chapter 5 homestasis

what is homeostasis

process of keeping the environment inside the body fairly constant, these mechanisms help us to become independant of our external environment

what aspects of the internal environment that the body needs to regulate

core body tempuarture

pH and dissolved substance concentration in body fluid

what is a feedback system

circular situation in which the body response to stimuli, can be positive or negative depending on if it decreases or increases the stimuli

common features in feedback systems

stimuli>receptor>modulator (control centre responsible for processing info from receptor and sends to effector)>effector

what are steady state feedback systems and example

negative feedback system. body temp, hot, sweat, then not so hot

positive feedback system example

oxytocin stimulating contractions which produces more oxytocin which stimulates more contractions during the release of baby

what is thermoregulation

regulation of body temperature that makes us relalitively independant of environmental temperature

whats the ideal body temperature of people

37 C

how does the body produce HEAT

carbs, protiens and lipids that we eat contain chemical bonds, when energy released the food is oxidised during cellular respiration. most energy from this is released as heat, rate of release of this energy is metabolic rate

exercise and stress and fever can effect this. when body increases by 1 C rate of biochemical reactions increase by 10%

how does the body regulate tempurature using temp receptor

thermoreceptors, those in skin and mucsos membrane are called peripheral thermoreceptors, those located in hypothalamus azre called central thermoreceptors, cold receptors detected lower than average, heat receptors detect higher than adverage

how does the skin regulatre temperature

large SA, means it can speed up and slow down rate at which heat is released

conduction; transfer of heat between particles
convection: transfer of heat by the movement of liquid or a gas ( such as moving air)
radiation: transfer of heat by infared radiation being emitted by objects
evaporation: liquid to gas, absorbing heat

how does blood vessels effect heatloss

diameter of these aterioles is controlled by automatic nerves, if diameter increased via vasodialation, more blood is transported to the capillaries in the skin and heat loss increasing. if diameter decreased via vasoconttriction, less blood is transported to capillaries in skin thus heat loss decreases.

how does sweating effect heatloss

sweating is active secretion of fluid by the sweat glands and periodic contraction of cells surrounding ducts to pump to sweat to the skins surface, sweat contains dissolve substance,, cooling of skin results in cooling of blood flow through the skin

how does shivering effect heat loss

due to increase in skeletal muscle tone, muscle temours that occure at a rate between 10-20 per second

what occures in extreme cold - hypothermia

the hypothalamus sends an impulse to the adrenal medulla stimulating the release of adrenaline and noradrenaline. These hormones increase metabolic rate to prepare the body for fight or flight and in turn increase heat production

when living in cold conditions from an extended peri0od of time: , the body responds by increasing the production and release of thyroxine. Thyroxine also increases metabolic rate and hence increases heat production

how does the body prevent body temp from falling

• impulses from hypothalamus which stimulates sympathetic nerves that causes arterioles in skin to constrict - vasoconstriction

• a second response initiated by hypothalamus - stimulation of adrenal meddulla by sympathetic nerves secreting adrenaline and nonadrenaline which increases metabolism so there is an increase heat production

• shivering under the primary control of the hypothalamus with the consious part in cerebal cotrex to supress it

• production of thyroxine, hypothalamus secretes TSH, to stimulate thyroid gland, which increase metabolic rate

• behavioural like putting on a jumper

how does the body prevent body temp from rising

• vasodilation of skin arteriols

• when evironenmetn above 28 C sweating occures

• decreased production of thyroxine

• behavourial responses like taking of jumper

what is a heat stroke

body temperature rises and regulatory mechanisms cease, anything over 42 C is dangerous, 45 C being death

what is heat exausghstion

extreme sweating and vasodilation to lose heat, loss of water in sweating deduces the volume of plasma and vasodialation redcuces resistance to blood flow

what is hypothermia

metabolism rate is so low that heat production is unable to replace the heat lost, death can occure at temperatures below 32 C

what is the role of the liver

control of blood sugar concentration, able to convert glucose into glycogen for storage or glycogen to glucose for release into blood

whatt does the heptic portal vien do

carries glucose to the liver

when in the liver what does glucose do

be removed by blood to provide energy for liver

removed by liver or muscle and converted into glycogen for storage

continue to circulate in blood for body cells to absorb for energy

converted into fat for long-term storage

glycogenises

glucose to glycogen molecules

glycogenolysis

glycogen to glucose

what does alpha cells secrete in the pancreus

glucogen

what do beta cells secrete in the pancreus

insulin

how does beta cells cause decrease in in blood glucose levels

accelerating transport of glucose from the blood into body cells

accelerating conversion of glucose into glycogen in the liver and skeletal muscles

stimulating conversion of glucose to protiens

stimulating converstion of glucose to fat (lipogenesis)

how does glucogen from alpha cells cause an increase in blood glucose levels?

stimulating glycogenolysis - glycogen into glucose

stimulating glyconeogenisis, the production of new sugar molecules from fats and amino acids, in the liver

mild stimulating effects of protien break down

what does the adrenal gland consists of

just above the kidney, the outer part is the cortex and the inner is called the medulla

what is hyperglycemia

when you have insufficent insulin that may be because increaase food or alchol, it happens gradually, the symptoms include thirst, blurred vision, fatigue, hunger and coma in worse
you can be given insulin as a cure

hypoglycemia

excessive exerisise, too much medication and lack of food may cause this, this happens suddely and may lead to fatigue, anxiety, hunger, sweats

check blood glucose levels and give orange juice