Homeostasis- regulation of the bodys internal environment Flashcards
what is the homeostatic mechanism
external environment changes largely over time, internal environment has small changes over time
homeostasis regulates
a physiological variable relative to a set point or a set range
what things may homeostasis involve to maintain itself
-negative feedback
-positive feedback
-feedforward
in most complex regulation, all three may be used
what is negative feed back
-body temperature regulation in endothermic animals
-endotherm vs ectotherm
-homeotherm vs heterotherm
-hermogenesis
how do endotherms generate heat
internally
birds and mammals—keep their bodies at an optimal temperature by regulating two processes: (1) the amount of heat generated by internal oxidative reactions and (2) the amount of heat exchanged with the environment.
how do ectotherms generate heat
ectotherms fluctuate with environmental temperatures, and ectotherms are typically less active when it is cold.
what are homotherms
maintain body temperature at a set range
what are heterotherms
varies their body temp depending on what external environment is doing
what is thermogenesis
The generation of heat by oxidative mechanisms in nonmuscle tissue throughout the body is termed non-shivering thermogenesis. In the young of many mammals, the most intense heat generation is by nonshivering thermogenesis that takes place in a specialized brown adipose tissue (also called brown fat), which can produce heat rapidly.
what are the two ways hypothalamic centres can be triggered
-change in skin temp which triggers peripheral thermoreceptors in the skin
-change in core temperature which triggers central thermoreceptors in hypothalamus, abdomen organs, and elsewhere
what is the hypothalamic centre
-its for the thermalregulation (bodys thermostat)
-organ to make comparison
how much change can the hypothalamic centre sense
0.01 deg Celsius cange in temp
what are some things the the sympathetic nervous system can do to regulate body temp
-smooth muscle in arteriole in skin (vasodilation and constriction, adjustments in the loss or conservation of heat in the skin)
-sweat glands (sweating, adjustment in heat loss)
-smooth muscle in the skin (piloerection, adjustment in conservation or loss of heat)
what are some things that the motor neurons can do to regulate body temp
-skeletal muscles (muscle tone, shivering, adjustments in muscle activity (in metabolic output))
what is negative feed back
returns variable to set point
i.e minimizes difference between actual level and set point
what is positive feed back
moves variable away from set point
i.e amplifies difference between actual level and the set point
what are positive feed back cycles used for
used to quickly increase or decrease a process
how are the apmication effects of positive feed back shut off
they are eventually turned off by negative feed back
what is feed forward
future needs are anticipated and physiology is adjusted in advance
explain the negative feed back of the thyroid
-hupothalamaus releases TRH
-that stimulates anterior pituitary gland which releases TSH
-this stimulates the thyroid which produces T3 and T4
-too much produced signals to hypothalamus slows the process and not enough signals to speed it up
explain the negative feedback of the endocrine
-homeostasis normal levels of Ca2+
-Ca2+ exceeds normal level
-parathyroid glands are inhibited by Ca2+
-less PTH is secreted
-less Ca2+ is released from bone into blood, reintroducing blood Ca2+ level
-homeostasis normal levels of Ca2+
-Ca2+ level in blood falls below normal limit
-parathyroid glands are stimulated by low Ca2+ level
-more PTH is secreted
-PTH stimulates release of Ca2+ from bone into blood, rising blood Ca2+ level
explain the positive feed back of child birth
-pituitary gland triggers release in hormones which enters blood
-this increases the strength of uterine contractions
-the strong contractions stimulate the brain to make even more hormones
what is goiter
disruption to the negative feed back with low iodine levels in the thyroid
