15) Coordination and response Flashcards
Compare between nervous system and endocrine system
- Nervous system
-Speed of action: Faster
-Nature of message: Electrical impulses moving through neurons
-Duration of action: Rapid and short
-Area of response: localised
-Origin:
A) involuntary action: sense organs’ receptors
B) Voluntary: brain
2.Hormonal/endocrine
-Speed of action: slower
-Nature of message: Chemical messenger in blood
-Duration of action: slow and long
-Area of response: wide spread
-Origin: endocrine gland
Advantages of nervous system
-Reflex action
-Protects against mechanical injury
-Fast
-Automatic, involuntary
Advantages of endocrine system
- Lasts longer time
- Wide spread action
- Less energy because the hormones are carried in blood
Sense organs
Group of receptor cells, responding to a specific stimulus
Central nervous system consists of
1.Brain
2.Spinal cord
Peripheral nervous system
Sensory neurone: cell body not at end (middle), with no dendrites, short axon
Relay neurone: No myelin sheath, has dendrites and axon
Motor neuron: Dendrites, cell body at one end, has myelin sheath
Structure of neurone
1.Cell body: Nucleus, cytoplasm, mitochondria.
2.Dendrites: Pick up the electrical signals from near by neurones and sends them towards the cell body
3.Axon: Carries nerve impulse away from cell body
4.Myelin sheath: Made from fats and proteins acting as electrical insulator, to speed up electrical impulse transmission
5. Motor end plate
Describe how the structure of the neurone is related to its function
1.Transmit the nerve impulses over a long distance
2.Dendrites pick up the electrical signals from nearby neurone to cell body
3.Axon carries away the impulse from neurone
4.Mitochondria site of aerobic respiration to release energy for nerve impulse transmission
5.Myelin sheath, acts as electrical insulator
6.Vesicles release neurotransmitters across synapse
Describe the pathway taken by the reflex action to allow hand withdrawal upon touching a hot plate
- Heat from the hot plate acts as stimulus
- Stimulus is detected by temperature receptors in skin
3.A nerve impulse will be carried away by sensory neurone to CNS - Across synapse by diffusion of neurotransmitters
5.Relay neurones in CNS carry impulses to motor neurone
6.Motor neurone carries nerve impulse away from CNS to effector - Effector carries a response where muscles contract and pull hands away
Synapse
-Junction between two neurons where where nerve impulse is transmitted by diffusion of neurotransmitters
(needed to slow down nerve impulse transmission)
-ensures impulse moves in one direction
Why synapse acts as a one way valve
1.Neurotransmitters are produces on one side of the synapse so the impulse can only move from that side
2. Receptors are found on surface of second neurone
Explain how nerve impulse pass across the synapse
- When electrical impulse reaches end of neurone
2.Vesicles containing neurotransmitters to move to end of neurone and fuse with presynaptic membrane - Releases neurotransmitters
4.Which will diffuse across synaptic cleft
5.To bind to receptor protein on the post synaptic neurone - Trigging a nerve impulse in second neurone
Compare between voluntary action and involuntary action
1.Voluntary action
-Non automatic action
-Involves a conscious decision by brain
-slower
-starts in brain, ends in effector
- same stimulus show different response
2.Involuntary action:
-Automatic action
-Doesn’t involve a conscious brain decision
-Faster
-starts by stimulating the receptors in sense organs, ends in effector
- same stimulus leads to same response
Cornea
Refract most light
Transparent to allow passage of light
Aqueous humor
Watery fluid to support cornea
Iris/pupil
-Iris is a muscle, coloured part of the eye
- iris controls change of size of pupil to control amount of light reaching retina
Lens/Suspensory ligaments and ciliary muscles
-Lens refract light
-Suspensory ligaments and ciliary muscles change convexity of lens to allow accommodation
Sclera
Tough outer layer to protect eye against damage
Vitreous humor
Fluid, jelly like structure keeping eye ball in shape
Choroid
-Dark layer that causes the pupil to appear dark
-Contains blood vessels that nourish the cells of the retina with foods and oxygen
Retina
Contains the photoreceptors (rods and cones) that convert light into electrical impulses to be sent to the brain through optic nerve
Fovea
Contains the highest concentration of cones, for sharpest image
Blind spot
Exit point to optic nerve, no photoreceptors, so light falling on this part is not detected
Accommodation
It is the change of convexity of the lens to help focusing light on certain point on the retina, according to the distance of the object from eye
