B10(Human Nervous System) Flashcards
What is a stimulus
A change in the environment
What’s parts make up the the central nervous system
-Brain
-Spinal cord
What’s the function of CNS
-Make quick, short term reactions to the environment
-coordinate behaviour
What are receptors
Organs containing specialised cells that enable us to detect changes in the environment
What is the impulse pathway for the nervous system
Stimulus-> receptor-> neurone-> coordination centre-> neurone-> Effector-> response
What are neurones
Specialised cells that conduct electrical impulses through out the body
What are nerves
A bundle of many more fibres enclosed within a protective sheath
-nerve fibres are the long axons of neurones together with any associated tissue
What are dendrites
Thin projections that extend from the cell body to connect with other neurones allowing electrical impulses to pass from one to the other
What is the myelin sheath
The axons of most neurones are wrapped in a insulating layer
What does the sensory neurone do
Connects receptor to coordination centre
What does the motor neurone do
Connects coordination centre to effectors
What does the relay neurone do
Creates a shortcut between sensory and motor neurones for our reflexes
What are reflexes
Automatic response to stimuli
What is a reflex action
It is a rapid and automatic response of the nervous system that does not include conscious thought
What is a reflex arc
The nerve pathway followed by a reflex action
What is the reflex pathway
-receptor in skin detects a stimulus
-sensory neurone sends electrical impulses to relay neurone located in the spinal cord
-relay neurone connects the sensory neurone to the motor neurone
-motor neurone sends electrical impulses to effector which then produce a response
What is the pathway for a synapse
Electrical impulse->synaptic vesicle releases neurotransmitter-> diffusion of neurotransmitters-> receptor triggers electrical impulse-> electrical impulse
What is a synapse
A junction between 2 neurones across which electrical signals pass
What is the function of the cerebral cortex
Memory and language
What is the function of the cerebellum
Coordinates muscular activity and balance
What is the function of the hypothalamus
Regulates temperature
What is the function of the medulla
Unconscious activities such as controlling the heart rate and breathing rate
What is the function of the pituitary gland
Endocrine master gland
What is the cornea
Refracts light to the lens to help focus
What is the Iris
Muscles contract or relax to control the amount of light entering the eye
What is the pupil
The hole that allows light into the eye
What is the ciliary muscle
Contracts or relaxes to change the lens thickness
What is the Suspensory ligament
Hold the lens in place
What is the retina
Contains light sensitive cells to send impulses to the optic nerve to the brain
What is the sclera
Thick and tough for protection
What is the optic nerve
Transmits impulses to the brain
What is accommodation
The process of altering the shape of the lens to focus on near or distant objects
What happens if there’s too much bright light in the eye
-Circular muscles contract
-radial muscles relax
-pupil constricts
What happens in dim light in the eye
-Circular muscles relax
-radial muscles contract
-pupil dilates
What does the eye do to focus on a near object
-the suspensory ligaments loosen
-the lens is then thicker and refracts light rays strongly
What does the eye do to focus on a distant object
-Ciliary muscles relax
-suspensory ligaments are pulled tight
-the lens is then pulled and only slightly refracts light rays
What is the scientific term for short sightedness
Myopia
What is the scientific term for Long sightedness
Hyperopia
