B3 Flashcards
(37 cards)
What do receptor cells do?
Detect the change in the environment and send this information as nervous impulses
Where are receptor cells found?
In the sense organ
Role of sensory, relay and motor neurones?
Carry the electrical impulses from the receptor cells to CNS
Carry the electrical impulses from CNS to effector
Carry the information from the sensory to motor neurones
What is an effector?
A response:
- glands secrete hormones
- muscles contract
What is a synapse?
The electrical impulses trigger a release of transmitter chemicals, which diffuse across the gap of two neurones and attach to the receptor molecules - setting off a new chemical impulse
Adaptions of neurones to speed transmission
- long neurones
- myelin sheath: insulator less energy wasted
How does the lens change to focus on nearby
objects
- lens becomes fatter (more convex)
- ciliary muscle contracts
How are images formed?
When light is focused on the retina, photoreceptors in the retina produce a nervous impulse that travels down the optic nerve, to the brain, where it is interpreted as a visual image
Cornea Pupil Iris Lens Ciliary body
C - protects the eye, refracts light
P - allows light to enter the eye
I - controls how much light enters the eye by contracting / relaxing
L - refracts light onto the retina
CB - controls lens shape, by contracting / relaxing
Short sightedness
- eyeball to long, lens too strong
- bends light too much
- light focuses in front of the retina
- concave
Long sightedness
- eyeball too small, lens to weak
- doesn’t refract light enough
- focus behind the retina
- convex
What are the types of receptor cells?
Rods
- dim light
Cones
- colours
Cerebrum Cerebellum Medulla Hypothalamus Pituitary gland
C - milc , consciousness, language, intelligence, memory
C - posture, balance
M - involuntary actions, breathing, heart rate
H - controls temperature and water levels, produces hormones that regulate the pituitary gland
P - stores and releases hormones
Damage to peripheral nervous system
Tissue can be regrafted over damaged tissue. Restoring neurone pathway.
What is it hard to repair the CNS?
Spinal cord - 1.5cm diameter
- 31 pair of nerves
Repairing damage is hard to do without damaging others
Treatments for CNS damage
Radiotherapy - brain tumour Surgery - replace damaged brain tissue Deep brain stimulation - inserting electrodes to stimulate brain function
What is the endocrine system?
Consists of glands that produce hormones
chemical messengers that regulate body functions
What is negative feedback?
- receptor detects a change in environment
- effectors work to reverse the change and restore original conditions
What is thyroxine?
Regulates the bodies metabolic rate
What is metabolic rate?
The speed at which the body transfers energy from its chemical store in order to carry out functions
How are thyroxine levels controlled?
The hypothalamus detects a change in environment and stimulates the pituitary gland to release TSH
TSH stimulates the thyroid gland to release more thyroxine
Thyroxine increases metabolic rate - cells have more energy
What effect does adrenaline have?
Respires faster - more ATP
Increases heart rate
Faster breathing
Diverts blood to muscles instead of kidneys
What controls the menstrual cycle?
FSH - matures the egg, stimulates oestrogen production
Oestrogen - inhibits FSH, stimulates LH production, thickens lining (4)
LH - release egg, ovulation, stimulates progesterone, inhibits oestrogen
Progesterone - maintains lining, inhibits LH, low FSH = high progesterone
What do oestrogen / progesterone tablets do?
Prevents implantation and ovulation
Thickens mucus
