A2 Biology Hormones, Neurones, Liver and Kidney

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Insulin is produced by which cells?
Beta cells
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What are insulin's target cells?
Liver, muscle and adipose tissue
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Generally hormones are made by what type of tissue?
Specialist endocrine tissue
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The function of insulin is?
To store surplus glucose which is converted to glycogen via glycogenesis
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How much glycogen can an average liver store?
75-100g
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Which cells produce glucagon?
Alpha cells
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The function of glucagon is?
Secreted when glucose levels fall, it will initiate the breakdown of glycogen by enzymes
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Cause of type II diabetes?
The constant secretion of insulin causes cells and receptors to become less responsive so glucose concentration increases
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What are the islets of langerhans?
Alpha and beta cells
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Too much glucose in the blood is called...?
Hyperglycaemia
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Too little glucose in the blood is called...?
Hypoglycaemia
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Type I diabetes is usually caused by...?
The islets of langerhans being destroyed by a viral infection or an autoimmune response with bodys white blood cells destroying beta cells
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Risk factors of type II diabetes
Obesity, a diet high in refined sugar, family history, old age
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Where is the cardiovascular centre found?
Medulla oblongata
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The nerve that slows the heart rate is called...?
The vagus nerve
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The nerve that speeds up the heart rate is called...?
The accelerator nerve
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Where is adrenaline secreted from?
The adrenal medulla
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What do chemoreceptors detect?
A fall in pH caused by a rise in CO2
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Effects of adrenaline
Relax smooth muscle, increase heart rate, dilate pupils, stimulate conversion of glycogen to glucose, increase mental awareness, makes hair stand on end
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What are local messengers?
Chemicals that are released by many cell tpyes that have an effect on nearby cells
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The 2 categories of homeostasis?
Behavioural and internal
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What is homeostasis?
The maintenance of a stable internal environment within an organism, despite external changes
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Most homeostasis is achieved by a...?
Negative feedback loop
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What is a positive feedback loop?
Where a change stimulates receptors and the effectors causes further change away from the normal state
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What is oxytocin?
A hormone stimulated by stretch receptors during labour, secreted by the anterior pituitary gland
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Ectotherms
The same temperature as the environment
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Endotherms
Maintain a steady temperature , usually greater than the environment
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Where is the thermoregulatory centre?
The hypothalamus
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Vasodilation
More blood reaches the skin capillaries
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Vasoconstriction
When the temperature falls, blood returns to core tissue so heat isnt lost by radiation
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Sodium pumps will transport what?
2 K+ ions inside the axon and 3 Na+ outside the axon via active transport
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What are the ion leak channels for?
Let ions through via facilitated diffusion, maintaining the concentrartion gradient
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What protein is the thick filament made from?
Myosin
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What protein is the thin filament made from?
Actin also containing tropomyosin
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Excretion
Removal of metabolic waste from the body
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E.g. of metabolic waste
CO2, H2O or urea
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What is metabolism?
All chemical reactions occuring in cells
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What is de-amination?
Where surplus amino acids that have an amine group removed to make ammonia
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Amino acid + oxygen ----->
Ammonia + keto acid
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2NH3 + CO2 ------->
CO(NH2)2 +H2O
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Functions of the liver
Formation of urea, detoxification, synthesis of bile and cholestrol, maturation and destruction of red blood cells and regulation of blood sugar
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What do bile salts do?
Emulsify fats ( become small droplets) increasing SA:Vol for digestion by enzymes
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Excess glucose causes?
Osmotic stress
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Excess vitamin D
Elevated Ca, anorexia, nausea and kidney failure
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Excess iron causes?
Iron deposits in cells
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Excess vitamin A causes?
Can be fatal
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Bile contains:
HCO3-, bile salts, bile pigments, cholestrol
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Function of the renal artery
Carries 'unclean' blood in to the kidneys from aorta
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Function of renal vein
Carries clean blood away from kidney
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Function of urethral sphincta
Contracts to keep urine in bladder, relaxes to allow urination
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Function of Ureter
These tubes carry urine from kidneys to bladder
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What is ultrafiltration?
PLasma and soluble products are forced through fenestrations in capillary walls, larger products such as proteins and erythrocytes are too large to pass through
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Selective Re-absorption
Whilst these filtered products are passing through the proximal convoluted tubule, they are reabsorbed before reaching the loop of henle
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Molecules larger than ...... cannot pass through fenestrations
69000 RMM
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How much of the water is reabosrbed at the proximal convoluted tubule?
85%
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What do the tubule epithelial cells take up in the PCT?
Na+, amino acids, glucose via facilitated diffusion
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What are the carrier proteins that take up the molecules in the PCT called?
Co-transporter proteins
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Function of the loop of henle?
Fine tunes the ion/water content of the blood
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The thin descending loop is permeable to what?
permeable to water and partly permeable to Na+
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The thin ascending loop is permeable to what?
Na+ ions, impermeable to water
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The thick ascending loop is permeable to what?
Impermeable to water and slightly to Na+
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What receptors in the hypotalamus detect low water potential?
Osmoreceptors
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What secretes ADH?
Posterior pituitary gland
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ADH
Anti Diuretic Hormone
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Function of the distal convoluted tubule
Further balancing of water and ions
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Function of the collecting duct
The last place where reabsorption of water occurs, by passing through negative meddullary tissue so water leaves via osmosis
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What analysis method can be used to test urine?
Gas chromatography
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Chronic kidmey failure can be caused by:
Nephritis, damage due to high bp, diabetes, atherosclerosis, bacterial infection of pelvis
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Nephrons are destroyed leading to:
dilute urine, dehydration, salt imbalance, high bp, coma and convulsions
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Acute kidney failure is caused by:
sudden loss of blood, heart failure, toxic chemicals, damage to kidney
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Tissue rejection in transplants is reduced by use of what?
Immunosuppressants such as cyclosporin A
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Other cards in this set

Card 2

Front

What are insulin's target cells?

Back

Liver, muscle and adipose tissue

Card 3

Front

Generally hormones are made by what type of tissue?

Back

Preview of the front of card 3

Card 4

Front

The function of insulin is?

Back

Preview of the front of card 4

Card 5

Front

How much glycogen can an average liver store?

Back

Preview of the front of card 5
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