Topic 5 - Homeostasis and response (1) Flashcards
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What is homeostasis?
The process of maintaining a stable internal environment (regulating the conditions inside of you body + cells)
- in response to changes in both internal and external conditions
Why must conditions in your body be kept steady even when the external environment changes?
maintains optimum conditions for enzyme action and all cell functions
What is the definition of 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 three factors does homeostasis maintain?
- blood glucose concentration
- body temperature
- water levels
What regulates your constant internal environment?
What are two types of these?
- automatic control systems
- nervous responses /communication or chemical (hormonal) responses/ communication
What are the three main components of your automatic control systems?
- receptors
- coordination centres (including the brain, spinal cord and pancreas)
- effectors
What are receptors?
cells which detects stimuli (changes in the environment)
What are coordination centres?
- such as the brain, spinal cord and pancreas
- they recieve and process information from the receptors
What are effectors?
muscles or lands which bring about responses which restore optimum levels
What is the name of the mechanism used by your automatic control systems to keep your internal environment stable?
negative feedback
What is a stimulus?
A change in the environment
Explain when your body uses negative feedback?
When the level of something (e.g. water or temperature) gets too high or low
your body uses negative feedback to bring it back to normal
- this process is automatic (it happens without you even thinking about it)
What does a nervous system enable humans to do?
react to their surroundings and coordinate their behaviour
What are the 4 main parts of the human nervous system?
- central nervous system (CNS)
- sensory neurones
- motor neurones
- effectors
What is the central nervous system?
- In vertibrates this consists of the brain and spinal cord only
- In mammals, the CNS is connected to the body by sensory and motor neurones
What is the function of the central nervous system (CNS)?
The CNS is a coordination centre
recieves information from receptors and coordinates a response carried out by the effectors
these may be muscles contracting or glands secreting hormones
What are sensory neurones?
the neurones that carry information as electrical impulses from receptors to the CNS
What are motor neurones?
neurones that carry electrcal impulses from the CNS to the effectors
What are effectors?
All you muscles and glands, which respons to nervous impulses
What are receptors?
cells that detect stimuli
- there are many diiferent types of receptors (taste receptors on the tongueand sound receptors in the ears)
REMEMBER:
Receptors and Effectors can form part of complex organs
Give an example of a receptor forming part of a larger, complex organ?
the retina of the eye is covered in light receptor cells
What it the function of effectors?
they respond to nervous impulses and bring about a change
What are muscles and glands examples of and how do they each respond to nervous impulses?
- muscles and glands are known as effectors
- muscles contract
- gmands secrete hormones
What is a synapse?
the connection between two neurones
What is the connection between two neurones called?
a synapse
How do synapses connect neurones?
- the nerve signal is transferred by chemicals which diffuse across the gap
- these chemicals then set off a new electrical signal in the next neurone
What are reflexes and how are they useful to humans?
- they are rapid, automatic responses to certain stimuli that don’t involve a concious part of the brain
- they can reduce the chances of being injured
REFLEXES HELP TO PREVENT INJURY:
Explain what reflex action would take place if someone shines a bright light in your eyes?
your pupils automatically get smaller so that less light gets into the eye
this stops them getting damaged
REFLEXES HELP TO PREVENT INJURY:
Explain the reflex action that would take place if you get a shock?
- your body releases the hormone adrenaline automatically
- it doesn’t wait for you to decide that you’re shocked
What is a reflex arc?
The passage of information in a reflex (from receptor to effector)
What it the passage of information in a reflex called?
a reflex arc
REFLEX ARCS GO THROUGH THE CNS:
Where do the neurones in reflex arcs go through?
the spinal cord or an unconcious part of the brain
REFLEX ARCS GO THROUGH THE CNS:
What happens when a stimulus (e.g. a bee sting) is detected?
impulses are sent along a sensory neurone to a relay neurone in the CNS
REFLEX ARCS GO THROUGH THE CNS:
What happens when the impulses reach a synapse between the sensory neurone and the relay neurone?
- they trigger chemicals to be released
- these chemicals cause impulses to be sent along the relay neurone
REFLEX ARCS GO THROUGH THE CNS:
What happens when the impulses reach a synapse between the relay neurone and motor neurone?
Chemicals are released and cause impulses to be sent along the motor neurone
REFLEX ARCS GO THROUGH THE CNS:
What do relay neurones do?
connect sensory neurones to motor neurones
REFLEX ARCS GO THROUGH THE CNS:
What happens after the impulses are sent along the motor neurone?
impulses travel along the motor neurone to the effector (which is usually a muscle)
- the muscle will then contract
Why are reflex actions quicker than normal responses?
you don’t have to think about the response (which takes time)
