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what is homeostasis
maintenance of a constant internal environment
why is temperature control important
maintain optimum temperature to ensure enzymes don’t denature, or membrane protein denature either
what is negative feedback
stimulus
change to environment
detects deviation from optimum
collects information and receptors
muscle or glands bring about change
what is thermoregulation
control of temperature, detected by thermoreceptors
when body temperature is too high
endotherms use internally generated heat to maintain body temperature
sweat glands release sweat, evaporates transferring heat energy from skin to environment
arterioles leading to skin capillaries dialate (widen) allowing more blood to flow through the skin
vasodilation
blood vessels in the skin dilate so more blood flows so more heat is lost to the environment
when body temperature is too low
skeletal muscles contract rapidly, require energy from respiration, released as heat
arterioles leading to skin capillaries narrow, less blood flow through the skin and conserve body temperature
vasoconstriction
blood vessel narrow, less heat energy is transferred to the environment
why do we get goosebumps
nerve impulse are sent to hair erector muscles contract, raise skin hairs and traps a layer of insulating air next to the skin
what are ecotherms
depend mainly on external heat sources and their body temperature changes with temperature of the environment, expose themselves to the sun
what is the purpose of negative ffedback
return conditions to optimum
what are examples of homestasis
thermoregulation
blood glucose control
blood pressure
osmoregulation
what are hormones
produced in glands and are secreted directly into the blood. Hormones are proteins
hormones are carried….
to the cells which they act upon, they are complementary to the specific hormone
process of second messenger model
adrenaline binds to transmembrane protein receptor on cell membrane of liver cell
binding of adrenaline causes inactive adenyl cyclase to change shape becoming active.
The enzyme catalyses ATP → cAMP
cAMP acts as second messenger which binds to inactive protein kinase, changing its shape (activate)
catalyses conversion of glycogen to glucose, moves out of liver by facilitated diffusion
what is glycogenisis
conversion of glucose into glycogen (creates glycogen)
what is glycogenolysis
breakdown of glycogen to glucose (breaks glycogen)
what is gluconeogenisis
production of glucose from sources other than carbohydrate (glyceryl and amino acids)
what does insulin respond to
changes in blood glucose concentrations
how does insulin lower glucose concentrations in blood
change in tertiary structure of glucose transport carrier proteins, be more open allowing more facilitated diffusion of glucose
increase number of carrier proteins responsible for glucose transportation
activation of enzymes that covert glucose to glycogen and fat
the blood glucose concentration is lowered by
increasing rate of absorption of glucose into cells
increasing respiratory rate of cells, increase uptake of glucose from the blood
increasing glycogenisis, rate of conversion of glucose to fat
what does glucagon do
attached to specific protein receptors on cell surface membrane of liver cells. Activating enzymes that convert glycogen to glucose, activating enzymes involved in glyconeogenisis
how is glucagon involved in gluconeogenisis
activates enzymes that convert glycerol/amino acids/ fatty acids into glucose
what does adrenaline do
attaches to protein receptors on cell surface membrane of target cell. It also activates enzymes that cause breakdown of glycogen to glucose in the liver
what is diabetes
metabolic disorder caused by an inability to control blood glucose concentrations due to lack of insulin/loss of responsiveness to insulin
symptoms of diabetes
going to the toilet a lot, especially at night
being really thirsty
tired
lossing weight
blurred vision
what is type 1 diabetes
body is unable to produce insulin as body attacks beta cells on islet of langerhans on pancreas. happens from childhood
how is type 1 diabetes managed
insulin injections
what is type 2 diabetes
glycoprotein receptors on cells being lost/less responsive to insulin. happens 40 and older
how is type 2 diabetes treated
regulating carbohydrate intake and exercise.
what are biosensors
monitor blood glucose concentrations
what is SMBG
self monitor blood glucose, prevents progression on microvascular (blindness, kidney failure and brain coordination) and macrovascular (coronary heart disease and stroke)