B5

what part of the nerve cell is this ?

dendrites

what part of the nerve cell is this ?

Axon

what part of the nerve cell is this ? (green part )

nucleus

what part of the nerve cell is this ?

myelin sheat

what does the myelin sheath do ?

covers the axon of some neurons and helps speed neural impulses

what part of the nerve cell is this ?

axon terminal

What is thermoregulation?

regulation of body temperature

What is homeostasis?

the regulation of internal conditions in the body

what organ controls homeostasis

the brain and the spinal cord

Why does homeostasis occur?

happens bc of he coordination of your nervous system , your endocrine system and your body organs all working together

________ contols homeostasis

hypothalamus

What does the pituitary gland do?

Secretes hormones to regulate other glands.

what is a gland

a group of cells which release smth e.g. tears , saliva , hormones

what is the nervous system made up of

lots of interconnected neurones

whats a hormone

a chemical messenger

the endocrine system consits of g________ which release __________ that are carried in the b__________

glands , hormones , blood

what should your core body temp be

37

the h_____________ detects if your core body temp is too high/low

hypothalamus

the hypothalamus contains ___________ receptors to detect the temp of the blood

temperature

what are the two parts of the nervous system

central nervous system and peripheral nervous system

What does the nervous system do?

controls our muscles and glands by sending electrical impulses

stimuli

Changes in the environment

receptors

found on sensory organs they detect the stimuli

order of a voluntary pathway

1- stimulus

2- receptors detect stimulus

3-electrical impulse goes along sensory neurone

4-it reaches CNS decides on action

5-electrical impulse goes along motor neurone to effector (muscles/glands)

6-response happens

what is a reflex

a fast , involuntary response that protects from harm which doesn't involve the conscious parts of the brain .

reflex arc pathway

1-stimulus

2-receptors detect stimuli

3-electrical impulse travels up sensory neurones

4-relay neurone ->spinal chord which decides on action

5-new electrical impulse down motor neurone

6-to effector

Note - between neurones info passes between a synapse as a chemical

cerebral cortex

highly folded outer layer connected with consciousness ,intelligence ,memory ,language

Cerebellum

coordination of muscle activity

medulla

controls unconscious activities like breathing and your heartbeat

why is treating brain disorders so difficult

the brain is so complex and different regions cant be studied in isolation

MRI

Magnetic resonance imaging

A technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain

-cancer cells , clots +abnormal blood flow

MRI advantages

non invisible

-no ionising radiation

-safer than CT scans

-vv safe detailed images

- non invasive

MRI disadvantages

- expensive

- not portable

- not suitable for everyone

EEG scans

Measures electrical activity within the brain via electrodes can detect epilepsy fits +memory problems

EEG scans advantages

no electricity

-vv safe

- can show abnormal brain changes

-maps brain activity

EEG scans disadvantages

cant detect cancer

CT scans

Multiple X-Rays of successive slices of the brain. Looks at brain structure.

CT scans advantages

- detailed x rays

- diagnoses conditions

- monitors conditions

- guides further tests or treatment

-non invasive

-quick

CT scans disadvantages

-not portable

-risk of ionising radiation

brain surgery benifits

maybe needed in case of a tumor in brain to save / prolong life

risks Brain surgery

may cause brain damage and infection -possible stroke

brain implants benefits

can help the brain function

brain implants risks

may cause brain damage

radiotherapy chemo therapy benefits

destruction of tumours (can save lives )

radio/chemotherapy risks

can damage normal cells

monoclonal antibodies benefits

offer hope in treatment of cancer /tumor

monoclonal antibodies risks

skin changes e.g. red and sore skin or itchy rash

stem cell therapies benefits

offer help in repairing damages to nervous system tissue

stem cell therapies risks

stem cells may be rejected . ethical / moral issues

factors which increase reaction time

distractions , alcohol , fatigue

factors which decrease reaction time

practice , caffeine , no distractions

ways ruler practical could be improved

could use a computer to calculate reaction times

- perform investigation on several other people

- use more different time intervals

how do we see ?

light enters cornea which reflects light inwards . light goes through the pupil (controlled by the iris ) . light is refracted more by the lens which is a convex shape onto the retina . the receptors on the retina convert light into electrical impulses , which are sent to the brain via the optic nerve .

in a dark room what happens to your pupils ?

they get bigger

- radial muscles contract

-circular muscles relax

- pupil dilates

- more light enters

in a bright room what happens to your pupils

- get smaller

- radial muscles relax

-circular muscles contract

- pupil constricts

-less light enters

the light that reaches your eyes from distant objects is travelling in ________ rays

parallel

the light that reaches your eyes from a nearer object is d_______ strongly

diverging

what is accommodation

the process of changing the shape of the lens with the help of the ciliary muscles and suspensory ligaments

soft lense (contact lenses )

-made from silicone gel

-permeable to allow oxygen to enter the cornea

-more comfortable

hard lenses (contact lenses )

-rigid

-durable

-less comfortable

-longer lasting

what does laser eye surgery do

changes the shape of the cornea

side effects of laser eye surgery

blurred vision -infection

What does negative feedback do?

maintains homeostasis and counteracts change to keep your internal environment stable

What is the CNS composed of?

brain and spinal cord

What is the CNS connected to the body by in mammals ?

Sensory and motor neurones

What are sensory neurons?

The neurons that carry information as electrical impulses from the receptors to the CNS

What are motor neurons?

The neurons that carry electrical impulses from the CNS to effectors

What are effectors?

All your muscles and glands, which respond to nervous impulses

What is a synapse?

Gap between two neurons

Two examples of receptors

Taste receptors on the tongue and sound receptors in the ears

What do effectors do?

muscles contract and glands secrete hormones

What happens at a synapse?

When a nerve impulse reaches the synapse at the end of a neuron, it cannot pass directly to the next one. Instead, it triggers the neuron to release a chemical neurotransmitter. The neurotransmitter drifts across the gap between the two neurons and then sets off a new electrical signal in the next neurone

what different methods do scientists use to study the brain ?

studying patients with brain damage , electrically stimulating the brain , MRI scans

the tough, supporting wall of the eye

the sclera (K)

what is The cornea (B)

Transparent outer layer of the eye

what does the cornea do ?

Refracts light into the eye

what is the iris (E)

a ring of muscle tissue that forms the coloured portion of the eye around the pupil and controls the size of the pupil opening

what is the lens (H)

the transparent structure behind the pupil that focuses light onto the retin

the shape of the lens is controlled by __________

ciliary muscles and suspensory ligaments

the optic nerve

the nerve that carries neural impulses from the receptors on the retina to the brain

which letter is the sclera

F

which letter is the cornea ?

E

which letter is the lens ?

B

what letter is the iris ?

A

which letter is the optic nerve ?

L

To look at near objects _____

The ciliary muscles contract, which slackens the suspensory ligament.

The lens becomes fat (more curved)

This increases the amount by which it refracts light

To look at distant objects _____

The ciliary muscles relax, which allows the suspensory ligaments to pull tight

This makes the lens go thin (less curved)

So it refracts light by a smaller amount

Why are long sighted people unable to focus on near objects?

their lens is the wrong shape and doesn't refract the light enough or their eyeball is too short and so the images of near objects are brought into focus behind the retina .

what can help longsightedness

glasses with a convex lens to refract the light rays so they focus on the retina

what is the medical term for longsightedness

hyperopia

Why are short sighted people unable to focus on distant objects?

their lens is the wrong shape and refracts light too much or their eyeball is too long and so the images o distant objects are brought into focus in front of the retina

What can correct myopia?

glasses with a concave lens so the light rays focus on the retina

Alternatives to wearing glasses

Contact lenses, laser eye surgery and replacement lens surgery.

When you're too hot

hairs lie flat

sweat is produced by sweat glands and evaporates from the skin which transfers energy to the environment .

the blood vessels supplying the skin dilate so more blood flows close to the surface of the skin . this called vasodilation which helps to transfer energy from the skin to the environment .

What is vasodilation?

the dilatation or widening of blood vessels, which decreases blood pressure.

when you're too cold

Hairs stand up to trap an insulating layer of air

No sweat is produced

Bloody vessels supplying the skin capillaries constrict to close off the skins bloody supply. This is called vasoconstriction

When you're too cold you shiver too (your muscles contact automatically). This needs respiration, which transfers some energy to warm the body

Thyroid gland

produces thyroxine which helps to regulate things like the rate of metabolism , heart rate , and temperature

what is metabolism ?

sum of all chemical reactions in the body

Adrenal gland

A pair of endocrine glands that sit just above the kidneys and secrete hormones that produce adrenaline for a 'fight or flight ' response

Nerves vs Hormones

Nerves - very fast, act for a short time, act on a very precise area.

Hormones - slower, act for a long time, act in a more general way.