Chapter 12 - Coordination and Response (not done) Flashcards
Define stimuli
change in the environment that can be detected by organisms
Define receptors
cells or groups of cells that can detect stimuli
Define effectors
parts of the body that respond to a stimulus (e.g. muscles and glands)
Define coordination
the way that receptors detect stimuli and pass information to receptors
What are the 2 methods in which animals pass on information?
nerves and hormones
Define nerves
fastest method to transport transformation, part of the nervous system
Define hormones
slower method to transport information but still important. these chemicals are part of the endocrine system
Define neuron
specialised cells in the human body that conduct electrical impulses quickly
How many types of neurons are there in the body?
several
Define motor neuron
a type of neuron that transmits electrical impulses from the central nervous system to an effector
Are neurons typically long or short?
long
Complete the sentence:
Neurons have thin fibres of cytoplasm that…
stretch out from cell body
What is the longest fibre in the body?
axon
What is the shortest fibre in the body?
dendrites
What is the function of dendrites?
to pick up electrical signals called nerve impulses from other neurons nearby
What part of the neuron is the following sentence describing?
Some nerve fibres of active animals are wrapped in a layer of fat and protein
myelin sheath
What is the function of myelin sheath?
to insulate the nerve fibres so they can carry signals even faster
What 2 types of nervous systems do mammals have?
central nervous system (CNS) and peripheral nervous system (PNS)
What makes up the central nervous system?
brain and spinal cord
What makes up the peripheral nervous system?
other nerves in body
What is the main function of CNS?
to coordinate the electrical impulses travelling through the nervous system
What are the 3 characteristics of the PNS?
- made up of nerves that spread out from CNS
- each nerve contains hundreds of neurons
- includes receptors in our sense organs
What is meant by the term ‘CNS’?
central nervous system
What is meant by the term ‘PNS’?
peripheral nervous system
Are reflexes considered reactions?
yes
Define reflex arcs and explain where the pass through
the pathway along which an electrical impulse is passed (receptor → sensory neurone → relay neurones → motor neuron → effector)
What is meant by ‘reflexes are involuntary’?
it means that for a reflex to happen, we don’t have to think about them
Name one thing that is useful about reflexes
they are fast but our brains are still made aware of them.
What happens when a hand touches a hot plate
nerve impulse from motor neuron makes the muscle contract
Explain the reflex arc of a hand touching a hot plate
1) hand touches hot plate
2) sensory receptor in hand detects hot stimulus
3) the receptor starts of an electrical impulse
4) electrical impulse travels to the spinal chord along the axon from the receptor cell
5) this is called a sensory neuron because it’s carrying an impulse from a sensory receptor
6) in the spinal, neuron passes impulse to several other neurons. these are called relay neurons because they pass the impulse on
7) relay neurons pass the impulse to the brain, as well as a motor neuron that will pass it on to an effector
8) impulse passes down axon of a motor neuron to arrive at effector
9) arm muscle contracts
10) hand is pulled away
Give 3 information about the sensory neuron regarding the dendrites, the axons and nervous system
long dendrites, short axons, take info from our senses to CNS
Give 3 information about the relay neuron regarding the dendrites, the axons and nervous system
short dendrites, no axons, only in eyes, brain and spinal cord
Give 3 information about the motor neuron regarding the dendrites, the axons and nervous system
short dendrites, long axons, carry impulses away from CNS towards PNS
Define synapse
a junction between 2 neurons
What does a nerve impulse have to do to be passed from one neuron to the next?
it needs to cross a synaptic gap (a tiny gap between 2 neurons at a synapse)
What is there inside the axon of a neuron?
hundreds of tiny vesicles (tiny vacuole)
What do vesicles contain?
neurotransmitters
Define neurotransmitters
chemical molecules that diffuse across the synaptic gap to set up an electrical impulse for the next neuron
Explain synaptic transmission
1) electrical impulse travels along axon
2) causes movement of vesicles towards cell membrane
3) merge with cell membrane & release neurotransmitters (NT’s) into synapse
4) NT’s diffuse across gap
5) NT’s attach to receptors on next neuron (complementary shape)
6) binding triggers impulse to begin in that neuron
In how many directions does synaptic transmission happen?
only one
Define sense organs
a group of receptor cells that can respond to a specific stimulus using 5 senses
