HOMEOSTASIS
HOMEOSTASIS
LO:Define homeostasis as the maintenance of a constant internal
environmentExplain that homeostasis is the control of internal
conditions within set limitsExplain the concept of control by
negative feedbackDescribe the control of the glucose concentration
of the blood by the liver and the roles of insulin and glucagon
from the pancreas
LO: Outline the symptoms and treatment of Type 1 diabetes
(detail of cells is not required)Name and identify on a diagram of
the skin: hairs, hair erector muscles, sweat glands, receptors,
sensory neurones, blood vessels and fatty tissueDescribe the
maintenance of a constant internal body temperature in humans in
terms of vasodilation and vasoconstriction of arterioles supplying
skin surface capillaries
LO: Define the term homeostasisHOMEOSTASISControl systems
responsible for keeping the internal conditions near constant=
maintenance of a constant internal environmentPhysiological factors
controlled:Core body temperatureMetabolic wastes (CO2 and
urea)Blood pHBlood glucose concentrationWater potential of the
bloodConcentration of the respiratory gases in blood
LO: Explain the concept of control by negative feedbackNEGATIVE
FEEDBACK
Negative feedbackAn increase in a factor results in something
happening that makes the factor decreaseA decrease in the factor
results in something happening that makes the factor increase
again
Homeostatic mechanism in mammals involves:Nervous system
information is in the form of electrical impulses and is
transmitted along neuronesEndocrine system uses chemical messengers
= hormones
LO: Explain the concept of control by negative feedback
LO: Describe the control of the glucose concentration of the
blood by the liver and the roles of insulin and glucagon from the
pancreasCONTROL OF THE GLUCOSE LEVELResponsible hormones: Insulin
and GlucagonInsulin: decreases the amount of glucose in blood
stream by binding to the cell receptors making them absorb and
store glucose in the liver or muscle cellsGlucagon: increases the
amount of glucose in the blood stream by breaking down the complex
carbohydrates in liver and muscle cells and releasing glucose into
the blood stream
LO: Outline the symptoms and treatment of Type 1 diabetes
DIABETES TYPE 1
Beta cells of pancreas are destroyed by white blood cells =
autoimmune disease .Beta cells are responsible for the production
of hormone InsulinResult: your body breaks down fats and proteins
in order to get energySymptoms - hyperglycemia:Excessive
hungerExcessive thirstFrequent urinationUnexplained weight
lossFatigueWeaknessIrritabilityBlurry vision
LO: Outline the symptoms and treatment of Type 1 diabetes A day
in the life with type 1 diabetes
LO: Describe the maintenance of a constant internal body
temperature in humansMAINTAINING CONSTANT BODY TEMPERATURE=
ThermoregulationInvolves both nervous and endocrine systemsMammals
are not dependent on absorbing heat from the surrounding have
mechanisms that control retention of body heat and heat lossHeat is
produced during respiration much of it by liver cells it is then
absorbed by blood and distributed around the body
The control of body temperatureCentre of the control =
hypothalamusReceives a constant input of sensory information about
the temperature on the blood and about the temperature of the
surroundingsContains thermoreceptor cells Core temperature =
temperature inside the body; approximately 37C (it fluctuates a
little)
LO: Name and identify on a diagram of the skin: hairs, hair
erector muscles, sweat glands, receptors, sensory neurones, blood
vessels and fatty tissue
LO: Describe the maintenance of a constant internal body
temperature in humans Physiological responses in
coldVasoconstriction = muscles in the wall of arterioles that
supply blood to capillaries near the skin surface contract; lumen
is narrowed and the supply of blood reduced = less heat is lost
from the bloodShivering = the involuntary contraction of skeletal
muscles generates heat which is absorbed by the blood and carried
around the bodyRaising body hairs = muscles and the base of hairs
contract to increase the depth of fur to trap the air close to
skin
Physiological responses in coldDecreasing the production of
sweat = reduction of the loss of heat by evaporationIncreasing the
secretion of adrenaline = increases the rate of heat production in
the liver
LO: Describe the maintenance of a constant internal body
temperature in humans Physiological responses in heatVasodilation
the muscles in arterioles in the skin relax and allow more blood to
flow through the capillaries = more heat is lostLowering body hairs
hair erectors relax reducing the depth of fur Increasing sweat
production sweat glands increase the production of sweat which
evaporates on the surface of the skin = heat is removed
