Systems test 2026

Sensory receptors

• Chemoreceptors

• Mechanoreceptors

• Photoreceptors

• Thermoreceptors

• Pain Receptors

Chemoreceptors

• Detects chemical from different molecules and changes them into electrical signals

• found in mouth (taste), nose (smell), internal organ (sensitive to the composition of body fluids)

• There is a strong link between emotions and smells. a certain smell can trigger very strong emotions or memories

Mechanoreceptors

• Sensitive to touch, pressure, sound and motion and are located in the skin, the inner ear and muscles.

Photoreceptors

• Sensitive to light and are located in the back of the eyes (retina)

• rods and cones assist to see

rods

• these sensors function in low light and are found at the edges of the retina.

• also aid in peripheral vision

cones

• work best in bright light, detecting fine details and colour

• 3 types of cones- blue, red, green

• Colour blindness is caused when any of these cones aren’t present

Thermorecpetors

• Sensitive to temperature changes (hot or cold)

• Brain interprets these messages as hot or cold

• INTERNAL- hypothalamus

• EXTERNAL- skin

Pain receptors

• Sensitive to chemical changes in damaged cells and are located throughout the body, but most are located in the skin

• Send nervous impulses to sensory neurons which carry the nerve impulses to the CNS

CNS

• Stands for central nervous system

• The control centre of the body

• made up of brain and spinal cord

• mostly consists of interneurons

• receives all incoming messages from the environment and processes them

PNS

• peripheral nervous system

• made up of all the nerves outside the CNS

• Carries information from the body to the CNS and back again to the body

• Two parts- autonomic and somatic

autonomic part of PNS

• controls involuntary actions like

heartbeat, respiration, digestion and perspiration

• Has two parts

para systematic- rest and digest, slows down heart rate

sympathetic- fight or flight, speeds up heart rate

somatic part of PNS

• controls voluntary muscle movements

walking, waving

draw and label a neuron

cell body

• aka soma

• contains nucleus

dendrites

• very sensitive tree like extension attached to the cell body

• receive nerve impulses (messages) from other nerve cells - the nerve signal is carried towards the cell body

axon

• thin fiber like extension from the cell body with branching at the end

• can be up to 1 m long

• sends nerve impulses to other nerve cells - the nerve signal is carried AWAY from the cell body, towards the synaptic terminals

myelin sheath

• fatty layer that covers axon

• helps speed up the nerve impulse

• protects the nerve impulses from crossing wires with other nerves

synaptic terminal

• aka axon terminal, motor end plate

• a bulb at the end of axon

• where the electrical message is passed across a synapse (small gap between neurons) to the next nerve cell dendrite

synapse

• gap between neurons

• electrical nerve impules cannot travel across a synapse

• messenger molecules neurotransmitters carry a chemical signal

neurotransmitter

• released from the axon on one side of the synapse and carries impulses to the dendrite on the other side of the synapse

process how electrical signals are passed down the axon to axon terminal

step 1. when the electrical impulse (signal) recheas the axon terminal, the vesicles release neurotransmitters into the synapse

step 2. the nerve impulse travels across the synapse via the neurotransmitters and is picked up by the dendrites on the next neuron

step 3. the chemical stimulates the nerve impulse then continues travelling down the dendrite of the next neuron towards the cell body

Sensory neurons

• detect changes in the environment via receptors and send messages to the brain

pain, receptors in the back, to the brain and spinal cord (CNS)

Motor neurons

• carry signals from the CNS to effectors

• Effectors are muscle cells or glands that put messages into effect

inter neuron neuron

• nerve cells that connect sensory neurons to motor neurons

• link sensory neurons directly to motor neurons

• they are the most common neuron

• only make connections with other neurons

reflexes

• fast, simple, automatic and involuntary responses to stimuli, always causing the same motor response

• involves the peripheral nerves and often the spinal cord but not the brain

• helps protect body from damage

sequence of reflexes

Stimulus- change in environment (senses)

Sensory receptor- detects change (eyes, skin, etc)

Sensory neuron- carries signal from receptors to spinal cord

Interneuron- relays the signal from sensory neuron to motor neuron

Motor neuron- carries signal to effector cells

Effector cells- cause responses (muscle cells)

draw and label reflex arc

cerebrum

• majority part of brain

• controls conscious thoughts (senses, thinking and memory) and voluntary movements

• receive sensory messages from your body

4 lobes of cerebrum

• frontal lobe

• occipital lobe

• parietal lobe

• temporal lobe

draw the brain

frontal lobe

• front of the brain

controls

• personality

• the way you communicate

• movement of the body

• concentration

• planning and problem solving

• meaning of words

• emotional reactions

• smell

occipital lobe

• Back of the brain

• Visual processing and gets its information from the eyes

• Different areas of the occipital lobe look after spatial perception, colour and movement

parietal lobe

• Senses and interpreting things

• visual interpretation

• processing of language and maths

• responsible for spatial awareness and navigational skills

• body awareness

• touch and pressure

• taste

temporal lobe

• either side of the brain

• closely linked to hearing

• processes what your hear into things that makes sense, including language

• responsible for object recognition (including face

• where long-term memories are processed)

• emotions

• smell

thalamus

• inside the brain

• process sensory info and sends it to cortex

cerebellum

• underneath the brain near the occipital lobe

• responsible for motor control (movements) of motor coordination, balance and posture

brainstem (parts)

• Goes to form the spinal cord

• medulla- controls automatic functions like breathing and digestion

• pons- assists in automatic functions

• midbrain- receives and processes sensory info like movement

spinal cord

• the information superhighway to the nerves, connecting the brain to the rest of the body

• it runs from the brain to the bottom of your spine and is protected by the spinal column

• brain & spinal cord is CNS

white matter

• Parts of the CNS that contain neurons covered in myelin

• these areas are where the axons are connecting different parts of gery matter to each other

grey matter

• parts with mainly cell bodies, dendrites and synaptic terminals (pinkish grey)

• this is where thinking occurs

the hemispheres

• the left sie of the brain controls the RIGHT side of the body

• the right side of the brain controls the LEFT side of the body