Homeostasis Flashcards
What is the pathway an impulse takes through the nervous system?
stimulus –> receptors –> sensory neuron –> central nervous system –> motor neuron –> effectors –> response
How are nerve cells adapted to carry electrical impulses around the body?
- They are long to cover more distance
- They end in branches to make connections with other neurons
How does an impulse cross a synapse?
When the impulse reaches the end of a neuron, it triggers the release of neurotransmitters which diffuse across the synapse to the next neuron, creating an impulse
What is a reflex?
A fast, unconscious response to certain stimuli so that we don’t get injured
What is the reflex arc?
stimulus –> receptors –> sensory neuron –> relay neuron –> motor neuron –> effectors –> response
What is affected by the cerebral cortex?
Memory, consciousness, intelligence, language
What is affected by the hypothalamus?
Regulation of body temperature, sends signals to the pituitary gland
What is affected by the cerebellum?
Balance, muscle coordination
What is affected by the medulla?
Unconscious activities - breathing, heartbeat
How does an MRI work?
With magnetic fields and microwaves to produce an image of the brain’s structure
What can you do to see what part of the brain does something?
Stimulate the tissue with an electrical impulse
How does the eye adapt to bright light?
The circular muscle contracts, the radial muscles relax and this causes the pupil to constrict
How does the eye adapt to dim light?
The circular muscles relax, the radial muscles contract and this causes the pupil to dilate
How does the eye focus on a near object?
The ciliary muscles contract, the suspensory ligaments slacken, the lens thickens and strongly refracts the light
How does the eye focus on a distant object?
The ciliary muscles relax, the suspensory ligaments pull tight, the lens thins and weakly refracts the light
What is myopia and how is it fixed?
Short sightedness where the light is focused in front of the retina. It can be fixed with concave glasses
What is hyperopia and how is it fixed?
Long sightedness where the light is focused behind the retina. It can be fixed with convex glasses
Pros and cons of contact lenses
Pros:
- easy to acquire
- no surgery
Cons:
- expensive overtime
- soft lenses have a risk of infection
- sometimes uncomfortable to put in
Pros and cons of laser eye surgery
Pros:
- permanent fix
- less invasive than replacement lens surgery
Cons:
- expensive
- surgery is always risky
Pros and cons of replacement lens surgery
Pros:
- permanent fix
- can fix multiple conditions
Cons:
- expensive
- surgery is always risky
- more invasive surgery
What is a hormone?
Chemical messages made of protein that travel through the blood to a target organ
What hormones are produced in the pituitary gland and what do they do?
ADH - controls water concentration of the blood
FSH - causes an egg to mature in the ovaries
LH - causes an egg to be released
TSH - controls thyroxine levels
What hormones do the ovaries produce and what do they do?
Oestrogen - controls puberty in females and causes the uterus lining to thicken
Progesterone - maintains the lining of the womb during the menstrual cycle
What hormone do the testes produce and what does it do?
Testosterone - controls puberty in males