B12 - Homeostasis in Action Flashcards
What is body tempertaure controlled by?
The thermoregulatory centre in the hypothalamus
How is a change in body temperature detected
- Thermoregulatory centre in the hypothalamus monitor internal body temp
- Skin receptors monitor surface body temp
How does the body transfer more heat to the surroundings (cool down)
- Vasodilation to bring more blood to skin - heat is lost by radiation
- Sweating - sweat glands release water which has heat energy in it, when it evaporates, it takes the heat energy with it and cools the skin
What is sweat made of
A mixture of urea, water and mineral ions
How does the body reduce heat transfer/heat up
- Vasoconstriction
- Shivering - skeletal muscles contract and relax quickly releasing heat from respiration
- Sweat production is slowed
- Hairs stand on end - traps layer of insulating air
Waste products produced by the body (4)
- Urea from amino acid breakdown - toxic
- Carbon dixoide from respiration
- Water - affetcs osmosis
- Mineral ions - affects osmosis and diffusion
Why does carbon dioxide need to be removed from the body
It lowers blood pH so affects enzyme function
How is CO₂ removed
- Diffuse out of cells into blood plasma
- Diffuses from plasma into alveoli
- Exhaled by respiratory system
How is urea produced
From the breakdown of excess amino acids
* Amino acids —> ammonia
* ammonia + CO₂ —> urea
Name for the breakdown of amino acids and where does this process happen
Deamination in the liver
Uncontrolled methods of removing water and mineral ions
- Water - exhalation
- Mineral ions - sweat
Controlled removal methods
Kidneys through urine
How do the kidneys work? (4)
- All solubles pass from blood into kindneys
- Blood cells and proteins stay as they are too large
- All glucose is immediately reabsorbed
- No urea is reabsorbed
- The exactn amount of water and mineral ions reabsorbed is controlled by selective reabsorbtion based on the body’s needs
Where is ADH produced and stored
Produced in the hypothalamus and stored in the pituitary gland
What does ADH control
The amount of water reabsorbed from the kidneys. It does this by making the kidney tissues more water permeable
What happens when the water concentration is too low
- Detected by the hypothalamus
- Pituitary secretes ADH
- Tubules become more water permeable allowing more water back into blood
- Urine volume is low and concentrated
What happens when the water concentration is too high
- Detected by the hypothalamus
- Pituitary secretes LESS ADH
- Tubules become less water permeable allowing less water back into the blood
- Urine volume is high and dilute
Methods of reducing kidney rejection
- Tissue matching with a close family member
- Immunosuppresant drugs - risk of other infections
Advantages of kidney dialysis
- Readily available
- Relatively normal lifestyle
Disadvantages of kidney dialysis
- Long dialysis sessions
- Long term dialysis damages body
- Special diet
- Expensive
- Risk of blood clots and infections
Advantages of kidney transplant
- Better survival rates
- Near normal lifestyle
Disadvantages of kidney transplant
- Risk of rejection and therefore immunosuppresants
- More susceptible to other infections
- Regular check ups
Which parts of the blood don’t go into the kidneys?
Blood cells and plasma proteins
Basic steps in kidney dialysis
- PAtient attached to dialysis machine and their blood flows into it
- The dialysis fluid contains the optimum amount of solubles
- Blood passes over a partially permeable membrane with dialysis fluid on other side
- This allows urea and excess solubles to leave the blood
Why are the kidneys imporant in homoestasis
- Remove urea and toxins so cells don’t get poisoned or damaged
- Removes excess water and mineral ions to prevent osmotic damage
