Homeostasis and Response Flashcards
(52 cards)
Define homeostasis
The maintenance of a constant internal environment (and maintain optimum conditions when there is internal or external change)
What is homeostasis useful for in the body?
Blood glucose concentration
Body temperature
Water levels
What do all control systems have?
Receptor
Co-ordination Centre
Effector
What is the nervous system useful for?
Reacting to surroundings and co-ordinating behaviour
In the nervous system what is ‘information’ transported as?
Electrical impulses
In the nervous system, where does the electrical impulse go? Start with ‘stimulus’
Stimulus
Receptor
Sensory Neurone
Central Nervous System
Motor Neurone
Effector
Define the motor neurone
The neurone that carries the impulse from the CNS to the effector
Define the sensory neurone
The neurone that carries the impulse from the receptor to the CNS
What is different about a reflex arc compared to the nervous system?
The impulse bypasses the brain
What is the CNS replaced with in a reflex arc
Relay neurone
What happens in a reflex arc when the impulse travels over the relay neurone and cannot go over the synapse?
Neurotransmitters diffuse across the synapse
Neurotransmitters bind to receptors on the motor neurone
The binding triggers the impulse to continue
How do depressants affect a reflex arc?
They slow the rate of diffusion of neurotransmitters and slow the reflex
What is the cerebral cortex for?
Intelligence and memories
What is the cerebellum for?
Vital part of the brain important for muscle control, movement and balance
What is the medulla?
It connects the brain stem and spinal cord, it controls unconscious but necessary processes like breathing and blood pressure
How can we study the human brain?
Monitoring behaviour
Electrically stimulating different parts of the brain
Using magnetic resonance imaging (MRI scans)
Define the following:
Pupil
Iris
Lens
Sclera
Cornea
Optic nerve
Retina
Suspensory Ligament and Ciliary Muscle
Allows light to enter the eye
Changes size to control amount of
light entering the eye
Focus light on one point on the retina
White outer protection
Refraction and Protection
Carries impulse to brain
Turns image into electrical impulse
Contratcs to change shape of lens
3 causes of myopia and hyperopia
Weak ciliary muscles
Lens is too thick can’t be changed
Irregular shaped eyeball
What happens in the eye when focusing on something close?
The muscles contract and ligaments loosen to make lens thicker
This means there is more refraction
The image is able to hit one point on the retina
What happens in the eye when focusing on something far away?
The muscles relax and ligaments contract to make lens thinner
Because the light is dispensing at a much smaller angle so needs less reaction
The image is able to hit one point on the retina
What is myopia and hyperopia
Short-sightedness and long-sightedness
What monitors and controls body temperature
Thermoregulatory centre in the brain
Describe what happens when there is a change in body temperature
Temperature receptors on skin and thermoregulatory centre detect change
Nervous impulse is sent to thermoregulatory centre
Thermoregulatory centre co-ordinates a response
Vasodilation (expand) and sweating if too hot
Vasoconstriction (constrict) and shivering if too cold
The endocrine system is composed of what?
Glands which secrete chemicals
called hormones directly into the bloodstream
