nervous system & hormones

central nervous system

the brain and spinal cord form together to make the central nervous system that controls and co-ordinates the responses between the receptors, effectors and muscles

what is anything we respond to called

central nervous system stimulus

stimulus- receptor- effector- response

coordination

the receptors and effectors are linked by a coordinator. neurone’s then link the receptors and effectors to the coordinator. the neurone carries info as small as electrical charges called nerve impulses

5 parts of coordination

stimulus- receptor- brain- effector- response

what are receptors grouped together called

complex sense organs

examples

smell, sound and sight

behaviour

our responses to the environment

voluntary action

an action that we deliberately choose to do and they involve conscious thought

reflex actions

an action that doesn’t involve conscious thought, meaning they are reflex

reflex action example

if you accidentally touch a very hot object you respond immediately by rapidly withdrawing your hand, meaning that you move your hand before it can get badly burned. this action does not involve any thinking time

2 main characteristics of reflex actions

• they occur rapidly

• they do not involve conscious control( thinking time)

what makes reflex actions so rapid

in the reflex pathway the total length of the pathway is kept as short as it possibly can be, with the minimum number of neurones involved. there are few gaps between the neurones( synapses) as they are the places where the nerve impulses travel relatively slow

reflex arc

receptor, sensory, association , motor, effector

association neurone

joins sensory and motor neurones

sensory neurone

carries information from the receptors to the spinal cord

motor neurone

carries info from the spinal cord back to muscle effector , causing a response

whats another type of communication system

hormones

hormones

they are chemical messages produced by special glands which release them into the blood.

target organs

hormones can only affect certain organs

what do hormones act like

they act slower than the nervous system and over a longer period

what is the hormones role

they maintain the internal environment out of the body in a relatively constant state in response to changes inside and outside the body. this is referred to as homeostasis

whats an example of homeostatic role of hormones

they control the concentration of glucose in the blood by the hormone insulin and controlling the water content of the body, referred to as osmoregulation

insulin

a hormone that prevents the concentration is of glucose in the blood from becoming too high

why is glucose needed

it is constantly needed by all cells for respiration and therefore must always be present at a sufficient concentration.

what happens if theres too much glucose in the blood

it can damage body cells due to water loss by osmosis

where is insulin found

insulin is produced and released into the blood by special cells in the pancreas responding to increasing or high blood glucose concentration

when is insulin produced and released

this usually occurs after a meal, especially if the meal is rich in carbohydrates

what is the main target organ for insulin

the liver

what does it cause

• increased absorption of glucose from the blood, so reducing glucose concentration

• the conversion of excess glucose into glycogen, which is stored in the liver and to a lesser extent in muscle cells

• increased respiration

5 stages of how insulin controls the blood glucose concentration

• normal blood glucose concentration

• meal rich in carbohydrates

• rise in blood glucose concentration

• pancreas produces insulin

• fall in blood glucose concentration( absorbed mostly by liver converted to glycogen and respired)

the effect of insulin on blood sugar concentration

when blood concentration is low, less insulin is produced. this means that the above processes do not take place or take place at a slower rate, helping to raise the concentration of glucose in the blood

diabetes

when blood glucose regulation fails

diabetes explained

diabetes is a fairly common condition in which the body doesn’t produce enough insulin to keep the blood glucose at a normal concentration. individuals who develop diabetes are unable to control the concentration of their blood glucose without treatment

symptoms of diabetes

• frequent urination due to glucose in the urine

• often thirsty

• lethargy

type 1 diabetes

usually develops in childhood, and is when the pancreas cant produce enough insulin

type 1 treatment

it is usually treated by injection of insulin and by a carefully controlled diet where the intake of carbohydrates is carefully monitored

why can it be hard for type 1 diabetes to be controlled

problems may arise if too much insulin in injected or not enough food is eaten at regular intervals

what happens if the blood sugar drops too low

a hypoglycaemic attack may occur and unconsciousness as a result

what if the blood sugar concentration remains too high for a long period of time

serious medical complications can result

type 2 diabetes

usually occurs in older people, but becoming increasingly common in young people due to obesity

what happens to the insulin in type 2