Homeostasis

What is Homeostasis?
The maintanence of a constant internal environment.
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Homeostasis ensures that the cells in the body can...?
Function normally, despite external factors, as they are in an environment which meets their needs.
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Homeostasis also protects --- which are key in metabolic reactions.
Enzymes
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Hoemostasis controls the...?
pH, temperature of the body, water potential and blood glucose levels.
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The contorl system of homeostasis is split into six steps. The first step is...?
A stimulus triggers a change in the variable (the element which is monitered and controlled by homeostasis).
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The second stage of the control system of homeostasis is...?
The change being detected by a receptor.
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The third stage of the control system of homeostasis is...?
Input; where the information (action potential) is sent along the afferent pathway to the brain.
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The fourth stage in the control system of homeostasis is...?
The control centre (brain) - the medulla oblongata recieves the action potential.
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The fifth stage of the control system of homeostasis is...?
Output; where the information is sent along the efferent pathway to the effector.
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The sixth stage of the control system of homeostasis is...?
The effector triggers a response which is fed back to the stimulus to return the variable to normal/maintain homeostasis.
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The afferent pathway is the...?
Sensory pathway
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The efferent pathway is the...?
Motor pathway
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Homeostasis increases heat loss by...?
Widening the blood vessels, to loose heat through radiation.
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Homeostasis decreases heat loss by...?
Contracting the blood vessels, to reduce the radiation of heat/heat loss through radiation.
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Homeostasis also increases heat loss through...?
Causing the body to sweat, which looses heat through evaporation.
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Homeostasis increases body temperature through...?
The uncoordinated shivering of the skeletal muscles, which increaes respiration and heat production.
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What are Ectotherms?
Organisms which do not regulate their own body temperature (cold blooded).
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What are Endotherms?
Organisms which do regulate their own body temperature (warm blooded).
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What is the first stage in controlling blood glucose levels, when the levels of blood glucose are too high?
High blood glucose levels are detected. (Stimulus)
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What is the second stage in controlling blood glucose levels, when the levels of blood glucose are too high?
The stimulus triggers an action potential which is sent to the CNS. This then triggers the release of insulin. (Effector)
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What is the thrid stage in controlling blood glucose levels, when the levels of blood glucose are too high?
β Glucose receptors in the pancreas detect the levels of gluocse and triggers the production of insulin.
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What is the fourth stage in controlling blood glucose levels, when the levels of blood glucose are too high?
The inuslin bonds with insulin receptors on the liver, and trigger the formation of glygogen from glucose through glycogenesis. This lowers the blood glucose levels.
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Glycogenesis is...?
The formation of glycogen from glucose.
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Gluconeogenesis is...?
The formation of new glucose from amino acids and glycerol.
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Glycogenolysis is...?
The break down of glycogen into glucose.
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What is the first stage in controlling blood glucose levels, when the blood glucose levels are too low?
Low blood glucose levels are detected. (Stimulus)
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What is the second stage in controlling blood glucose levels, when the blood glucose levels are too low?
α Glucose receptors in the pancreas detect the low levels of glucose and trigger the production of glucagon.
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What is the third stage in controlling blood glucose levels, when the blood glucose levels are too low?
Glucagon receptors on the liver trigger the break down of glygogen into glucose through glycogenolysis. This increases blood glucose levels.
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If blood glucose levels are still too low, what happens?
Gluconeogenesis occurs, where amino acids and glycerol are converted into glucose.
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Which hormone also monitors and controls blood glucose levels?
Adrenaline
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Adrenaline is a --- hormone.
Non-lipid-soluble
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Adrenaline binds to specific receptor proteins on the cell membranes of which organ?
Liver cell membranes.
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The binding of adrenaline triggers an associate --- to change shape.
Transmembrane Protein
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The change in shape of the transmembrane protein triggers...?
The activation of the enzyme Adenylate Cyclase.
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Adenylate Cyclase causes the conversion of ATP into...?
Cyclic AMP
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Cyclic AMP activates which protein?
Protein Kinase A
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Protein Kinase A, activates another enzyme, whcih triggers the conversion of...?
Glycogen into glucose, resulting in an increase in blood glucose levels.
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What is Type One Diabetes?
When the body doesnt produce insulin.
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What are the warning signs for Type One Diabetes?
Increased thirst and urination, constant hunger, extreme tiredness, weight loss and blurred vision.
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What is Type One Diabetes caused by?
Genetics, environmental factors and auto-immune factors.
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How can Type One Diabetes be managed?
Through insulin injections, oral medication, diet and exercise and blood glucose monitoring.
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What is Type Two Diabetes?
Where either the body doesnt produce enough insulin, or the body no-longer responds to insulin.
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What are the warning signs for Type Two Diabetes?
Fatigue, wounds healing slowly and pain or numbness in the hands or feet (extremities).
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What can Type Two Diabetes be caused by?
Lifestyle/Lifestlye choices, genetics and aging.
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How can Type Two Diabetes be managed?
Through diet and exercise, blood glucose monitoring and in some cases, insulin injections or oral medication.
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What is Hypoglycaemia?
Low blood glucose levels.
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What is Hyperglycaemia?
High blood glucose levels.
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What are the five stages of Osmoregulation?
1. Ultrafiltration, 2. Selective Reabsorption, 3. The Loop of Henle, 4. The Regulation of Ions, 5. The Collecting Tubule.
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What happens in Ultrafiltration?
High hydrostatic pressure forces small particles out of the blood in the Glomerulus into the Bowman's Capsule. These small particles rae called the filtrate.
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What is in the filtrate produced in the Glomerulus/Bowman's Capsule?
Water, Urea, Salt and Glucose.
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Through which blood vessel does the blood move into the glomerulus?
The afferent arteriole
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What happens in Selective Reabsorption?
Glucose is reabsorbed into the blood in the proximal convoluted tubule through facilitated diffusion and active transport. Some water is also reasorbed into the blood through osmosis, moving along the ψ gradient.
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Na+ is pumped out of the proximal convoluted tubule through active transport. Cl-, glucose and amino acids also leave here, but through...?
Co-Transport
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How much (as a percentage) filtrate is reabsorbed is in selective reabsorption?
85%
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What happens in the Loop of Henle?
The Loop of Henle increases water reabsorption through osmosis, due to the tissue surrounding the Loop of Henle becoming gradually more salty (thus having a lower ψ).
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The longer the Loop of Henle...?
The more water that is absorbed.
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Desert animals such as hamsters have very long Loops of Henle, in order to...?
Preserve as much water as possible.
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The descending limb of the Loop of Henle is ---, whilst the ascending limb is ---?
Permeable to water, impermeable to water.
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Na+ ions are pumped out of the ---, lowering the water potential and allowing water from the --- to fill the gap in the middle of the Loop of Henle.
Ascending limb, descending limb.
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As water is removed, the concentration of the filtrate...?
Increases
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If osmoreceptors in the blood detect low levels of water, then an action potential triggers the release of --- from the ---.
ADH, Pituitary Gland
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ADH stands for...?
Anti-Diarrhoetic Hormone
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ADH triggers the cells in the collecting tubule to open more --- in the membrane.
Aquaporins
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More aquaporins allows for a greater concentration of --- to move into the blood and out of the ---.
Water, Collecting Tubule
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The reabsorption of water in the collecting tubule results in...?
The concentration of the filtrate becoming even greater.
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This results in a ...?
Low volume, high concentration urine.
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Other cards in this set

Card 2

Front

Homeostasis ensures that the cells in the body can...?

Back

Function normally, despite external factors, as they are in an environment which meets their needs.

Card 3

Front

Homeostasis also protects --- which are key in metabolic reactions.

Back

Preview of the front of card 3

Card 4

Front

Hoemostasis controls the...?

Back

Preview of the front of card 4

Card 5

Front

The contorl system of homeostasis is split into six steps. The first step is...?

Back

Preview of the front of card 5
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