B10 Flashcards
What is Homeostatis?
The maintenance of a constant internal enviroment
What do cells need to be to function?
They need to be homeostatis meaning they need to be optimum conditions in order to function.
What is homeostatis needed for?
For enzyme action and cell function
In the human body what does homeostatis control?
- Blood glucose concentration
- Body temperature
- Water levels.
What is involved in automatic control sytems?
Nervous and hormonal communication
What do Receptors do?
They are cells that detect the stimuli and the changes in the enviroment
What do coordination centres do?
Process the information received from the receptors eg brain,spinal cord and pancreas
What do effectors (muscle and glands )do?
They bring out responses which restore optimum level
What is the nervous system?
The nervous system enables humans to react to the surroundings and coordinate their behaviour
What do Receptor cells do?
Convert stimulus into electrical impulses.
What do electrical impulses do?
Travels along the sensory neurones to the CNS
What does the CNS do?
The information is processed and a response is coordinated. Resulting the electrical impulses being sent through motor neurones to effectors
What is the order of the CNS?
Stimulus —> receptor —> SN —> CNS —> MN —> effector —> response
What does the Sensory Neurone do?
they are neurones that Carry information as electrical impulses from the receptor to CNS
What does the Motor Neurone do?
The Neurons that carry carry electrical impulses from CNS to effectors
What are effectors?
All your muscles and glands which respond to nervous impulses
What can receptors and effectors form?
Part of Complex organs
What do effectors respond to?
They respond to nervous impulses and bring out a change
Give an example of a stimuli? (Bird)
When a bird sees a cat walking towards it
Give an example of a receptor and sensory neurone ? (Bird)
The receptor in birds eye gets stimulated . Sensory Neurone carrys information from receptor to CNS
Give an example of what the CNS does?
The CNS sends information to the muscles (effectors) of the bird wings along with motor neurones. The muscles contract and fly away.
What connects Neurones?
Synapses
What is the connection between two neurones called?
Synapse
How are nerve signals transfered?
Nerve signals are transfered by chemicals which diffuse across the gap.
What happens in the next neurone?
The chemicals send a new electrical signal
What helps prevent injuries?
Reflexes
What are reflexes?
Rapid automatic responses to certain stimuli that don’t involve the conscious part of the brain
What happens if someones shines a bright light in your eye?
Your pupils get smaller so less light is in and your eyes dont get damaged
What is the passage information in a reflex called?
Reflex arc
What does the reflex arc go through?
The CNS
What do the neurones in the reflex arc go through?
Spinal cord or unconscious part of the brain
What happens when a stimuli detects receptors?
Impluses are sent to the sensory neurone to a relay neurone in CNS
What do relay neurones do?
Connect sensory neurones to motor neurones
What happens when the impulses reach a synapse between sensory neurone and relay neurone?
They trigger chemicals to be released
What do the impulses travel along?
Motor neurone to the effector
What is reaction time?
The time it takes to repsond to a stimuli
What is the brain responsible for?
Complex behaviours
What is the brain apart of?
The CNS
What is the brain made up of?
Billions of interconnected neurones
What does the brain control?
Everything. Eg running , sleeping , breathing
What is the cerbal cortex?
Its the outer wrinkly bit and responsible for intelligence,memory and language
What is the medulla?
Controls unconscious activities. eg breathing
What is the cerebellum
Responsible for muscle coordination
What are the 3 ways scientists study the brain?
MRI scan, studing patients with brain damage, electrically stimulating the brain
What is an MRI scan?
It’s a tube-like machine that can produce detailed images of the brains structure. They use it in active places of the brain
What happens when electrically stimulating the brain?
It can be electrically stimulated by pushing a tiny electrode into the tissue and giving it a small zap of electricity
What can electrical stimulation reduce?
Muscle tremors
What does the Scelera do?
Its the supporting wall of the eye
What’s the cornea?
Transparent outter layer found at the front of the eye. It bends light into the eye
Whats the iris?
Contains muscles that allow it to control the diameter of the pupil and therefore controls how much light eneter the eye
What is the lens?
Focuses light onto the retina ( which contains receptor)
What is the shape of the lens comtrolled by?
Cilliary muscles and suspensory ligaments
What does the optic nerve do?
Carry receptors from retina to brain
How does the eye focus light on the retina?
By changing the shape of the lens (accommodation)
What happens when you look at close objects?
1) Cilliary muscles contract which slackens the suspensory ligaments
2) The lens becomes fat
3) This increases the amount of which it refracts
What happens at distant objects?
1) The cilliary muscles relax which allows suspensory ligaments to pull tight
2) This makes lens go thin
3) So it refracts by a smaller amount
What happens if the lens cannot refract?
The person will be short/long sighted
Why are people long sighted?
- The lens is the wrong shape and doesnt refract the light enough
- Eyeball is too short
The image of near objects are brought into focus behind the retina
How can you fix longsighted people?
Use a convex lens. This refracts light so they focus on retina
Whats the medical term for long sightedness?
Hyperopia
Why are people short sighted?
- The lens is the wrong shape and refracts light too much
- Eyeball is too long
- The image is brought in front of the retina
How do you prevent short sightedness?
Use concave lens so light focuses on retina
What is the medical term for short sightedness?
Myopia
What are the alternatives for vision defects?
- Contact lenses
- laser eye surgery
- replacement lens surgery
What are contact lenses?
Thin lenses that sit on the surface of your eye and are shaped to compensate for the fault in focusing
Advantages for contact lenses?
- Lightweight and invisible
- You can use them in sports
Disadvantages of contact lenses?
- Uncomfortable
- Soft lens can cause eye infection
What is laser eye surgery?
A laser is used to vaporise the tissue changing the shape of the cornea.
What does slimming it down in laser surgery do?
Less powerful byt improves short sight
What does changing the shape is laser eye surgery do?
More powerful and improve long sight
Disadvantage of laser eye surgery?
Can make eyesight worse than before
And cause infection
Whats the retina?
A layer of cells at the back of the eye that detect light and send signals to the brain through the optic nerve
