeted be controlled
Careful attention-prevent sharp spikes in glucose levels
Exercise- for fuel in respiration, blood glucose levels lowered due to excersise
Injecting insulin- insulin signals to liver to take glucose from bloodstream, liver converts and stores glucose as glycogen
Adrenaline
- reacts to danger/excitement stimulus
- increases heart rate and moves the blood away from the skin
- boosts the delivery of oxygen and glucose to brain and muscles
How body reacts to danger/exciteent stimulus
- hypothalamus stimulates adrenal glands (just above kindeys)
- adrenaline relased
- high blood adrenaline- body reacts w/ threat or excitement dealt with- no more stimulus
- hypothalamus stops stimulting adrenal glands
- adrenaline stopped being secreted
- low blood adrenaline levels (normal)
Thyroxine
- regulates metabolism- basal metabolic rate
- speed at which chemical reactions occur when at rest
- important in stimulating protein synthesis for growth and development
- negatibe feedback
Thyroxine levels too high
- hypothalamus spots thos
- stops stimulating pituitary gland
- pituitary gland stops stimulating thyroid gland
Thyroxine levels too low
- hypothalamus spots tis
- starts stimulating pituitaru gland
- whcih stimulates thyroid gland
- thyroxine released, level rises in blood
- basal metabolic rate rises
