B10 The nervous system, eye and brain Flashcards
What is homeostasis
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function
What 2 conditions need to be maintained for optimum enzyme action
pH
Temperature
What is negative feedback
When a change away from the ideal triggers a reaction to bring the change back to normal
What 3 things need to be controlled by negative feedback
Water levels
Body temperature
Blood glucose concentration
What are receptors
Detect changes in the internal or external environment
What are stimuli
A change in the environment
What is an effector
A muscle of gland that brings out a response
What is a coordinator
Areas that receive and process information from receptors
Give 5 examples of coordinators in the body
Brain
Pancreas
Nervous system
Endocrine system
Spinal cord
Describe the function and structure of the sensory neurone
Connects the receptor to the CNS
Has a nucleus
Myelin sheath for insulation
Has axon
Cell body is in the middle
Describe the function and structure of the motor neurone
Connects CNS to muscles/glands
Has a nucleus
Myelin sheath for insulation
Has axon
Cell body is at the end
How does the body respond to a stimulus
The receptor cell detects the stimulus
An electrical impulse is sent via nerves along the sensory neurone to the CNS
The CNS coordinates the response
An electrical impulse is sent along the motor neurone to a muscle or gland
This triggers a response
What is the central nervous system made up of
Spinal chord and brain
What are the 4 sense organs and what receptors do they contain
Eyes-Light
Ears-Sound, pressure
Nose-Chemical(smell)
Skin-Pain, pressure, change in temperature
Name 2 effectors and how they respond to impulses
Muscles-Contract
Glands-Secrete hormones
What is the relay neurone
Connects sensory and motor neurone and is involved in a reflex action
What is a synapse
Junction between 2 neurones
How does a synapse work
The impulse arrives at the end of the axon
Chemical messengers called neurotransmitters are released
These chemicals diffuse across the synapse and bind with receptor molecules on the membrane of the second neurone
The binding of the neurotransmitter to the receptor stimulates the second neuron to transmit an electrical impulse
What is the function of the cerebral cortex
Concerned with consciousness, intelligence, memory and language
What is the function of the hypothalamus
Controlling body temperature
What is the function of the pituitary gland
Secretes hormones
Produces chemicals
What is the function of the cerebellum
Coordinating
muscular activity and balance
What is the function of the medulla
Unconscious activities such as controlling heartbeat, movement of gut and breathing
What is the function of the:
Pupil
Cornea
Ciliary muscles
Retina
Blind spot
Optic nerve
Lens
Iris
Pupil-Lets in light
Cornea-Protects eye and refracts light
Ciliary muscles-Changes the shape of the lens
Retina-Contains light sensitive cells to detect image
Blind spot-Where the optic nerve needs the retina
Optic nerve-Sends electrical impulses to the brain
Lens-Focuses objects
Iris-Changes the shape of the pupil
What is accomodation
Focus on near or far objects
When focusing on something close, what do the muscles in you eye do
Ciliary muscles contract
Suspensory ligaments relax
The lens thickens
What happens in the eye in bright light
The pupil constricts
Radial muscles relax
Circular muscles contract
What happens in the eye in din light
Pupil dilates
Radial muscles contract
Circular muscles relax
When focusing on something far away what do the muscles in the eye do
Ciliary muscles relax
Suspensory muscles contract
Lens becomes thin
What is myopia and what lens does it require
Short sightedness
Biconcave lens-Brings rays further apartW
What is hyperopia and what lens does it require
Long sightedness
Biconvex lens-Brings rays closer together
