B10 Flashcards
Homeostasis
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.
Receptor
Detects changes in the environment
Effector
Muscles or glands that bring about responses
Stimulus
Change in the environment
Coordination centre
Receives, processes information and coordinates responses
How can the ACS communicate information
Through the nervous system and hormonal communication etc
ACS ORDER
Stimulus - receptor - control centre - effector - response
What makes up the CNS
Brain - spinal cord - neurones
Homeostasis controls internal conditions such as
body temperature, pH levels, water levels, co2 levels and blood glucose concentration
It’s important for maintaining optimum conditions for the enzyme action and all cell functions.
Synapse
electrical impulse arrives at the end of a neurone causing vesicles containing a chemical called a neurotransmitter to be released into the synapse.
The neurotransmitter diffuses across the synapse and binds to chemical receptors on the next neurone.
This causes an electrical impulse to be generated in the next neurone
Main stages of a reflex arc
Stimulus - receptor - sensory neurone - relay neurone - motor neurone - effector - response
How does the eye work
Light enters the eye Refracts through the cornea Refracts through the lens Lens changes thickness to focus light Image formed on the retina
Cornea
A curved transparent membrane at the front of the eye; most of the refraction takes place here.
Iris
The coloured part of the eye
Pupil
A hole where light passes through - can change in diameter
Lens
Flexible - focusses image on retina - ciliary muscles contract and therefore squashing the lens so that it can have a shorter focal length so it can see stuff closer
To focus on a near object
the ciliary muscles contract
the suspensory ligaments loosen
the lens is then thicker and refracts light rays strongly.
To focus on a distant object
Ciliary muscles relax
Suspensory ligaments get pulled tight
Lens is then pulled thin so little refraction of light occurs
Accommodation
Accommodation is the process of changing the shape of the lens to focus on near or distant objects.
What are the two common defects of the eye
Myopia and hyperopia
Hyperopia can be foxed with a _______ lens
Convex
Myopia can be foxed with a _______ lens
Concave
New technologies on fixing eyes are
Contact lenes Laser eye surgery to change the shape of cornea as it does most of the refracting Replacement lens (can risk damaging retina)
Medulla
Unconscious activities - breathing heart beat
Cerebral cortex
Conscious activities - memory language
Cerebellum
Muscle contraction and balance
Electrical stimulation
Because the nervous system communicates using electrical impulses, electrical stimulation is used to help treat conditions such as Parkinson’s disease (causes tremors)
MRI
have allowed us to learn which areas of the brain are active during different activities, such as moving, speaking and listening
Brain damage
By studying patients with brain damage, where part of their brain doesn’t function, neuroscientists have been able to link particular regions of the brain to particular functions.
