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PAPER 4 BIOLOGY, (Normal body temp (37), Normal body temp (37)), (Normal…
PAPER 4 BIOLOGY
EXCRETION
Key Words & Definitions
Ureter- the tube connecting the kidney to the bladder
Bladder - Stores urine
Urethra - tube connecting bladder to exterior
Organs of excretion
Kidneys -Excretion of urea, water and mineral ions
Liver - urea (from amino acids)
Skin - Water + mineral ions
Lungs - carbon dioxide + water
HOMOESTAISIS
Key Words & Definitions
Homoestasis - mainenance of a constant internal environment
Set Limits - target values, such as the body temp of 37 degrees celcius
The Structure of the Skin
- Top Layer
-- Sweat Pore
- Epidermis
-- Free nerve ending (sensitive to pain and temperature)
- Dermis
-- Capillaries
-- Sweat glands
-- Hair roots + muscles
-- Sensory neurones
-- Arterioles
-- Touch and pressure receptors
- Fatty Tissue
- Muscles
Temperature Regulation by the SkinReceptors
- Regulation is controlled by the brain which contains receptors sensitive to the temperature of the blood
- The skin also has temperature receptors which send nervous impulses to the brain (via sensory neurones)
Response
- Brain then sends nerve impulses to effectors in the skin (sweat glands, blood capillaries)
(Fatty tissue acts as insulation to prevent heat loss through skin)
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HORMONES
Key Words & Definitions
Hormone - a chemical substance produced by a gland and carried by blood
Endocrine System - what the glands that produce hormones in animals are collectively known as
Major Endocrine glands in the body
Pituary gland - The 'master gland' at the base of the brain
Thyroid gland - produces thyroxine (processes fat)
Pancreas - produces insulin and glucagon but also digestive enzymes (amylaze and lipase)
Andrenal glands - makes adrenaline
Testes/ovaries - make testosterone/oestrogen
Transport around the body
Encocrine glands have a good blood supply to get the hormones into the blood stream (specifically plasma)
Hormones only affect cells with complementary target receptors that the hormone can bind to (found on cell membrane or inside cells)
Purpose of the liver
regulates hormones in the bloodstream, transforming or breaking down any excess
Zoom-in to Insulin
- Pancreas produces insulin
- Insulin released in the bloodstream
- Insulin attatches to the target cell of the target organ
- Stimulates the uptake of glucose to store in the form of glycogen
Zoom-in to Glucagon
- It is produced when blood glucose level falls to stimulate liver and muscle cells to convert stored glycogen into glucose and release it into the blood
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