Unit 5 biology Flashcards
What is homeostasis
The maintenance of the body’s constant internal environment that uses negative feedback systems to keep it in balance
What 4 things does homeostasis control
-Blood glucose concentration
-Body temperature
-Water levels
-Hormone levels
What do automatic control systems do
detect changes in the body by using neural and hormonal communications
What 3 things do all control systems have
Receptors, coordination centers, effectors
How do receptors work
They detect stimuli and convert them into electrical impulses
Difference between sensory and motor neurons
Sensory neurons take electrical signals to the Coordination centre.
Motor neurons take electrical signals from coordination centres
How do coordinations centres receive information and what do they do with it
Electrical signals travel up sensory neurons up to the CNS where it processes the information and sends another electrical impulse
How do effectors work
Electrical signals from the CNS are sent along motor neurons and the effectors carry out the response
Why does the body have reflex arcs
To make sure that we receive minimal damage from sources of danger such as boiling water
What are synapses
Gaps between neurones where information gets transferred across
How does a synapse work
When the impulse reaches the end of the first neuron, chemicals are released and move across the synapse. When the chemical reaches the second neuron, the impulse restarts
How do we test reaction time
Ruler drop test
Describe the cerebral cortex
Cerebral cortex- controls consciousness, intelligence, memory and language. The outer part of the brain
Describe the cerebellum
Controls the fine movement of muscles. A round structure at the back of the brain
Describe the medulla
Controls unconscious action such as breathing and heart rate. Found in the brain stem.
Why so it difficult to investigate the brain
-complex and delicate
-easily damaged
-membranes around the brain stop drugs from getting to it
-we still don’t know everything each part of the brain does.
How can neuroscientists map out the brains structure
-studying patients with brain damage as if we know what part of the brain is damaged, we know what is does
-MRI scan make detailed images of the brain
-electrically stimulating the brain with electrodes to see which parts are affected
What is negative feedback
When the body detects a change in hormone levels, it counteracts the changes to return the body to normal levels.
Describe the retina in the eyes
Layer of light sensitive cells at the back of the eye. When light hits it, it stimulates the cells to send a signal to the brain in order to render an image
Describe the optic nerve in the eyes
The nerve that leads from the eye, to the brain which carries the impulses made by the retina
Describe the sclera in the eyes
White outer layer which supports the rest of the eye’s structure. Prevents dame to the rest of the eye
Describe the cornea in the eye
Allows light through at the front of the eye. The curved face bends to focus light onto the retina.
describe the iris in the eye
Muscles that expand and contract around the pupil.
The muscles expand in darkness to allow for better vision
The muscles contract in bright light to avoid retina damage
describe ciliary muscles and suspensory ligaments in eyes
Holds the lens in place to control its shape
