Coordination and Response Details Flashcards
Electrical impulses travel along…
neurons
Parts of the mammalian nervous system
-Central nervous system(CNS)
-Peripheral nervous system(PNS)
Components of the central nervous system(CNS)
-Brain
-Spinal cord
Components of the peripheral nervous system(PNS)
Nerves(outside of the brain and spinal cord)
Role of the nervous system
Coordination and regulation of body functions
Components of a simple reflex arc(in order)
Receptor → Sensory neuron → Relay neuron → Motor neuron → Effector
Function of a synapse
Ensures the single direction of the transmission of neurons
Structure of a synapse
-Presence of vesicles containing neurotransmitter molecules
-Synaptic gap
-Presence of receptor proteins
Events at the synapse
-An impulse stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap
-The neurotransmitter molecules diffuse across the gap
-Neurotransmitter molecules bind with receptor proteins on the next neuron
-An impulse is then stimulated in the next neuron
Function of cornea
Refracts light
Function of iris
Controls how much light enters the pupil
Function of lens
Focuses light unto the retina
Function of retina
Contains light receptors called rods(responsible for night vision) and cones(responsible for colour vision)
Function of optic nerve
Carries impulses to the brain
Features of fovea
-Area of the retina
-Where most of the light is focused on
-Has a highest density of cones
Function of rods
Greater sensitivity to light for night vision
Function of cones
Absorbing light of different colours for colour vision
Role of the pupil reflex
Appropriately controls the level of light that enters the eye
In bright conditions, pupils become…
smaller
In dim conditions, pupils become…
larger
Nature of the movement of circular and radial muscles in the iris
Antagonistic
What happens to the pupil in bright light(regarding circular and radial muscles)
-Circular muscles contract
-Radial muscles relax
-Pupil becomes constricted(smaller)
What happens to the pupil in dim light(regarding circular and radial muscles)
-Circular muscles relax
-Radial muscles contract
-Pupil becomes dilated(bigger)
What the ciliary muscles and suspensory ligaments do when the eye is looking at a distant object
-Ciliary muscles relax
-This allows suspensory ligaments to tightly pull on each side of the lens(contract)
-Lens becomes stretched and thin(becomes less powerful and hence bends light less)
What the ciliary muscles and suspensory ligaments do when the eye is looking at a near object
-Ciliary muscles contract
-This allows suspensory ligaments to slacken
-Lens becomes thicker(becomes more powerful and hence bends light more)
Amount of effort it takes for the lens to focus light rays from a distant object
Less effort(than with nearby objects)
NB: this is because the light rays are parallel
Amount of effort it takes for the lens to focus light rays from a nearby object
More effort(than with distant objects)
NB: this is because light rays are divergent
Where adrenaline is produced
Adrenal gland
Where insulin is produced
Pancreas
Where testosterone is produced
Testes
Where estrogen is produced
Ovaries
Effects of adrenaline
-Increased breathing rate
-Increased heart rate
-Increased pupil diameter
-Increased blood glucose concentration
Features of hormonal control
-Chemical transmission
-Transport of hormones in blood
-Slow speeds of transmission(takes more time to take effect)
-Long-term effect
Features of nervous control
-Electrical transmission
-Transport of electrical impulses through neurons(nervous system)
-Fast speeds(quickly takes effect)
-Short-term effect
Where glucagon is produced
Pancreas
Reflex arc(involuntary action)
Sensory receptor → Sensory neuron → Motor neuron → Effector
Role of insulin
Decreases blood glucose concentration(by causing liver to convert glucose into glycogen for storage inside liver cells)
Role of glucagon
Increases blood glucose concentration(by causing liver to convert glycogen into glucose and release it into the blood)
Role of negative feedback
Reduces the levels of substances or conditions in the body back to a set point(due to them becoming too high)
Role of positive feedback
Increases the levels of substances or conditions in the body to a set point(when they get too low)
What happens when blood sugar levels are too high
-Pancreas secretes insulin
-Liver converts blood glucose to glycogen
-Blood sugar levels fall
What happens when blood sugar levels are too low
-Pancreas stops insulin secretion
-Pancreas secretes glucagon instead
-Liver converts glycogen to glucose
-Blood sugar levels rise
Cause of type 1 diabetes
Insufficient insulin production(which leads to very high glucose levels)
Symptoms of type 1 diabetes
-Increased hunger
-Frequent urination
-Blurred vision
-Tiredness and fatigue
-Unexplained weight loss
Treatment of type 1 diabetes
-Controlling sugar intake
-Monitoring sugar levels
-Insulin injections
Optimum body temperature
37°C
Role of basic insulation(as a mechanism to retain heat)
-Fat layer in skin acts as an insulator
-Skin hair follicles stand up to trap a layer of air around the skin which also acts as an insulator
Role of shivering
Helps to retain heat(increased metabolism in muscles increase heat circulation)
Process of vasoconstriction
-Heat is carried in the blood
-If blood goes near the skin surface, then blood radiates out of the body
-Constriction of the blood arterioles reduce the amount of blood flowing near the skin surface to retain heat in the blood
Role of sweating
Helps to lose heat(as water evaporates from sweat which causes the skin and body to cool down)
Sweat is a mixture of…
water, salt and urea
Process of vasodilation
-Dilation of skin arterioles
-Increase in the amount of blood flowing near the skin surface to allow more heat to radiate out of the body
Phototropism and gravitropism are examples of….
the chemical control of plant growth
Role of auxins
Change the rate of elongation in plant cells and control the growth of stems and roots
Role of auxin in controlling shoot growth
-Auxin is made in the shoot tip
-Auxin diffuses through the plant from the shoot tip
-Auxin is unequally distributed in response to light and gravity
-Auxin stimulates cell elongation
What auxins do in the shoots
Promote plant growth
What auxins do in the roots
Inhibit plant growth
