Homeostasis and the Nervous System Flashcards
What is the nervous system?
A system that enables humans to react to their surroundings and to coordinate their behaviour.
What is the structure of the nervous system?
The CNS (brain and spinal chord) and a network of nerves.
Name the 5 things in the nervous system responses process.
Stimulus, receptor, coordinator, effector, response
Reflex arc: what is the first neurone that an electrical impulse is sent to?
Sensory neurone.
What is a stimulus?
A change in the environment.
What does a receptor do?
Detects a stimulus and sends electrical impulses along neurones.
What is a coordinator and what does it do?
The CNS coordinates the body’s response.
What does an effector do? Give an exampe.
Brings about a response.
I.e: muscle contracting, glands secreting.
Reflex arc: what is the second neurone that an electrical impulse is sent to?
Relay neurone.
Reflex arc: what is the third neurone that an electrical impulse is sent to?
Motor neurone.
What is a synapse?
The gap (‘junction’) between two neurones which allow for electrical impulses to be passed along.
How do synapses work? (3 steps)
- Impulse arrives in neurone.
- Sacs in neurones release chemicals into the gap.
- Chemicals attach to the surface of the next neurone and set up a new electrical impulse.
What is the cerebal cortex important for?
Consciousness, intelligence, memory, language
What is the cerebellum important for?
The coordination of muscle activity.
What is the medulla oblongata important for?
Unconscious activities like breathing and the heart beating.
Where is the cerebral cortex located?
At the front of the brain.
What does the cerebellum look like?
A strawberry.
Remember: the locations of the hypothalamus and the pituitary gland!
What do the ciliary muscles do to focus on a near object?
Contract.
What do the suspensory ligaments do to focus on a near object?
Slacken.
What is the structure of the lens when focusing on a near object and why?
Thicker and more curved - to refract light rays more strongly.
What type of lens is used to correct hyperopia?
Convex.
What type of lens is used to correct myopia?
Concave.
What is homeostasis?
The regulation of internal conditions (of a cell or whole organism) in response to external or internal stimuli to maintain optimum conditions for functioning.
What does homeostasis include in the human body?
Blood glucose concentration, body temperature, water levels
What 4 steps happen when the body temperature is too high?
- Stimulus of temperature change detected by effector.
- Blood vessels dilate (vassodilation)
- Sweat is produced from the sweat glands.
- Energy is transferred from skin to environment, so body temperature falls.
+ In exam, also include about thermoregulatory centre and electrical impulses.
What 4 steps happen when the body temperature is too low?
- Stimulus of temperature change detected by effector.
- Blood vessels constrict (vassoconstriction)
- Sweating stops and skeletal muscles contract, causing shivering.
- Body temperature rises.
+ In exam, also include about thermoregulatory centre and electrical impulses.
What is the thermoregulatory centre?
The part of the brain which controls body temperature.
Why are reflex actions described as ‘rapid and automatic’?
They do not involve the conscious part of the brain.
Remember: learn about required practical (reaction time)
