B3 Flashcards
What are sensory neurones?
- neurones that carry electrical impulses from the receptor cells to the CNS
What is the nervous system?
The nervous system consists of the brain and spinal cord which form the CNS and also several other neurones which respond to changes in the external environent
What are relay neurones
- neurones that carry the electrical impulses from sensory to motor neurones (in the CNS)
What are motor neurones?
- neurones that carry impulses from the CNS to the effectors
What are receptors?
- groups of cells that detect a stimulus
What are effectors?
- muscles or glands
- will either contract or release a hormone
What is the CNS
- the CNS is made up of the brain and spinal cord
What is a reflex action?
- an automatic/ involuntary action
- occur without thinking
- impulse will not go to brain
- e.g: Stimulus -> Receptor Cells -> Sensory Neurone -> Spinal Cord -> Motor Neurone -> Effector -> Response
- much faster by not using brain
Reflexes Practical?
- ruler drop time
- can be affected by levels of caffeine, mass of ruler, which hand
- use v2 - u2 = 2 to work out time
What does the cerebellum do?
- co-ordinates muscular activity + balance
- controls involuntary movements
What does the cerebal cortex manage?
- memories
- personality and complex emotions
- learning and conscious thought
What does the medulla do?
- controls essential automatic actions
- such as breathing and heart rate
What does the hypothalmus do?
- regulates temperature
- regulated water balance
What does the pituary gland do?
- known as the master gland
- stores and releases many hormones
How can you scan the brain?
- CT/ X-RAY scans (risk of radiation exposure)
- MRI (less risk of any radiation)
- Damage to the brain can be used to find brain functions
What is the sclera?
- tough white layer of the eye that protects it from damage
What is the cornea?
- transparent front part of the sclera that refracts light into the pupil
What is the pupil?
- The hole in the center of the eye through which light passes through
What is the iris?
- rings of muscles that control the size of the pupil
What is the retina?
-an area of light receptive cells at the back of the eye
What are receptor cells for colour in the eye?
- cone cells
- 3 types for red green and blue
What is the optic nerve?
- nerve which sends signals to the brain from the eye
What are rod cells?
- receptor cells which are sensitive to dim and bright light
What happens when there is low levels of light?
- Radial muscles contract
- Circular muscles relax
- more light is let in as pupil dilates
What happens when there is high levels of light?
- radial muscles relax
- circular muscles contract
- less light is let in as pupil constricts
What happens to the lens for far objects?
- suspensory ligaments contract
- cilliary muscles relax
- lens becomes flatter and there is less refraction of light
What happens to the lense for near objects?
- suspensory ligaments relax
- cilliary muscles contract
- lens becomes more thick and contracts and there is more light refraction
What is myopia?
- the lens is too curved/ the eyeball is too long
- this means the light refracts before the retina
- light is refracted too much
- can be fixed using concave lens