Chapter 9 - Quiz 4 Flashcards
8.1: Temperature Regulation: Homeostasis and Allostasis
Define homeostasis, use an example (2)
-biological processes that keep body variables within a fixed range
-example: temperature regulation is like a thermostat with a fixed temperature and when the house goes past that temperature either the A/C or furnace turn on
8.1 Temperature regulation: homeostasis and allostasis
Define set point
-a single value that a body works to maintain
-for example, the concentration of calcium in your blood
8.1 Temperature regulation: homeostasis and allostasis
Define negative feedback
-homeostatic processes that reduce discrepancies from the set point
-much of motivated behaviour can be described as negative feedback: something causes a disturbance and behavior proceeds until it relieves the disturbance
8.1 Temperature regulation: homeostasis and allostasis
Define allostasis and give an example (2)
-it describes the adaptive way the body anticipates needs depending on the situation, thus avoiding errors rather than correcting them
-example: our change in body temperature throughout the day
8.1 Temperature regulation: controlling body temperature
Define basal metabolism, by what is most of this produced? (2)
-energy used to maintain a constant body temperature while at rest
-largely through metabolism in brown adipose cells, they burn fuel like muscles cells but release it directly as heat
-most of our energy goes into our basal metabolism
8.1 Temperature regulation: controlling body temperature
Define ectothermic and give an example of an animal (2)
-they depend on external sources for body heat, they do not generate heat themselves
-amphibians, reptiles and most fish
-Poikilothermic
8.1 Temperature regulation: controlling body temperature
Define endothermic and define who is? (2)
-they can generate enough body heat to remain significantly above the temperature of the environment
-mammals and birds
-can usually keep core temperature constant
-small mammals radiate heat rapidly and need lots of fuel to keep their bodies warm because of their small surface area
8.1 Temperature regulation: controlling body temperature
What mechanisms do endothermic beings have for warm environments? How could a being do this? (2)
-to cool down, we have evaporation
-this looks like sweating, licking themselves or panting
8.1 Temperature regulation: controlling body temperature
How could an endothermic being warm up in a cold environment? (3)
-shivering
-decreased blood flow to the skin to prevent blood from cooling
-fluffing out fur to increase insulation (goosebumps)
8.1 Temperature regulation: the advantage of constant high body temperat
What is the primary advantage of maintaining a constant high body temperature?
-it keeps an animal ready for rapid, prolonged muscle activity even in cold weather
8.1 Temperature regulation: the advantage of constant high body temperat
Why did animals evolve a temperature of 37 C? Why not a different temperature?
-it is a trade off between the advantage of a high temperature for rapid movement and the disadvantage of high temperature for protein stability and energy expenditure
8.1 Controlling body temp: Brain mechanisms
Which areas of the brain is the primary area for controlling phsyiological mechanisms of temperature control? What physiological responses does it control? (2)
-the preoptic area/anterior hypothalamus or POA/AH
-controls sweating, shivering, changes in heart rate and metabolism and changes in blood flow to the skin
8.1 Controlling body temp: Brain mechanisms
What are the sources of input to the POA/AH?
-temperature in the skin, organs and hypothalamus, as well as prostagladins and histamines when someone is sick
8.1 Controlling body temp: Brain mechanisms
What would damage to the POA/AH result in?
-mammals can still regulate body temperature, but less efficiently
8.1 Controlling body temp: Fever
What does a fever mean for your set point in your body? How do we know it is an adaptation to fight illness based on other beings and based on humans? (3)
-it increases the set point
-animals and reptiles will use behavioural means (going somewhere warmer) to produce a fever when they’re sick
-as well, a moderate fever reduces bacterial growth and makes the immune system work more vigorously
9.2: Mechanisms of water regulation
What does your posterior pituatary release and what does it do? Why? (3)
-releases vasopressin AKA antidiuretic hormone
-raises blood pressure by constricting blood vessels causing you to decrease urination and increase thirst
-if you’re dehdyrated, this helps compensate for the decreased blood volume and allows the kidneys to reabsorb water from urine, making it more concentrated
9.2 Osmotic thirst
What are the two types of thirst?
-eating salty foods causes osmotic thirst and bleeding or sweating causes hypovolemic thirst
9.2 Osmotic thirst
Define osmotic pressure
-water will flow across a semipermeable membrane from the area of low solute concentration to high solute concentration
9.2 Osmotic thirst
How do certain neurons trigger thirst? Describe the process starting with eating something salty and define osmotic thirst (3)
-when you eat something salty, sodium ions spread through the blood and extracellular fluid but do not cross the membrane into cells
-this results in a higher concentration of solutes outside the cell than inside and the water flows out of the cells
-certain neurons detect their own loss of water and then trigger osmotic thirst, a drive for water that helps restore the normal state
9.2 Osmotic thirst
How does the brain detect osmotic pressure? Why in this area specifically? Name the structures involved (3)
-receptors around the third ventricle detect osmotic pressure and the sodium content of the blood
-this area specifically because the blood-brain barrier is weak here
-they are the OVLT (organum vasculosum laminae terminalis) and the subfornical organ SFO
-the OVLT also recieves input from receptors in the digestive tract, allowing it to anticipate osmotic need before the rest of the body
