biology topic 5 - homeostasis and responce

Sensory neurone ?

Detect a stimulus, change in environment. An impulse is sent along them

Homeostasis?

The regulation of the conditions inside the body to maintain a stable internal environment in response to changes in both internal and external conditions

Motor neuron?

Carry nerve impulses away from CNS , end in an effector (muscle or gland)

Synapses?

• impulse arrives at axon terminal (electrical impulse)

• Neurotransmitter released from axon terminal

• Impulse is turned into a chemical transmitter

• Crosses synapse

Reflex arc?

• Receptor

• Sensory neurone

• cns

• Relay neurone

• Motor neurone

• Effector

Cerebellum?

• bottom back of brain

• Movement + balence

cerrebul cortex

• top of brain

• Intelligence, personality , consciousness thought etc

Medulla?

• sticks down

• Controls unconscious though eg heart rate

Stimulation ?

• weak electrical current, patients describe what they can feel

• Motor areas stimulated causes involuntary movements

• Visual area stimulates causes flashed of colour

• EEG’s can be created to study electrical activity in brain

MRI?

• magnetic resonance imaging

• Strong magnetic field + radio waves to show detailed brain start true and function

• Patients perform tasks, studying scans shows which parts of brain are active

Structures of the eye

• lens - refracts light to retina

• Retina - contains receptors cells called rods + cones, sensitive to light

• Sclera - tough outer coating to protect eye

• Cornea - where 70% of light is refracted into eye

• Optic nerve - where information is collected, nerve impulses from retina carried to brain

• Iris - controls amount of light entering eye

• Ciliary muscles + suspensory ligaments- change shape of lens

• Pupil - hole which lets light into eye

Seeing in dim light

• Radial muscles contact

• Circular muscles relax

Seeing in bright light

• radial muscles relax

• Circular muscles contract

Seeing close object

• fat / thick lens

• Bends light more

Seeing far objects

• thin lens

• Light bends less

short sighted

• myopia

• Lens too fat all Time

• Image falls in front of retina

• Fix with concave lens

Long sighted

• hyperopia

• lens too thin all the time

• Image forms behind retina

• Fix with convex lens

Corrective methods for eyesight ?

• contact lenses

• Laser eye surgery

• Lense implants

FSH

Causes egg to mature

Pituitary Gland

Reproductive hormone interactions

Oestrogen - stimulates LH, prohibits FSH

Progesterone - inhibits LH + FSh

Oestrogen

Causes growth of uterus lining

Progesterone

Maintains uterus lining

Hormonal contraceptives?

• the pill

• Implant

Non hormonal contraceptives

• condom

• Surgical methods

• Abstinence

• Interutarian device

female infertility

• lack of female hormones (LH + FSH)

• Results in no ovulation or damaged follopian tubes

Male infertility

• low sperm count or soerm not functioning correctly

Fixing lack of ovulation

• FSH and LH can be delivered artificially to stimulate egg to mature and release from ovary

IVF

• used when fallopian tubes are damaged or blocked

• Donee egg used

• Sperm is of low quality (individual sperm inserted into egg)

• No obvious cause for infertility

Process of IVF

• egg production (stimulated hormone therapy )

• Egg retrieved from ovary

• Sperm sample provided

• Egg + sperm combined to allow fertilisation

• Fertilised egg introduced into uterus

LH

Causes egg to release

Pituitary Gland