bio paper 2- homeostasis and response

what is the function of the nervous system

enables organisms to react to their surroundings and coordinates behaviour

two parts of the CNS

brain and spinal cord

What is homeostasis?

Homeostasis is the regulation of internal conditions of a cell or organism.

why are reflex actions rapid

they do not involve the conscious part of the brain

stimulus, receptor, coordinator, effector, respons

the pathway of a nervous response

reflex arcs

sensory receptor, sensory neuron, relay neuron, motor nueron

dendrites

branched endings of neurons, makes connection with other neurons.

myelin sheath

insulates the axon, increasing impulse speed.

axon terminals

transmit messages.

synapses

gaps between neurons allowing electrical impulses to cross between neurons.

cerebral cortex

outer layer of the brain, playing a role in consciousness,

medulla oblongata

above the spinal cord, controls breathing and heart rate.

cerebellum

back of the brain, coordinates muscle activity.

3 actions in homeostasis

body temp, blood glucose and water levels.

accomodation

changing the shape of the lens to foccus

myopia

short sightedness

hyperopia

long sightedness

vasodilation

blood vessels dilate, sweat is produced.

vasoconstriction

blood vessels constrict, shivering

cornea

focuses light by bending it

retina

receptors containing rods and cones

iris

contains muscles that contract and relax

near object

ciliary muscles contract

suspensory ligaments slack

lens is thicker

distant objects

ciliary muscles relax

suspensory ligaments tighten

lens is thinner

short sighted use what lens

concave lens

long sighted use what lens

convex lens

endocrine system

system of glands that secrete hormones into the bloodstream

where is the pituitary gland

in the brain

insulin and glucagon

which hormones interact to regulate blood glucose levels

function of the kidneys

to produce urine excreting water, ions and urea

how does the endocrine system work?

blood carries hormones to the targeted organ where an effect is produced.

after insulin is released

glucose moves into cells

after glucagon is released

glycogen is converted to glucose

water level in blood is controlled by the hormone

ADH

type 1 diabetes

early onset

pancreas stopped producing insulin

insulin injections

type 2 diabetes

later onset

body dosen’t respond to insulin

treated with exercise and diet

negative feedback systems

work to maintain a steady state and slow a reaction

adrenaline

produced by adrenal glands

boosts delivery of oxygen

does not involve negative feedback

thyroxine

produced by thyroid gland

regulates how quickly body uses energy

controlled by negative feedback

thyroid gland where

front of the neck

step 1 dialisis

blood removed from patients body

dialysis step 2

filtered through dialysis machine

dialysis step 3

patients blood passes over dialysis fluid

dialysis step 4

dialysis fluid has no urea

dialysis step 5

urea and waste products diffuse from high concentration in patients blood to low concentration in dialysis fluid.

what is is called when an egg is released every 28 days

ovulation

FSH

causes an egg to mature in the ovary

LH

causes the egg to be released

oestrogen and progesterone

maintain uterus lining

stage 1 period

FSH is released by the pituitary gland, going down to the ovaries and causing the egg to mature.

stage 2 period

FSH causes the ovaries to produce oestrogen

stage 3 period

oestrogen causes the lining of the uterus to become thick and stops more FSH from being released

stage 4 period

pituitary gland starts releasing LH

stage 5 period

LH triggers ovulation, egg is released.

stage 6 period

ovary starts producing progesterone, stops FSH and LH production, and building up the lining of the uterus.

testosterone

produced by the testes, stimulates sperm production

IVF treatment

an egg is removed from the woman's ovaries and fertilised with sperm in a laboratory. The fertilised egg, called an embryo, is then returned to the woman's womb to grow and develop.

plant hormones

plants produce hormones to coordinate and their response to light and gravity.

phototropism

the orientation and growth of plants in response to light.

geotropism

the growth of plants in response to gravity.

auxins

plant growth regulator, unequal distribution of auxin cause unequal growth rates.

agricultural uses of auxins

weed killer

rooting powder

ethane

acts as a hormone to control cell division

agricultural uses for ethane

control ripening of fruit

barrier contraception

condoms- prevent sperm from reaching egg

how are amino acids excreted from the body

form ammonia in the liver which is converted to urea and excreted.

how is kidney failure treated

dialysis or organ transplant

oral contraceptives, injection or skin patch.

hormonal contraception.

eye adaptation to dim light

the pupil reflex increases the diameter of the pupil. This increase the amount of light that enters the eye.

thermoregulatory system

contains receptors sensitive to the temperature of the blood.

if blood glucose is too low

the pancreas produces glucagon that causes glycogen to be converted into glucose and relased into the blood.

what is sweat

water, ions and urea.

if body cells gain or lose too much water by osmosis

they do not function efficiently.

ADH is released by the pituitary gland

it causes the kidney tubules to become more permeable which allows fluids or gases to pass through it

gibberellins

important in initiating seed germination.