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28 Cards in this Set
- Front
- Back
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Fluid in the body needs to be regulated. What fluids are these? |
1) Intracellular Fluid (67%) 2) Extracellular Fluid (reservoir) - Interstitial fluid (26%) - Blood plasma (7%) - Cerebrospinal fluid (~1%) |
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What is the purpose of blood plasma in the body? |
It is critical to the heart. Without enough blood, the heart is unable to pump effectively - there is some flexibility but it is very limited. Too much plasma/pressure and blood vessels burst (bad) |
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What are the two types of thirst? |
Volumetric thirst Osmometric thirst |
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What is Osmometric thirst, and Volumetric thirst? |
O - Loss of intracellular water V - Loss of blood plasma Makes us thirsty so we seek out water (Behavioural). |
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What happens during osmometric thirst? |
There's not enough water in cells so they begin to shrink - this can be due to eating a salty meal. Specialist neurons are able to spot this (Verney, 1947). These are called osmoreceptors. |
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How do osmoreceptors detect a change? |
Due to losing fluid, the cell shrinks which causes a reduced firing rate, which tells the brain that it's time to drink. |
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Where are osmoreceptors in the brain? |
They are in the lamina terminalis. |
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What happens in the brain when the osmoreceptors fire slower? |
It is detected by the anterior cingulate cortex which causes motivational unpleasantness which is a forceful intrusion into consciousness. |
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What happens during volumetric thirst? |
There is a lack of blood plasma, which can be due to loss of blood (low BP), diarrhoea and vomiting. There has been a loss of salt within the fluid which causes a salt appetite. |
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What detects a change in blood plasma? |
Atrial barareceptors. They detect stretch and release Atrial Natrieretic Peptide (ANP). |
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What does Atrial Natriuretic Peptide do? |
Less stretch of blood vessels -> secrete less ANP. ANP inhibits drinking and boosts kidney activity (water excretion). Less -> more drinking Less -> less urine. |
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What is Vasapressin? |
A peptide hormone released by posterior pituitary gland. Anti-diuretic hormone (ADH) Instructs kidneys to reduce flow of water to bladder. |
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What happens if someone doesn't have ADH? |
Will just drink and release urine all of the time. |
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When is drinking triggered? |
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What is the use of the subfornical organ? |
The neurons detect angiotensin in the blood. |
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What 4 hormones are important to food regulation and satiety? |
Insulin Ghrelin (GH-Releasing) (Growth Hormone effects too) PYY3-36 (Pancreatic Peptid YY) |
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What is the role of insulin? |
Glucodetectors in the liver signal the Hypothalamus -> 'Nucleus of the solitary tract' (NST) If there is too much glucose present, insulin is released into blood. Cells then take glucose in to use and to store. |
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What is Leptin and it's role? |
A chemical secreted by well-nourished fat cells. Certain mice are unable to produce leptin due to a genetic mutation making them fat. Used to allow you to stop eating. |
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What is the role of Ghrelin? |
If the stomach is empty, it secretes Ghrelin. Ghrelin increases before meals. Levels drop immediately after a meal is eaten. |
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Where is Ghrelin injected if there is a problem? |
Just after the occipital horn, or the pointy bit. |
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What is the role of PYY3-36? |
Secreted by both small and large intestines. Low blood levels prior to meals. Injecting PYY3-36 curbs appetite in both humans and rats (Baynes et al., 2006). Opposite effect to Ghrelin. |
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Which hormones are longer term, and which are short term? |
Leptin and insulin are longer term. Ghrelin and PYY3-36 are short term. |
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What do the hormones do in terms of eating? |
Insulin -> Glucose -> Eat less Leptin -> Fat storage -> Eat less (Activate appetite suppression areas and inhibit appetite-increasing areas.) PYY3-36 -> Active intestines -> Eat less Acute (short-term control). |
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How does the body know when to stop eating? |
1] Short-term satiety - eyes; nose; mouth; food in gut (e.g. stomach) 2] Long-term satiety - fatty tissue |
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Which is worse; over or under-eating? And why? |
Starvation is worse than over-eating (fatal in short-term), evolutionarily more likely. Evolved to obtain/store food - eat when empty, not hungry Encourage three meals/day. |
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Why do weight loss programs not work? |
Most are unsuccessful due to: 1) weight loss is rapid 2) weight loss declines 3) weight loss halts 4) diet ends (rapid gain starts) 5) back to starting point |
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What are some individual differences? |
- Metabolic rate - Diet-induced Thermogenesis: (Heat production after eating, efficient DIT = weight gain. - Output (i.e. Exercise!) - Non-exercise activity (i.e. tapping) |
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What are the most common eating disorders? |
- Obesity (50% of USA) - Anorexia Nervosa (1.5%); evidence of abnormal AgRP levels (Moriya et al., 2006) Bulimia Nervosa (1.5%) Lack of nutrient reserves. |
