CHAPTER 10 Flashcards
what is homeostasis
the regulation of internal conditions for cells in response to internal and external changes to maintain the best functioning environment
why are enzymes so important
they control the functioning of the cell
examples of internal conditions controlled by homeostasis 3
blood glucose levels
temperature
water content
examples of internal changes 3
when you get hotter after exercise
your blood glucose levels go up after eating
when you lose water in hot weather
what are receptors
cells that detect changes in internal or external environment
what are coordination centres and what they do
areas that receive and process information from receptors
they send out signals to other parts of the body to react
what is an effector
something that reacts to the changes to restore optimum conditions
what does the nervous system do
sends electrical impulses around the body so you can react to your surroundings
how are electrical signals transported
neurones
pathway that an impulse takes
receptor sensory neurone relay neurone motor neurone effector
difference between a neurone and nerve
a nerve is a group of neurones
what is the CNS and what does it involve
the central nervous system, made of brain and spinal cord
what is a reflex
an automatic response
examples of a reflex 2
touching something hot and moving away
something coming at your face and you the move
why are reflexes so important
help keep us safe, they happen so fast
what are the three neurones involved in a reflex arc
sensory neurone
motor neurone
relay neurone
what do sensory neurones do
carry impulses from organ to CNS
what do motor neurones do
carry information from CNS to body
what do relay neurones do
connect sensory neurone and motor neurone found in CNS
describe a reflex arc
the impulse travels from receptor to sensory neurone to relay neurone in CNS to motor neurone and back to effector
what is important to remember about reflex arc
doesn’t need brains input
what is a synapse
something connecting the neurones which the impulse must travel across
what happens at the synapse
the electrical impulse cant cross so releases a chemical that can and this starts a new electrical impulse at the next neurone
why is it important reflexes don’t go to conscious area of brain
would take too long to process
what does the cerebral cortex do
consciousness
intelligence, memory and language
what does the cerebellum do
muscle activity and balance
what does the medulla do
unconscious activities like breathing, heart rate and gut movement
what does the hypothalamus do
regulates temperature
what does the pituitary gland do
secretes hormones for other purposes
how can scientists find out about the brain 3
studying people with brain damage
electrical stimulation
MRI scans
how does studying people with brain damage help scientists learn about the brain
they can match changes in behaviour with affected areas of the brain
what is the importance of the brain
controls everything
processes information
sends out necessary signals for responses
how can electrically stimulating the brain help scientists
they can see what effect stimulating different has
how can MRI scans help scientists
it shows what area of the brain is effected by a certain problem
eg a tumour so they can see what effect this has on the body, for example if a person cant walk
problems with the brain
very easily damaged and destroyed
easy to cause unintended damage in surgery
difficult to treat conditions cant reach with drugs
function of sclera
though so eye is not easily damaged
function of cornea
lets light into the eye
function of iris
controls size of pupil
function of suspensory ligaments and ciliary
change shape on lens
function of lens
focusses light rays on retina
function of retina
sends impulses to brain along optic nerve
how is light focussed on the retina
refraction
what is accommodation
changing the shape of the lens so you can se clearly
what are the light rays from a near object like
very spread out
what are the light rays from a distant object like
flat almost parallel
how does your eye change to see distant objects
ciliary muscles relax
suspensory ligaments pulled tight
lens flat and thin
small refraction
how does your eye change to see near objects
ciliary muscles pulled tight
suspensory ligaments relax
lens fat and thick
large refraction
what is myopia
short sightedness
what is hyperopia
long sightedness
what is short-sightedness / myopia
when near objects are clear but distant ones are blurry
what is long-sightedness / hyperopia
distant objects are clear but near ones are blurry
why does myopia happen
the light rays are focusses infant of the retina so the image there is blurry
how to correct myopia
concave lens ;
spreads out light rays so lens can focus them correctly onto retina
why does hyperopia happen
light is focussed behind retina
how to correct hyperopia
convex lens ; brings light rays closer together so lens perfectly focuses on retina
how is laser eye surgery used to correct myopia
makes lens thinner so refraction is weaker
how can laser eye surgery correct hyperopia
changes shape of lens so refraction is stronger
what is ADH and what does it do
hormone released from brain to tell kidneys how much water to retain
where is ADH released from
pituitary gland
where is insulin produced
pancreas
where is insulin stored
liver
what part of the eye controls how much light gets through
iris
what are the chemicals used to cross the synapse
neurotransmitters
what happens when adrenaline is released
stimulates (increased glucose, increased heart rate, increased breathing rate) for increased respiration for more energy to run
