7120 Lecture Notes - Lecture 8: Allostasis, Posterior Pituitary, Semipermeable Membrane
21 Jun 2018
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LECTURE 8 – INTERNAL REGULATION and EMOTIONAL BEHAVIOURS (CH 9 and 11)
Internal regulation
Temperature Regulation
- Temperature affects many aspects of behaviour
oEg activity levels, sleep wake cycles
- Temp regulation is vital to the normal functioning of many behavioural processes
Homeostasis and Allostasis
- Homeostasis: maintenance of a set point
- Set point: a single value that the body works to maintain
oEg levels of water, oxygen glucose, calcium, protein, fat and acidity in the body
- Allostasis: the adaptive way in which the body anticipates needs depending on the situation
oIe pre loading for exercise, supplements, fluids etc to help
Controlling body temperature – poikilothermic
- (ectothermic) : idea that the body temperature matches that of the environment
oThe organism lacks the internal, physiological mechanisms of temperature
regulation
oTemperature regulation is accomplished via choosing locations in the environment
oAlthough known as ‘cold-blooded’, organism is only cold if environment is cold
oFish, reptiles – mainly
oSome sharks and tuna are able to regulate temp; need for more food
Controlling body temperature – Homeothermic
- (endothermic): use of internal physiological mechanisms to maintain an almost constant
body temperature
oRequires energy and fuel
oSweating and panting decrease temperature
oIncreasing temperature is accomplished via shivering, dec blood flow to the skin, and
fluffing out fur to increase insulation
Constant high body temperature
- Mammals evolved to have a constant temp of 37 degrees
- Muscle activity benefits from being as warm as possible
- Maintaining a higher body temp increases energy demand
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- Proteins in the body break their bonds and lose their useful properties at higher
temperature
- SA/V ratio dependent on food intake
Brain mechanisms – POA/AH
- Temperature regulation is predominantly dependent upon areas in the preoptic are/anterior
hypothalamus (POA/AH)
oControls panting, sweating, shivering
- POA/AH receives input from
oTemp receptors throughout the body
oImmune system
Integration of temperature information by the POA/AH
-
oDamage – act as like ectotherms
Mechanisms of water regulation
- Human mechanisms of water regulation vary depending on circumstance
- Can be conserved by
oExcreting concentrated urine
oDecreasing sweat
- Most often, water regulation is accomplished by drinking more water than we need and
excreting the rest
Vasopressin
- A hormone released by the posterior pituitary
oRaises blood pressure by constricting vessels
oCompensates for dec water volume
oKnown as a ADH
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oEnable kidneys to reabsorb water and excrete highly concentrated urine
Thirst
- Two different kinds
oOsmotic thirst: result from eating salty foods
Solutes inside and outside a cell create osmotic pressure
Water flows across a semi-permeable membrane from low conc to
high conc
Osmotic pressure occurs when solutes are more conc on one side
oAbove normal conc of 0.15M
Detecting osmotic pressure
Brain detects osmotic pressure from
oReceptors around the third ventricle
oThe OVLT (organum vasculosum laminae terminalis) and the
subfornical organ
Detect osmotic pressure and sodium content of the
blood
oReceptors in the periphery, including the stomach and
digestive tract
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find more resources at oneclass.com
Document Summary
Lecture 8 internal regulation and emotional behaviours (ch 9 and 11) Temperature affects many aspects of behaviour: eg activity levels, sleep wake cycles. Temp regulation is vital to the normal functioning of many behavioural processes. Set point: a single value that the body works to maintain: eg levels of water, oxygen glucose, calcium, protein, fat and acidity in the body. Allostasis: the adaptive way in which the body anticipates needs depending on the situation: ie pre loading for exercise, supplements, fluids etc to help. Mammals evolved to have a constant temp of 37 degrees. Muscle activity benefits from being as warm as possible. Maintaining a higher body temp increases energy demand. Proteins in the body break their bonds and lose their useful properties at higher temperature. Temperature regulation is predominantly dependent upon areas in the preoptic are/anterior hypothalamus (poa/ah: controls panting, sweating, shivering. Poa/ah receives input from: temp receptors throughout the body, immune system.
