Ch. 9- Internal Regulation Flashcards
What affects many aspects of behaviour? For example, activity levels, sleep-wake cycles.
Temperature.
What is vital to normal functioning?
Temperature regulation.
What does temperature regulation allow?
Normal functioning.
What is homoeostasis?
Maintenance of a set point.
Explain a set point, what it is related to, and some examples.
A single value that the body works to maintain, homoeostasis, and water, oxygen, glucose etc. levels.
What does poikilothermic mean?
The idea that the body temperature matches the environment.
What does ectothermic mean?
The idea that the body temperature matches the environment.
When would an organism become poikilothermic?
When it lacks the internal, physiological mechanisms of temperature regulation.
How is poikilothermic temperature regulation achieved?
Choosing locations in the environment.
What is an example of a poikilothermic animal?
Lizards, other cold-blooded animals.
What does homoeothermic mean?
Use of internal physiological mechanisms to maintain an almost constant body temperature.
What does endothermic mean?
Use of internal physiological mechanisms to maintain an almost constant body temperature.
What does homoeothermic temperature regulation require?
Energy and fuel.
How do homoeothermic animals increase and decrease temperature?
Sweating and panting to decrease temperature, and increasing temperature via shivering, decreasing blood flow, and increasing insulation.
What temperature did mammals evolve to maintain?
Roughly 37 degrees.
Why is an even temperature an advantage for mammals?
Muscle activity benefits from warmth.
If muscle activity benefits from warmth, why aren’t mammals warmer? (2)
Maintaining a higher body temperature increases energy demand, and proteins in the body break their bonds and lose their useful properties at higher temperatures.
What areas of the brain control temperature?
Pre-optic area (POA), and the anterior hypothalamus (AH).
What do the POA and AH control?
Controls panting, sweating and shivering.
What do the POA and AH receive input from? (2)
Temperature receptors in the body and the immune system.
How can the body conserve water? (3)
Excreting concentrated urine, decreasing sweat, and drinking more water than the body needs and excreting the rest.
What is vasopressin?
A hormone released by the posterior pituitary.
What does vasopressin do?
Raises blood pressure by constricting blood vessels, compensates for decreased water volume.
What is vasopressin also known as?
The anti-diuretic hormone (ADH).
What does vasopressin allows the kidneys to do?
Reabsorb water and excrete highly concentrated urine.
What are the two types of thirst?
Osmotic and hypovolemic thirst.
Explain osmotic thirst.
Results from eating salty food.
Explain hypovolemic thirst.
Results from loss of fluids due to bleeding or sweating.
How does osmotic thirst work?
Solutes inside and outside a cell create osmotic pressure, causing water to flow across a semi-permeable membrane from an area of low solute concentrations to an area of high solute concentration.
When does osmotic thirst occur?
When solutes are more concentrated on one side of the membrane than the other.
What is the normal concentration of solutes?
0.15 M
How does the brain detect osmotic pressure? (4)
Receptors around the third ventricle, the organum vasculosum laminae terminalis (OVLT), the sufornical organ, and receptors in the periphery, like the stomach and digestive tract.
What do the OVLT and subfornical organ do?
Detect osmotic pressure and sodium content of the blood.
How is hypovolemic thirst triggered?
By the release of the hormones vasopressin and angiotensin II.
What do angiotensin II and vasopressin do?
Constrict blood vessels to compensate for a drop in blood pressure.
What do neurons in the third ventricle do in relation to angiotensin II?
Send messages to the hypothalamus.
Why do predators have large digestive systems?
Because they’re adapted to huge, infrequent meals.
How often do bears eat?
Constantly.
Why do small birds eat only what is needed in the moment?
To preserve light weight for flight.
What percentage of their body weight do Chickadees eat daily?
10%, but they lose it all at night keeping warm.
What is the function of the digestive system?
To break down food so it can be used.
Where does digestion begin?
In the mouth, with saliva.
What happens to proteins in the stomach?
The hydrochloric acid and enzymes digest them.
What happens in the small intestine?
Enzymes digest proteins, fats, and carbohydrates. which are then absorbed into the bloodstream.
What does the large intestine absorb?
Water and minerals.
What are oral factors in feeding?
The desire to taste and chew, like chewing gum, are motivating factors in hunger.
Do sham feeding experiments produce satiety?
No.
What is the main signal to stop eating?
Stomach distension.
What does the vagus nerve do?
Conveys information about the stretching of the stomach walls to the brain.
What are the splanchnic nerves?
Nerves that convey information about the nutrient contents of the stomach.
What is the duodenum?
Part of the small intestine, which is the site of initial absorption of nutrients.
What, related to the duodenum, can produce feelings of satiety?
Distension.
What hormone does the duodenum release?
Cholecystokinin (CCK)
What does cholecystokinin regulate?
Hunger.
What is glucose? (3)
The main product of digestion, an important source of energy for the body, and nearly the only fuel used by the brain.
What do insulin and glucagon regulate?
The flow of glucose into cells.
What happens to excess glucose?
Enter the liver and fat cells.
What is insulin?
A hormone released by the pancreas.
What does insulin do?
Allows glucose to enter cells.
Explain the first change after a meal.
Blood glucose levels fall.
Explain the second change after a meal.
Insulin levels drop.
Explain the third change after a meal.
Glucose enters cells more slowly.
Explain the fourth change after a meal.
Hunger increases.
Explain the fifth change after a meal.
The pancreas releases glucagon.
What is glucagon?
A hormone released y the pancreas when glucose levels fall.
What does glucagon do?
Stimulates the liver to convert some of its stored glycogen to glucose.
Why does the liver convert stored glycogen to glucose?
To replenish low supplies in the blood.
How is long-term hunger regulation accomplished?
Monitoring fat supplies in the body.
What peptide do the body’s fat cells produce?
Leptin.
What does leptin do?
Signal the brain to increase or decrease eating.
What do low levels of leptin do?
Increase hunger.
What do high levels of leptin do?
Reduce eating and increase physical and immune system activity.
What is the arcuate nucleus?
The master area for controlling appetite.
Where does the arcuate nucleus receive information from?
All parts of the body.
What is the arcuate nucleus a part of?
The hypothalamus.
What types of neurons does the arcuate nucleus contain?
Neurons sensitive to hunger signals, and neurons sensitive to satiety signals.
What is ghrelin?
A neurontransmitter released in the brain that acts on the hypothalamus to increase appetite.
What does gherlin do?
Triggers stomach contractions.
What neurotransmitter has a relationship with obesity?
Ghrelin.
What are satiety signals?
Input to the satiety sensitive cells of the arcuate nucleus.
What does blood glucose stimulate?
Satiety cells in the arcuate nucleus.
What does body fat release and what does that stimulate?
Leptin, which stimulates satiety neurons.
Where does output from the arcuate nucleus go?
The paraventricular nucleus in the hypothalamus.
What does the paraventricular nucleus inhibit?
The lateral hypothalamus.
What delivers an excitatory message to the paraventricuar nucleus?
Axons fro the satiety sensitive cells of the arcuate nucleus.
What do melanocortins do?
Limit food intake.
What do cells in the lateral hypothalamus release?
Orexin.
What does orexin do?
Increases animals persistence in seeking food.
What Influences response to incentives and reinforcement in general?
Orexin.
What does the lateral hypothalamus control?
Insulin secretion and taste responsiveness.
What does stimulation of the lateral hypothalamus increase?
The drive to eat.
What does damage to the lateral hypothalamus do?
Causes aversion to food.
What does the ventromedial hypothalamus inhibit?
Feeding.
What does damage to the ventromedial hypothalamus cause?
Overeating and weight gain.
What is increased stomach motility?
The stomach empties faster than normal.
Why do birds sometimes stand on one leg?
To conserve heat.
How do toucans use their large beaks to regulate temperature?
During flight, blood flow through the beak is cooled, and the toucan tucks its beak under a wing to prevent heat loss.
Who introduced the term homeostasis?
Cannon.
What does homeostasis refer to?
Temperature regulation and other biological processes that keep body variables within a fixed range.
Define a set point.
A single value that the body works to maintain.
Explain negative feedback.
Processes that reduce discrepancies from the set point.
Explain allostasis.
The adaptive way in which the body anticipates needs depending on the situation, avoiding errors rather than just correcting them.
Give some examples of breakdown of homeostasis processes.
Obesity, anorexia nervosa, high blood pressure, and diabetes.
What is basal metabolism?
The energy used to maintain a constant body temperature while at rest.
How much energy does maintaining body temperature take?
Twice as much as all other activities combined.
How do we produce heat?
Metabolism in the brown adipose cells..
An animal ____ heat in proportion to its total mass, but it ____ heat in proportion to its surface area.
Generates, radiates.
Name some physiological mechanisms that increase body heat in a cold environment.
Shivering, decreased blood flow to the skin, and fluffing out the fur.