Chapter 14 part 1 Flashcards
Coordination: Neurones, Synapses
What is Coordination?
Coordination is the way all organs and systems of the body work efficiently together.
What is the Endocrine system?
The Endocrine system is where Coordination of chemicals takes place.
- The Endocrine system depends on the release of chemicals called hormones from Endocrine glands.
- Hormones are carried away by the bloodstream.
How does the Endocrine system work VS the nervous system?
The Endocrine system depends on the release of chemicals
Whereas the Nervous system works by sending electrical impulses along nerves.
What are Hormones?
Hormones are chemicals that are released by the endocrine glands and are carried by the bloodstream.
What does the CNS consist of?
The Central Nervous System consists of the Brain and Spinal cord.
What is the role of Nerves?
Nerves carry electrical impulses from the CNS to all parts of the body.
- This makes muscles contract or glands produce enzymes and hormones.
What are electrical impulses?
Electrical impulses are electrical signals that pass along nerve cells (Neurones)
*An impulse is a series of electrical pulses down a nerve fibre.
What is the PNS?
The PNS is the Peripheral Nervous system, which consists of nerves OUTSIDE the brain and spinal cord.
What are Effectors?
Effectors are glands and muscles that go into action when they receive nerve impulses or hormones.
Ex: bicep muscle flexes the arm; salivary gland produces saliva.
What are sensory impulses?
Sensory impulses are nerve impulses from sense organs (eyes, ear, nose) to the CNS.
What are Motor impulses?
Motor impulses are those nerve impulses that result in action from CNS to effectors.
What are Neurones/Nerve cells?
The CNS and PNS are made up of nerve cells called Neurones. There are 3 types, Motor, Sensory and Relay.
What are Motor Neurones?
These Neurones carry impulses from the CNS to the glands and muscles.
What are Sensory Neurones?
These Neurones carry impulses from Sense organs to the CNS.
What are Relay Neurones?
These Neurones are neither motor nor sensory. They connect neurones together.
Describe the structure of a Neurone:
A Neurone has a CELL BODY that consists of a Nucleus surrounded by a little Cytoplasm.
- From here there are branching fibres called DENDRITES. These make contact with other neurones.
- A long filament of Cytoplasm surrounded by an insulating sheath called a NERVE FIBRE, goes down the cell body.
*Nerve fibres run in the nerves.
What is a Nerve?
A Nerve is a white, tough and stringy that consists of hundreds of nerve fibres bundled together.
Nerves contain a mixture of sensory and motor fibres.
*Sensory fibres travel in 1 direction, motor in the opposite.
What is a Nerve Fibre?
A nerve fibre is the long filament of cytoplasm thats surrounded by an insulating sheath. This is part of a Neurone.
- It carries nerve impulses
How long is the fibre of a Nerve cell?
A nerve cell can have a fibre 1m long.
How long does a nerve pulse last?
Each pulse lasts 0.001 secs and travels at speeds up to 100 m s-1
What is the Reflex Arc?
The reflex Arc is simply where an action is produced. This is by impulses that cross synapses.
*It is the nervous pathway where involuntary reflexes take place.
What does the Reflex Arc contain?
A simple reflex arc contains a receptor,
sensory neurone, relay neurone, motor neurone and effector.
What is a Reflex Action?
A reflex action is an AUTOMATIC response to a STIMULUS.
It rapidly integrates and coordinates a stimulus with response of an effector. (muscles and glands) involuntarily.
What is a Stimulus?
A stimulus is a change in the external or internal environment of an organism.
What are the events in a simple reflex arc?
1) STIMULUS (tapping your kneecap)
2) RECEPTOR ( stretch receptor)
3) SENSORY NEURONE
4) COORDINATOR (Spinal cord)
5) MOTOR NEURONE
6) EFFECTOR (leg muscle)
7) RESPONSE (muscle contracts)
Explain what happens in the knee-jerk reflex:
- A stimulus (tapping) takes place at the kneecap.
- This stimulates the receptor (stretch receptor), which send off impulses in sensory fibers (sensory neurones) to the Spinal cord.
- The sensory fibre passes impulses across a synapse to a Motor neurone.
- The Motor neurone will conduct an impulse to the Effector (leg muscle).
- The muscle will now respond, contracting to the impulses.
What are the Functions of the spine?
- The spine is used in the Reflex arc to carry out Involuntary actions.
- Spine takes information from the Sensory Neurones and sends it to the brain.
- Spine takes impulses from the brain and sends it to Effectors (by Motor Neurones).
What is present in White and Gray matter?
- Gray matter consists of all cell bodies except for those in the Dorsal root Ganglia.
- White matter consists of nerve fibres.
What are the 2 roots of the spinal cord?
Dorsal root and Ventral root.
What is the dorsal root?
The Dorsal root is where all SENSORY FIBRES enter.
What is the Ventral root?
The Ventral root is where all MOTOR FIBRES leave.
What is a Ganglion(ganglia)?
A Ganglion is a bulge formed by all the cell bodies of sensory fibres in the Dorsal root.
What is a Synapse?
A synapse is a gap between 2 neurones.
What is the structure of a Synapse?
A Synapse has vesicles that contain neurotransmitter molecules, the synaptic gap and receptor proteins.
Describe the events at a Synapse
- When an impulse arrives:
- Vesicles in cytoplasm release Neurotransmitter substance.
- This substance quickly diffuses across the gap (Synaptic cleft).
- The substance binds with receptor molecules/proteins in the MEMRBANE OF THE NEURONE on the OTHER SIDE.
- This sets off an impulse in the Neurone.
How do Synapses control the direction of impulses?
- This is because Neurotransmitter substance is only synthesized on ONE SIDE of the synapse.
- Receptor molecules/proteins are only present on THE OTHER SIDE.
What is the function of Neurotransmitters?
Neurotransmitters are chemical messengers that carry chemical signals between 2 Neurones at a Synapse.
What is the function of Receptor molecules?
- Receptor molecules slow down the speed of NERVE IMPULSES to allow time for chemicals to diffuse across the Synaptic gap.
- Receptor molecules allow drugs to produce their effects in different parts of the body.
