Brain, Eyes and Nerves

cerebellum

a part of the brain that coordinates voluntary movements, balance and posture

cerebral hemispheres

the largest part of the brain responsible for memory, intelligence, reasoning and language

medulla oblongata

the part of the brainstem that controls unconcious activities, such as breathing, heart rate and swallowing

CT scanning

a technique that uses X-rays to create detailed images of the brain’s structure, helpful in diagnosing brain injuries or tumors

PET scanning

a method to investigate brain function by detecting areas of activity. Radioactive tracers show how the brain processes glucose or oxygen

complexity limitation of treating brain damage

the brain is not fully understood/different regions have intricate functions

delicate tissue limitation of treating brain damage

surgical produces can cause additional damage

inaccessibility limitation of treating brain damage

some areas of the brain are difficult to reach

Sensory neurons

neurons that carry electrical impulses from sensory receptors (e.g., skin, eyes) to the central nervous system (CNS)

relay neurons

Neurons that transmit electrical impulses within the CNS, often connecting sensory and motor neurons

motor neurons

Neurons that carry impulses from the CNS to effectors (e.g., muscles or glands), triggering a response

dendron

A short, branched structure of a neuron that carries electrical signals toward the cell body

axon

A long, thin extension of a neuron that carries electrical signals away from the cell body

myelin sheath

a fatty layer surrounding the axon, which insulates and speeds up the transmission of electrical impulses

synapse

the junction between two neurons where chemical signals (neurotransmitters) are transmitted

reflex arc

the pathway taken by electrical signals in a reflex action

stimulus (involved in reflex arc)

a change in the environment (eg heat)

receptor (involved in reflex arc)

a specialised cell or organ that detects the stimulus

sensory neuron (involved in reflex arc)

transmits the signal to the CNS

relay neuron (involved in reflex arc)

connects sensory and motor neurons in the spinal cord

motor neuron (involved in reflex arc)

sends the signal to the effector

effector (involved in reflex arc)

a muscle or gland that performs the response (eg moving your hand away from a hot object)

cornea

The transparent outer layer of the eye that helps refract (bend) light to focus it on the retina

lens

A flexible, transparent structure in the eye that further refracts light to focus it on the retina

iris

the coloured part of the eye that controls the size of the pupil and the amount of light entering the eye

retina

The layer at the back of the eye containing light-sensitive cells (rods and cones)

rod cells

detect light intensity and enable vision in dim light

cone cells

detect colour and work best in bright light

cataracts

a condition where the lens becomes cloudy, reducing vision

treatment for cataracts

replacing the lens with an artificial one

short-sightedness (myopia)

A vision defect where distant objects appear blurry because the light focuses in front of the retina

correction for short-sightedness (myopia)

concave lenses

long-sightedness (hyperopia)

a vision defect where close objects appear blurry because the light focuses behind the retina

correction for long-sightedness (hyperopia)

convex lenses

colour blindness

an inherited condition where individuals cannot distinguish certain colours due to defects in cone cells

what is BMI

body mass index (a measure of obesity)

BMI calculation

BMI = Mass (kg) / Height (m)²

what is a high BMI linked to

obesity, which increases the risk of type 2 diabetes, heart disease and strokes

risks of alcohol

consuming alcohol in excess can cause liver diseases such as cirrhosis and increase the risk of high blood pressure and heart disease

smoking

smoking damages arteries and increases the risk of cardiovascular diseases.

what can smoking lead to

lung cancer and chronic obstructive pulmonary disease (COPD)