Ch 14 - (Coordination & Response) Flashcards
What are the 2 components that the nervous system is made up of?
- Central nervous system (CNS)
- Peripheral nervous system (PNS)
Which organ does CNS involve?
Brain and spinal cord.
Which organ does PNS involve?
sensory and motor neurons.
What are electrical impulses?
electrical signals that pass along nerve cells (neuron)
What are glands and muscles called?
Effectors because they act when they receive nerve impulses or hormones.
Define sensory impulse.
Nerve impulses from the sense organ to the Central nervous system are called sensory impulses.
What is a nerve?
A bundle of neurons
What is a neuron?
Individual specialized cells that make up the nervous system
What are the 3 types of neurons?
- Motor neurons (effector neurons)
- Sensory neurons
- Relay neurons (connector or multipolar neurons)
what do motor neurons do?
carry impulses from CNS to effectors (muscles and glands).
what do sensory neurons do?
carry impulses from sense organs to CNS
What do relay neurons do?
they make connections to the sensory and motor neurons inside the CNS
Define synapses.
Junctions where neurons connect with each other
What parts does a neuron consist of?
- Cell body
- Dendrites
- Nerve fibre
Give a description of cell body as a part of a neuron.
Consists of a nucleus surrounded by cytoplasm
Give a description of dendrites as a part of a neuron.
Fibers, which branch from the cell body to make contact with other neurones.
Give a description of a nerve fibre as a part of a neuron.
a long filament of cytoplasm surrounded by an insulating sheath runs from the cell body of a neurone.
why do nerves contain a mixture of sensory and motor fibres?
So it can carry many different impulses.
Which direction do sensory and motor nerves travel in?
Sensory travel in one direction and motor travel in the opposite direction.
What is the structure of sensory neuron?
- Long
- has a cell body in the center of the axon
What is the structure of relay neuron?
- Short
- very small with a short axon
What is the structure of motor neuron?
- long
- has a large cell body at the top of the cell. This is where impulses start
what is the axon insulated by?
- Fatty sheath with a small with an uninsulated section called (nodes)
- Electrics, impulses jump from one node to another
Describe the process about what happens when an electrical impulse arrives at synapses.
- Impulse arrives at the end of Presynaptic neuron.
- Vesicles move towards, and fuse with Presynaptic membrane. This releases neurotransmitters into the synaptic cleft
- The neurotransmitters diffuse across the synaptic cleft down q concentration gradient
- Neurotransmitters attach to receptors on the postsynaptic membrane
- Triggers an impulse which travels along the postsynaptic neuron
- Transmitters are recycled or destroyed when an impulse is sent.
Why are neuro transmitters destroyed?
To prevent continued stimulation
What is the specialty of synapses?
only place where drugs can act of affect the nervous system
Define reflex action.
A means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)
What is a voluntary response?
Make a conscious decision so it starts with the brain
what is an involuntary response?
does not involve brain as the coordinator
What are some pointers about reflex responses?
- does not involve the brain
- automatic and rapid response
- quicker
- minimizes damage of the body
Describe how an impulse is sent when a pin is detected by the foot.
- The pin (stimulus) is detected by a pain/pressure/touch receptor is the skills.
- Sensory neurons send electrical impulses to the spinal cord (coordinator)
- Electrical impulses is passed onto relay neuron in spinal cord
- Relay neurons connect to motor neurons and pass the impulse on
- Motor neurone carries impulses to a muscle in the leg
- Muscle contracts and pulls fit up from sharp object
What is the reflex pathway?
- Stimulus (tapping the tendon below the kneecap)
- Receptor (stretch receptor)
- Sensory neuron
- Relay neuron: Coordinator (spinal cord)
- Motor neuron
- Effector
- Response
Define sense organs.
A group of receptor cells responding to specific stimuli such as light, sound, touch, temperature and chemicals.
What do receptor cells do?
Detect a change in the environment and stimulate electrical impulses in response.
What is skin sensitive to?
- Pressure
- Temperature (Hot, cold)
- pain
Sense: Touch and temperature
What is tongue sensitive to?
- chemicals in foods and drinks
Sense: Taste
What is nose sensitive to?
- chemicals in the air
Sense: Smell
What is ear sensitive to?
- sound and movement
Sense: Hearing & balance
What is eye sensitive to?
- light
Sense: Sight
Describe the process of when the receptor cell in the sense organ has been stimulated.
- It generates an electrical impulse
- Passed on to sensory neuron which carries impulse to CNS
- Response is decided and impulse is passed on to motor neurone (via a relay neurone)
- Motor neuron carries impulse ro effector
- Effector carries out the response.
Define eye.
Sense organ containing receptor cells that are sensitive to light (rod cells) and color (cone cells)
What is the function of cornea?
Transparent lens that refracts (bends) light as it enters the eye.
- refracts light and helps to focus it
What is the function of iris?
- colored ring of circular and radial muscles
- controls how much light enters the pupils.
What is the function of the lens?
- Transparent disc that can change shape to focus light onto the retina.
- refracts light to focus it onto the retina
What is the function of retina?
contains light receptor cells - rods (detect light intensity) and cones (detector colours)
- detects different colours
What is the function of optic nerves?
sensory neuron that carries impulses from retina to the brain
What is the function of pupil?
hole that allows light to enter the eye