homeostasis

What is homeostasis

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes

What does homeostasis control

Body temperature

Water levels

Blood glucose concentration

What do receptors do

detect stimulus

What are the coordination centres

Spinal cord

Brain

Pancreas

What are the two effectors

Muscles

Glands

What are reflexes

Automatic and unconscious

Explain how the reacts to stimulus

Stimulus detected by receptors

Electrical impulse travels along the sensory neurone

In the CNS the electrical impulse travels along the relay neurons

Chemicals diffuse across the synapse

Then electrical impulse travels through the motor neurone

The impulse reaches an effector and gives out response

What are synapses

Gaps between two neurons

How can you test reaction time

Ruler drop test

What is the brain

Made up of interconnected neurons, which controls complex behaviour

Why is it hard to explore the brain

Complex and delicate

Easily damaged

Drugs given can’t always reach brain because of membrane

Not fully understood which part of the brain does what

What does the cerebral cortex do

Control consciousness, intelligence, memory and language

Where is the cerebral cortex located

Outer part of brain

What does The cerebellum do

Controls movement of muscles

Where is the cerebellum located

Back of brain

What does the medulla do

Controls unconscious behaviours like breathing and heart rate

Where is the medulla located

Brain stem

How can you study regions of brain

Patients with brain damage

Electrically stimulating

Using MRI

What is accommodation

Changing shape of lens to Focus of near or distant object

function of retina

Defect light and send signals to brain through optic nerve

function of optic nerve

Carries electrical impulse from retina to brain to create an image

Function of sclera

White outer layer protects eye

Function of cornea

Allows light through and refracts light onto retina

Function of iris

Contract or relax size of pupil

What happens to the eye in bright places

circular muscles contract and radial muscles relax to make pupil smaller

What happens to eye in dim light

Circular muscles relax and radial muscles contract to make pupil larger

Function of ciliary muscles and suspensory ligaments

Hold lens in place and control shape

What happens when focusing on near object

Ciliary muscles contract

Suspensory ligaments loosen

Lens is thicker and more curved

Light refracts more

What happens when focusing on distant object

Ciliary muscles relax

Suspensory ligaments tighten

Lens is thinner and less curved

Light refracts less

What is the word for shortsightedness

Myopia

What is the word for longsightedness

Hyperopia

How can eye defects be treated

Spectacle lenses

Contact lenses

Laser eye surgery

Replacements lens

what lens is used to treat myopia

Concave

What lens used to treat hyperopia

Convex

What part of the body monitor ls body temperature in the brain

Thermoregulatory centre

What happens when body temp is too high

Sweat

Vasodilation : more blood flow closer to surface of skin, increase energy transfer from body

What happens when body temp is too low

Sweating stops

Skeletal muscles contract (shivering)

Hairs stand on end to create insulating layer to trap warm air

Vasoconstriction: less blood flow to surface of skin, less thermal energy loss

What is the nervous system

The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body

What is the endocrine system

Sends hormones around to body to produce a response

What are hormones

Chemical messengers

What is also knows as the master gland

Pituitary gland

Function of pituitary gland

secretes hormones into blood to have an effect on the body or acts on other glands to stimulate them to produce different hormones

Function of pancreas

Secretes insulin

Controls blood glucose levels

function of insulin

Reduces blood glucose concentration

By binding on cells in target organs causing glucose to move from blood into muscle cells for respiration

Function of thyroid

Controls basal metabolic rate, heart rate and temperature

Secretes thyroxine (controls the basal metabolic rates)

Function of adrenal gland

Secretes adrenaline

Fight or flight response

Function of ovary

Secretes oestrogen

Development of female secondary sexual characteristics

Function of testes

Production of sperm

Male secondary sexual characteristics

Difference between nervous system and hormonal System

Hormonal is Much more slower

What is excess glucose converted to and where is it stored

Glycogen

In liver

What happens when glucose level decrease

Pancreas produce Hormone glucagon

Glucagon binds to liver cells causing glycogen to be broken down into glucose

Glucose is released into blood increasing blood glucose concentration

What is the negative feedback for blood glucose level

If level is too high, pancreas produces insulin to reduce blood glucose level

If it’s too lovely, glycogen increases the glucose level

What is type 1 diabetes

Can’t control blood glucose levels

What is type 2 diabetes

Doesn’t respond to insulin

What happens in type 1 diabetes

blood glucose level can rise to a fatal amount

Glucose is excreted with urine and lots of urine is produced leaving the individual thirsty

How is type 1 diabetes treated

Insulin injections

Glucose is take up from bloodstream

Limit simple carbohydrates

W Is type 2 diabetes treated

Reduce carbohydrates in diet

Losing weight and increasing exercise

Drugs to make insulin more effective