Chapter 7 Hormones and Co-ordination Flashcards
what does the nervous system and hormones do
they enable the body to respond to external changes and to control the internal environment
why does blood play a central role in homeostasis
it transports materials and distributes heat
what are reflex actions
they are rapid automatic responses to stimuli
how does a voluntary action start
it starts from impulses from the brain
what is the brain a centre for
the brain is a centre for co-ordination with the ability to learn and remember
what are the benefits of reflex actions
moving a hand away from a heat source, pupil constricting in bright light
what is the difference between reflex actions and voluntary actions
voluntary actions is where your brain thinks about what you want to do, whereas reflex reactions happen automatically to protect the body from danger
analyse a reflex action
stimulus - sensory neurone - CNS - motor neurone - effector - response
what is a synapse
tiny gaps between the neurones where the electrical impulse stimulates the production of a chemical which diffuses across the gap
what is the role of the cornea
transparent and bens light rays towards the lens
lens
can change shape to focus light on to the retina
ciliary muscles
changes the thickness of the lens when focusing
suspensory ligaments
holds the lens in place
iris
changes size of pupil to control the amount of light entering the eye
how is long sight corrected
converging
how is short sight corrected
diverging
what is a optometrists
they are scientists who evaluate the ability of the eye to detect light, they can also detect other health problems by observing changes in the eye and testing pressures in the eye
type of light in the workplace
reduce accidents, increase productivity
blue enriched light improves alertness and mood
but too much light can damage eyes
what are the benefits of corneal transplant
it replaces the damaged layer of cells therefore light can pass onto the retina
how do you recongnise reinopathy
this is when blood vessels in the retina are damaged, this is the result of high blood sugar with someone of diabetes and pressure
they can test this by puffing air into the eye to help diagnose this
how do you recongnise alzhimers
you can identify a protein in the eye which is usually found in the brian
what is the range of frequency audible of the human ear
20-20000 hz
what are hormones
hormones are chemicals released by ductless glands into the blood which may affect a target organ or the whole body
what is the role of the growth hormone
stimulates growth and cell reproduction
what is the role of the thyroxin
controls the metabolic rate
what is the role of insulin
causes the liver to absorb glucose and covert is to glycogen when blood sugar levels are high
what is the role glucagon
causes the liver to change glycogen to glucose when blood sugar levels are low
what is the role of adrenaline
increases blood sugar heart rate and breathing rate
what is the role of oestrogen
controls female sexual development
what is the role of testosterone
controls development of male sexual characteristics
what are endocrinologists
these are scientists who investigate the effect of hormones on the body functioning
what are the endocrine glands stimulated by
chemical changes in the blood
describe how ADH works
ADH increases the reabsorption of water by the kidneys when the hypothalamus detects that the blood water content is too low
how is blood sugar detected
beta cells in the islets have receptors to detect high concentrations of glucose - then insulin is released by the islet cells, when there is a fall in glucose concentration then the beta cells are no longer stimulated and they stop producing insulin.
alpha cells in the islet result in glucoagon secretion ….
what are the advantages of adrenalin during times of stress
more oxygen and glucose reaches muscles for aerobic respiration
therefore more energy released
the methods of banting and best
they extracted insulin
Banting realised that digestive juices in the pancreas destroying the hormone
they decided to tie off the pancreatic duct in healthy dogs, this meant that the cells producing the digestive juices died and the cells that were left the Islet were removed and extracted in to diabetic dogs which healed the dogs
the modern methods of treating diabetes
type 1 - pancreas stops producing inuslin, treated with a healthy diet and insulin injections
type 2 - develops gradually and the pancreas does not produce enough insulin or the liver and other cells become too insulin resistant - weight control, diet and physical activity, then injections
why cant insulin be given in tablet form
because its a protein and would be digested
how is body temperature monitored and controlled
by the thermoregulatory centre in the brain which sends nerve impulses to the organs which need to act
how does the thermoregulatory centre measure temperature
measures the temperature of blood flowing through the brain
and measures the skin temperature - skin receptors
what does sweating do
sweating cools the body, more water is lost when it is hot and has to be consumed
if sweating increases
loss of water in urine decreases
where is the thermoregulatory centre
it is in the hypothalamus
