11 Flashcards
What is homeostasis?
Maintaining a constant internal environment
why do cells need homeostasis
vital for cells to function normally and prevent damage
example of control
core temperature
blood glucose
water balance
Morbidity
impaired quality of life leading to stress and disease
mortality
loss of life and death
Example of controlled body temp
37.5
Example of controlled blood glucose
3.5-5dm
Example of controlled oxygen level
12Kpa
Temperature jeopardised
Hyperthermia
Blood glucose jeopardised
Diabetes
Oxygen levels jeopardised
Hypoxia
Homeostasis involves negative feedback
what is it
mechanism that restores a level back to normal by reversing a change
Multiple negative feedback
Quicker response
More control
Positive feedback
amplifies change from a normal level
Triggers response to be MORE
Positive feedback Features
Not involved in homeostasis
Gives rapid activation of a process (e.g. labour)
Often associated with breakdown of control systems (e.g. temp. control)
What are hormones made of
protein
Where are hormones transported
bloodstream
Thermoregulation
Temperature of blood flowing through brain and and internal organs
Metabolism is controlled by temperature
Temperature changes enzyme activity
What happens if temperature state is too high
Hyperthermia
Brain becomes affected at 40degrees, begins showing symptoms such as confusion and hallucinations
41< leads to organ failure, denaturing of proteins, coma and death.
What happens if temperature state is too low ?
Hypothermia
Brain becomes affected at 34 degrees.
Confusion, loss of co ordination
When it is lower then 32degrees, brain damage and organ failure
Why is thermoregulation controlled?
To ensure enzymes are functioning correctly
- hyperthermia leads to denaturing of proteins
-hypothermia leads to slow rate of reaction
Epidermal response to hypothermia
Insulating layer of air above the skin
Little/no sweat produced
As the muscles contract to pull the hairs upright, a tiny bulge appears on the skin – ‘goosebumps’.
Epidermal response to hyperthermia
Sweat evaporated from skin increasing heat loss
Sweat glands produce sweat
Hairs lie flat
Blood glucose regulation
- Blood supplies cells with glucose used as a substrate for respiration
- If there is not enough blood glucose the cell cannot perform respiration
- If blood glucose conc. is to too high the water potential of the blood falls so low that water leaves cells by osmosis, down the water potential gradient. If too much water leaves cells, they shrivel up (crenate) and die.
Blood glucose too low
Cells lose water by osmosis, shrivel and die
Blood glucose too high
Cells cant make enough ATP to stay alive
Hypoglacaemia
Fainting
Loss of conciousness
How is an increase in blood glucose regulated
Beta cells secrete insulin
Reducing BG
Binding to liver/muscle cells
More glucose enters cells
Stimulates glucose - glycogen
How is a decrease in BG regulated?
alpha cells detect and secrete glucagon
increasing bg
binds to liver cells
Functions of the kidney
Excretion of Urea - from the body
Osmoregulation - Control of water and salt levels
Bowmans capsule and ultrafiltration
Ultrafiltration occurs under high pressure.
Blood pressure in the glomerulus capillaries is unusually high because:
Afferent arteriole is wider than the Efferent arteriole
Bowmans capsule and ultrafiltration
Ultrafiltration occurs under high pressure.
Blood pressure in the glomerulus capillaries is unusually high because:
Afferent arteriole is wider than the Efferent arteriole
What are pores
Pores are holes in the capillary wall.
These allow blood plasma & dissolved solutes through.
