The nervous system Flashcards
Homunculus
a representation of a human whether size of the body part shows the number of receptors
Sense & sensitivity - sight
Stimulus – light
sense organ – eye
receptor - photoreceptor
Sense & sensitivity - hearing
Stimulus – sound
sense organ – ears
receptor - cochlea
Sense & sensitivity - taste
Stimulus – chemical
sense organ – tongue
receptor - chemoreceptors
Sense & sensitivity - smell
Stimulus – chemical
sense organ – nose
receptor - chemoreceptors
Sense & sensitivity - touch
Stimulus – pressure movement
sense organ – skin
receptor - sensory nerve endings
Sense & sensitivity - balance
Stimulus – change in position
sense organ – inner ear
receptor - semicircular canals
How the nervous system works e.g. flash of light
Stimulus (change in the environment) - flash of light
Receptor (detection of the change) – eye (retina)
sensory neuron:
coordinator (CNS) (integration of information) – brain
motor neurone:
effector (muscle or gland) - circular muscles in iris
response (contraction or secretion) - Iris contracts to reduce size of pupil to let less light in.
How the nervous system works e.g. hot object
Stimulus (change in the environment) - Hot object
Receptor (detection of the change) – heat receptor in skin
sensory neuron:
coordinator (CNS) (integration of information) – spine
motor neurone:
effector (muscle or gland) - arm muscles
response (contraction or secretion) - hand is withdrawn.
sensory neurone
A sensory neuron is a type of neuron that carries sensory information from the sensory receptors (such as those in the skin, muscles, and internal organs) to the central nervous system (CNS), including the brain and spinal cord. Sensory neurons are responsible for detecting various stimuli such as temperature, pressure, pain, touch, and light.
motor neurone
A motor neuron is a type of neuron that carries signals from the central nervous system (CNS) to muscles, glands, and other effector organs. Motor neurons are responsible for controlling muscle movements and are essential for all voluntary and involuntary movements.
relay neurone
A short neurone found in the CNS that links sensory neurons and motor neurones - allows control over reflex arcs
neural pathway
A neural pathway is a series of interconnected neurons that transmit signals between different parts of the nervous system. These pathways are responsible for carrying information throughout the body and are involved in controlling various physiological and behavioral functions.
reflex arc
A reflex arc is a neural pathway that mediates a reflex action. A reflex arc is a rapid, involuntary response to a stimulus that does not require conscious thought. Reflexes are important for protecting the body from harm, maintaining posture, and allowing for rapid responses to changes in the environment.
reflex arc / action after touching a hot object with a finger
- coordinated by spinal chord - NOT brain - this makes the reflex quick to minimise damage
- response is muscle contracting and pulling the hand away
synapse
A synapse is a junction between two nerve cells or between a nerve cell and a muscle cell, where information is transmitted from one cell to the other, in one direction. It is the point where the axon of one neuron meets the dendrite or cell body of another neuron.
The chemical travels across the gap by diffusion. The chemical is called a neurotransmitter.
cerebral cortex
The cerebral cortex is the largest, outermost layer of the brain and plays a crucial role in many important functions, including sensation, perception, movement, cognition, and consciousness. It is divided into four main lobes: the frontal lobe, parietal lobe, temporal lobe, and occipital lobe.
cerebellum
The cerebellum is a structure located at the base of the brain, beneath the cerebrum, and it is primarily involved in coordinating and fine-tuning movements, balance, and posture.
medulla oblongata
The medulla oblongata is a part of the brainstem that connects the brain to the spinal cord, and it is involved in several vital, unconscious functions necessary for life, including breathing, heart rate, blood pressure, and digestion.
parts of the cerebral cortex - Frontal lobe
largest lobe
controls:
-vouluntary movement
-language
- planning and organising
- behaviour and emotions
parts of the cerebral cortex - parietal lobe
This lobe is responsible for processing sensory information from the body, including touch, temperature, and pain, and integrating this information with other sensory and motor information to enable spatial orientation and perception.
-gives us a map of the world around us
parts of the cerebral cortex - temporal lobe
This lobe is involved in processing auditory information, including speech and language, as well as in recognizing faces and objects.
parts of the cerebral cortex - Occipital lobe
This lobe is responsible for processing visual information from the eyes and interpreting it to form a visual perception of the world.
Magnetic resonance imaging (MRI)
it uses strong magnetic fields and radio waves to produce very detailed images of the brain (any part of the body).
Magnetic resonance imaging (MRI) - pros
- non invasive
- doesn’t use ionising radiation.
- can detect cancer cells blood clots and abnormal blood flow.
Magnetic resonance imaging (MRI) - cons
- must stay very still.
- claustrophobic inside magnets
- not suitable for metal materials
How the brain used to be studied
initially the brain was studied by:
- looking at people with brain damage and comparing damage to behaviour
- stimulating the brain with electricity and seeing what happens
- X-ray scans e.g. CT scan
Electroencephalogram (EEG)
attach sensors all over the scalp to detect electrical signals made by the brain.
Electroencephalogram (EEG) - pros
Safe, can see unusual activity (Fitz, epilepsy, memory problems)
Electroencephalogram (EEG) - cons
needs highly trained specialists and only looks at signals e.g. can’t detect cancer
the human eye
retina
Contains receptor cells called rods and cones, which are sensitive to light
fovea
the maximum density of cone cells is found here, as most of the light from the lens is refracted to this point.
sclera
tough outer coating to protect the eye.
cornea
where 70% of the light is refracted into the eye
optic nerve
Where the information from the receptor cells collects and the nerve impulses from the Retina are carried to the brain
iris
Controls the amount of light entering the eye.
ciliary muscles and suspensory ligaments
changes the shape of the lens.
pupil
Hole which lets light into the eye
lens
Reflects light onto the retina.
pupil dialation
Stimulus - not enough light
Receptor - rod and cone cells
Coordinator – brain
Effector - radial muscles contract & circular muscles relax.
Response - people get bigger and less light enters
pupil contraction
Stimulus – too much light
Receptor - rod and cone cells
Coordinator – brain
Effector - radial muscles relax & circular muscles contract.
Response - people get smaller and less light enters
To focus on a near object:
To focus on a near object:
a lot of focusing is needed so
so ciliary muscles contract
suspensory ligaments loosen
lens is thicker and refract light strongly
rays of light converge on the retina
to focus on a distant object:
to focus on a distant object:
less focusing is needed
so ciliary muscles relax
suspensory ligaments are pulled tight
lenses is thinner & only slightly refract light rays
rays of light converge on the retina
myopia
Myopia is caused because the lens is too strong, or the eyeball is too long.
one way to correct myopia is to use spectacles or hard or soft contact lenses with concave lenses.
In myopia the image is focused in front of the retina
hyperopia
hyperopia is caused because the lens is too weak, or the eyeball is too short
One way to correct hyperopia is to wear spectacles or hard or soft contact lenses with convex lenses
in hyperopia the image is focused behind the retina
accommodation
The ability of the eye to change its focus by adjusting the curvature of the lens
