B10 The Nervous System Flashcards
10.1 What is Homeostasis
It is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.
10.1 Why is Homeostasis important
It is important for maintaining optimal conditions for enzyme action and all cell functions.
10.1 What does Homeostasis usually include?
It includes control of blood glucose concentration, body temperature and water levels.
10.1 What type of responses do automatic control systems involve?
Nervous or chemical responses.
10.1 What do control systems include?
Receptors, coordination centres and effectors.
10.2 What does the nervous system do?
It uses electrical impulses to your surroundings and coordinate your behaviour.
10.2 What do receptors do?
They are cells which detect stimuli (changes to the environment).
10.2 What happens after you receive a stimulus in a Nervous system?
Impulses from recptors pass along sensory neurones to the brain or spinal cord (CNS). The brain coordinates the response, and impulses are sent along motor neurones from the brain (CNS) to the effector organs.
10.2 How does the nervous system work (summed up)?
Stimulus —> Receptor —> Coordinator (CNS) —> Effector
10.3 What are reflex actions
They are actions that are automative and rapid and do not involve conscious parts of the brain.
10.3 What do reflexes involve?
They involve sensory, relat and motor neurones.
10.3 What do reflex actions control?
They control everyday bodily functions, such as breathing and digestion, and help you avoid danger.
10.3 What are the main stages of reflex actions?
Stimulus —> Receptor —> Sensory Neurone —> Relay Neurone —> Motor Neurone —> Effector —> Response
10.4 What is the brain?
It has interconnected neurones that control complex behaviour.
10.4 What is the cerebral cortex?
It is concerned with consciousness, intelligence, memory and language.
10.4 What is the cerebellum?
It is concerned mainly with coordinating muscular activity and balance,
10.4 What is the medulla?
It is concerned with unconscious activities such as controlling the heartbeat, the movements of the gut and breathing.
10.4 How do scientists study the brain?
They map regions of the brain to their functions by studying patients with brain damgae, by electrically stimulating different areas of the brain, and by using MRI scanning techniques.
10.5 What is the eye?
It is a sense organ that contains receptors in the retina that are sensitive to light intensity and colour.
10.5 What is the sclera?
It has a transparent region at the front called the cornea that lets the light in and refracts light towards the retina.
10.5 What is the iris?
It controls the size of the pupil and the amount of light entering the eye.
10.5 What are the cilary muscles and suspensory ligaments?
They change the shape of the lens to fine focus light on the retina.
10.5 What is the optic nerve?
It carries impulsesfrom the retina to the brain.
10.6 What is accommodation?
It is the process of changing the shape of the lens of the eye to focus on near or distant objects.
10.6 How do your eyes focus on close objects?
The cilary muscles contract, the suspensory ligaments loosen, and the lens becomes thicker so ot can refract light rays strongly.
10.6 How do your eyes focus on distant objects?
The cilary muscles relax, the suspensory ligaments are pulled toght, and the lens is pulled thin so it only refracts the light rays slightly.
10.6 How can sight defects be treated?
It is done using spectacle lenses, hard and soft contact lenses, laser surgey, and repkacement lenses in the eye.
