B5-Homeostasis and response Flashcards
Define Homeostasis
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes
What does homeostasis in the human body control?
- Blood glucose concentration
- Body temperatures
- Water levels
What are the 3 features in a control system?
- Receptors
- Coordination centres
- Affectors
What are receptors?
Cells that detect changes in the internal or external environment known as stimuli
What is the function of coordination centres?
To recieve and process information from receptors around the body
What do effectors do?
Muscles or glands that bring about responses, which restore optimum levels
What 2 type of responses may occur during homeostasis?
- Nervous responses-nervous system
- Chemical responses-endocrine system
What does the central nervous system (CNS) consist of?
The brain and spinal cord
What is the part of nervous system that isn’t the CNS called?
The peripheral nervous system
Describe the way the nervous system works (5)
- Sensory receptor detects a stimuli
- Sensory neurons carry the electrical impulse to the CNS
- The electrical impulse is carried through the CNS through relay neurons
- The electrical impulse is carried by motor neurons after it leaves the CNS
- The electrical impulse reaches the effector
Give the sense organ for the following:
* Touch, temperature and pain
* Chemicals (in food and drink)
* Chemicals (in air)
* Light
* Sound and position of head
- Skin
- Tongue
- Nose
- Eye
- Ear
What are 2 specialised features of a neuron (nerve cell) and explain them?
- Axon-a long fibre which is insulated by a fatty myelin sheath-long so they can carry electrical messages up and down the body
- Dendron-Tiny branches which branch further as dendrites at each end-these recieve incoming impulses from other neurones
What are reflex actions?
Actions that are automatic and rapid and don’t involve the brain
Why are reflex actions necessary?
- By providing an automatic and rapid response to a stimulus this minimises any damage to the body from potentially harmful conditions.
- They also are reflexes that take care of your basic body functions such as breathing and digesting food
What does a reflex action not involve?
The conscious part of the brain
What are the stages of a reflex arc?
1) A receptor in the skin detects a stimulus
2) Sensory neurone sends electrical impulses to relay neurone, which are located in the spinal cord
3) Motor neurone sends electrial impulses to an effector
4) Effector produces a response
This whole pathway is a reflex arc
What are gaps between neurones called?
Synapses
What are synapses?
Gaps between nerves in which chemical messangers (neurotransmitters) diffuse across the synapse and bind with the receptor molecules on the membrane of the second neurone-this causes a second electrical imulse to be produced.
Fill in the gaps:
The receptor molecule on the second neurone bind only to the …………… neurotransmitters.
Specific
True of False:
An impulse also travels up the spinal cord to the concious areas of the brain
True-this happens so that you know about the reflex action
How do you carry out an investigation into the effect of a factor in human reaction times?
1)Person A holds their hands with a gap between their thumb and first finger
2)Person B holds the ruler with the sero at the top of person A’s thumb
3)Person B drops the ruler without telling person A who must catch it
4)The number lebel with the top of person A’s thumb is recorded in a suitable table
5)This experiment can be repeated with external factors such as noise
What are the 4 main areas of the brain?
- The cerebrum (outer layer called cerebral cortex)
- The cerebellum
- The medulla (oblongata)
- The hypothalamus
What does the cerebrum (cerebral cortex do)?
It controls intelligence, counsciosness, personality, memory and language
What does the cerebellum do?
It coordinates muscular activity, movement and balance
What does the medulla oblongata do?
It controls unconscious activities such as heart rate and breathing rate and gut movements
What does the hypothalamus do?
It is the regulating centre for temperature and water balance within the body
What is tough, white outer area of the eye called?
The sclera
What is the transparent region at the front of the sclera?
The cornea
What does the iris do?
It controls the size of the pupil and the amount of light entering the light
What do the ciliary muscles do?
They change the shape of the lens to focus light onto the retina
What carries impulses from the eyes to the brain?
The optic nerve
What is accommodation?
The process of changing the shape of the lens to focus on near or distant objects
How do we focus on close up objects?
By contracting the ciliary muscles loosening the suspensory ligaments