Biology B5 (Homeostasis and Response part 1)

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What is homeostasis?
The regulation of the internal conditions of a cell or organism
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What does homeostasis maintain?
Optimal condtions for fucntion in response to internal/external changes, enzyme action and all cell functions
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In the human body, what 3 things include control of?
blood glucose concentration, body temperature, water levels
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What 2 types of responses may automatic control systems involve?
nervous or chemical
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What 3 things do all control systems include?
receptors, coordination centres, effectors
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What are receptors and what do they do?
They are cells which detect stimuli?
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What is a stimuli?
A change in the environment
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What are 3 places in the body that are coordination centres?
brain, spinal cord, pancreas
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What is the role of a coordination centre?
To receive and process information from receptors
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What 2 things could effectors be?
muscles or glands
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What is the role of an effector?
To bring about response to restore optimum levels
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What does the nervous system enable humans to do?
To react to their surroundings and to coordinate their behaviour
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What does information from receptors pass along?
cells (neurones)
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What is the form of this information?
An electricla impulse
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Where does this information go to?
the central nervous system (CNS)
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What is the CNS (2 areas)?
The brain and spinal cord
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What does the CNS then do?
coordinates the response of effectors
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If the effector was a muscle, what may be the response?
The muscle contracting
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If the effector was a gland, what may be the response?
The gland secreting hormones
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What is the order of the human nervous system?
stimulus, receptor, coordinator, effector, response
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What are the different types of neurons that work together in a reflex action?
sensory, relay, motor
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What type of response is a reflex action?
automatic and rapid
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Why is a reflex action much quicker than a general action?
It doesn't involve the conscious part of the brain
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Why are reflex actions needed?
To minimise damage to the body like touching something hot
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What is the sequence for a reflex action?
stimulus, receptor. sensory neurone, relay neurone motor neurone, effector, response
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What is the nerve pathway followed by a reflex action called?
A reflex arc
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What is the function of the sensory neurone?
To send electrical impulses to the relay neurone
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Where is the relay neurone located?
In the spinal cord
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What is the function of the relay neurone?
To connect sensory neurones to motor neurones
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What is the function of the motor neurone?
To send electrical impulses to an effector
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What does the effector produce?
A response
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What is the small gap where 2 neurones meet called?
A synapse
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What does an electrical impulse travel along?
An axon
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If the nerve is ending of a neurone, what is triggered?
Chemical messengers
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What are these chemical messengers called?
Neurotransmitters
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What do these neurotransmitters then do?
They diffuse across the synapse and bind with receptor molecules on the membrane of the second neurone
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What do the receptor molecules on the second neurone bind only to?
The specific neurotransmitters released from the first neurone
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What does this then stimulate?
The second neurone to transmit the electrical impulse
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What is the brain made of?
billions of interconnected neurones
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What are the 4 main parts of the brain?
The cerebral cortex, cerebellum, medulla, hypothalamus
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What is the function of the cerebral cortex?
To control intelligence, conscious thought, personality and high-level functions such as language and verbal memory
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What is the function of the cerebellum?
To control balance, co-ordination of movement and muscular activity
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What is the function of the medulla?
To control unconscious activities such as heart rate and breathing rate
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What is the function of the hypothalamus?
it is the regulating centre for temperature and water balance in the body
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What are the 7 parts of the eye?
retina, optic nerve, sclera, cornea, iris, ciliary muscles, suspensory ligaments
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define accommodation
the process of changing the shape of the lens to focus on near or distant objects
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What happens to the ciliary muscles and suspensory ligaments to focus on a near object?
CM contracts, SL loosen
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What happens to the lens?
It is then thicker and refracts light rays strongly
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What happens to the ciliary muscles and suspensory ligaments to focus on a distant object?
CM relaxes, SL are pulled tight
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What happens to the lens?
it is then pulled thin and only slightly refracts light rays
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What are the two common defects of the eyes?
Myopia and hyperopia
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What is myopia also known as?
Short-sightedness
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What is hypermyopia also known as?
Long-sightedness
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In both defects, what is the cause?
rays of light not focusing on the retina
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What can both defects generally be treated with?
spectacle lenses which refract the light rays so that they do focus on the retina
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What are examples of new technologies to also treat this?
Hard or soft contact lenses, laser surgery to change the shape of the cornea, a replacement lens in the eye
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What is body temperature monitored and controlled by?
The thermoregulatory centre
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Where is this located?
In the brain
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What does the thermoregulatoy centre contain?
receptors sensitive to the temperature of the blood
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Where else in the body can you find these temperature receptors?
skin
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What can the skin send to the thermoregulatory centre?
nervous impulses
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What happens if the body temp is too high?
Blood vessels dilate and sweat is produced from the sweat glands
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What do both of these mechanisms cause?
a transfer of energy from the skin to the environment
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What happens if the body temp is too low?
Blood vessels contract, sweating stops and skeletal muscles contract?
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What is it called where blood vessels dilate?
vasodilation
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What is it called where blood vessels contract?
vasoconstriction
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What is it called where skeletal muscles contract?
shivering
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Other cards in this set

Card 2

Front

What does homeostasis maintain?

Back

Optimal condtions for fucntion in response to internal/external changes, enzyme action and all cell functions

Card 3

Front

In the human body, what 3 things include control of?

Back

Preview of the front of card 3

Card 4

Front

What 2 types of responses may automatic control systems involve?

Back

Preview of the front of card 4

Card 5

Front

What 3 things do all control systems include?

Back

Preview of the front of card 5
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