B10 - The Human Nervous System Flashcards
Define homeostasis
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.
Internal conditions that are controlled include?
Body temperature
The water content of the body
Blood glucose concentration
Define receptors
Cells that detect changes in the internal and external environment.
Define stimuli
Changes in the internal or external environment.
Define coordination center
Areas that receive and process the information from the receptors. They send out signals and coordinate the response of the body.
What do coordination centres include?
The brain, the spinal cord, and some organs such as the pancreas
Define effectors
Muscles or glands that bring about responses to the stimulus that has been received. These responses restore conditions in the body to the optimum levels.
Define neurones
Special cells that pass an electrical impulse sent from a sensory receptor when it detects a stimulus.
Where are neurones found?
They are found in bundles of hundreds or even thousands of neurones known as nerves.
What do impulses travel along neurones to?
The central nervous system (CNS)
What is the central nervous system (CNS) made up of?
The CNS is made up of the brain and the spinal cord.
Define sensory neurones
The cells that carry impulses from your sense organs to your central nervous system (CNS).
Define motor neurones
Motor neurones carry impulses from the central nervous system (CNS) to the effector organs.
What order do things happen in the nervous system?
Stimulus 》receptors 》coordinators (CNS) 》effector
Define reflex
An automatic responses like blinking, pulling your hand back, etc…
What are the three types of neurones?
Sensory neurones
Motor neurones
Relay neurones
Define relay neurones
Connect sensory neurone and a mother neurone, and are found in the (CNS)
What is the pathway of a reflex arc?
Stimulus 》receptor 》sensory neurone 》relay neurone 》motor neurone 》effector 》response
Define meninges
The protective membrane that encases the brain.
What is the cerebral cortex in control of?
Consciousness, intelligence, memory and language.
What is the cerebellum in control of?
Coordinating muscular activity and balance.
What is the medulla in control of?
Unconscious activities such as controlling the heartbeat, the movements of the gut, and breathing.
What is the light-sensitive layer in the back of the eye called?
Retina
What happens to the eye when the light is bright?
The circular muscles contract, radial muscles relax, and the pupils constrict.
What happens to the eye when the light is dim?
Circular muscles relax, radial muscles contract, and the pupils dilate.
What changes the shape of the lens to fine focus light on to the retina?
The ciliary muscles and suspensory ligaments.
What does the optic nerve do?
The optic nerve carries impulses from the retina to the brain.
What is the sclera?
The sclera is a tough outer layer that has a transparent region at the front called the cornea that let’s light in that refracts (changes the direction of) light towards the retina.
Define myopia
Short sightedness
Define hyperopia
Long sightedness
Define accommodation in terms of the eye
The process of changing the shape of the lens of the eye to focus on near or distant objects.
What happens to the eyes when they need to focus on close objects?
To focus on close objects, the ciliary muscles contract, the suspensory ligaments loosen, and the lens becomes thicker so it can reflect light rays strongly.
What happens to the eyes when they need to focus on distant objects?
To focus on distant objects, the ciliary muscles relax, the suspensory ligaments are pulled tight, and the lens becomes thiner so it can reflect light rays slightly.
How can sight defects be treated?
Spectacle lenses, hard and soft contact lenses, laser surgery, and replacement lenses in the eye.
