homeostasis and response Flashcards
What is homeostasis?
Maintenance of a constant internal environment in order to maintain optimum conditions for enzymes and cellular function
Give examples of conditioned maintained by homeostasis in the body
blood glucose concentration
Body temperature
Water levels
What two types of responses are used in body control systems?
Nervous and chemical
What 3 components do all control systems have?
receptors
Coordination centres
effectors
what is the function of a receptor?
Receptors detect changes in the environment
What is the function of a coordination centre?
Coordination centres obtain and process information from receptors
what is the function of an effector
Bring about response to stimuli
What is the function of the nervous system?
The nervous system allows the body to react to its surroundings and coordinate an appropriate response
How does a stimulus lead to response being carried out by the body?
stimulus is converted into an electrical impulse by the receptors
The electrical impulse passes along century neurons to the central nervous system
The CNS coordinate an appropriate response and an electrical impulse is sent along motor neurons to the effector, which carries out the response 
what sequence of events describes how the nervous system works? 
stimulus——>receptor——->coordinator——>effector——>response
what is a reflex action?
A reflex action is an automatic and rapid response, which does not involve any conscious input from the brain
why are reflex actions important?
Reflex actions a survival by preventing harm to the body
describe how reflex action occurs via a reflex arc
The stimulus is detected by a receptor
An electrical impulse passes along a sensory neuron to the spinal cord
At a pace between a sensory neuron and a relay neuron, a chemical diffusers across the gap and stimulates a new impulse which passes along the relay neurone
The same process occurs at a centipedes between a relay neuron and motor neuron
At the effector an appropriate response is carried out
What is the difference between a reflex pathway and a conscious pathway?
Within a reflex pathway, the coordination centre is a relay neuron found in the spinal cord unconscious parts of the brain. In a conscious pathway, the coordination centre is the conscious part of the brain.
What is the function of the cerebral cortex?
Controls consciousness, intelligence, memory and language
What is the function of the cerebellum?
Controls muscular coordination
what is the function of the medulla
Controls unconscious activities, e.g. breathing, heart rate
why is the investigation and treatment of the brain difficult?
The brain is a complex and delicate organ
The brain is easily damaged and destroyed
Certain membranes prevent drugs from reaching the brain
The exact function of each part of the brain is not known
what methods are used by scientists determine brain function?
Studying patients with brain damage
Electrical stimulation of the brain
MRI scans
what stimuli are the receptors of the is sensitive to?
Light intensity and colour
What are the two main functions of structures found within the eye?
focusing on near or distant objects
Adaptation to dim light
describe the structure and function of the retina
The retina is a light sensitive layer found at the back of the eye
light stimulates the retinal cells, resulting in impulses being sent to the brain 
describe the structure and function of the optic nerve
The optic nerve connects the eye and the brain
It carries impulses to the brain so that an image can be visualised
describe structure and function of the sclera
the sclera is the tough outer layer of the eye which protects its internal structures