Co-ordination And Response Flashcards
What are the two communication systems in mammals
Nervous system
Endocrine system
What are physiological factors controlled by homeostasis in mammals
Core body temp
Metabolic waste
Blood pH
Concentration of glucose in blood
Water potential of blood
Concentration of respiratory gases
What is homeostasis
the control or regulation of the internal conditions of a cell or organism
What are some cooling mechanisms in humans?
- Vasodilation of skin capillaries
- Sweating
- Flattening of hairs
What are some Warming mechanisms in humans
- Vasoconstriction of skin capillaries
- Shivering
- Erection of hairs
SHOOTS - Phototropic/geotropic
As shoots grow upwards, away from gravity and towards light (so that leaves are able to absorb sunlight), shoots show a positive phototropic response and a negative geotropic response
ROOTS - Phototropic/geotropic
As roots grow downwards into the soil, away from light and towards gravity (in order to anchor the plant and absorb water and minerals from the soil), roots show a negative phototropic response and a positive geotropic response
What are auxins?
plant growth regulator that coordinate and control directional growth responses such as phototropisms and geotropisms
Where are auxins produced?
produced in the tips of the shoots and the roots
What effect do auxins have in shoots?
auxins promote cell elongation (growth); more auxin = more cell elongation = more growth
What effect do auxins have in roots?
auxins inhibit cell elongation (growth); more auxin = less cell elongation = less growth
How is the distribution of auxins determined?
If a shoot or root is placed on its side, auxins will accumulate along the lower side as a result of gravity; so the uppermost side has a lower auxin concentration
In the shoots, the lower side grows faster than upper side, so the shoot grows upwards
In the roots, the lower side grows slower than the upper side, so the root grows downwards
How do auxins work?
Auxin is mostly made in the tips of growing shoots and then diffuses down to the region where cell division occurs
Describe the role of auxin in phototropism
If light shines all around the tip, auxin is distributed evenly throughout and the cells in the shoot grow at the same rate
When light shines on the shoot predominantly from one side, the auxin produced in the tip concentrates on the shaded side, making the cells on that side elongate and grow faster than the cells on the sunny side
This unequal growth on either side of the shoot causes the shoot to bend and grow in the direction of the light
NERVOUS VS ENDOCRINE: Parts of system
NERVOUS: Brain, spinal cord, neurones/ nerves
ENDOCRINE: Glands
NERVOUS VS ENDOCRINE: Type of message
NERVOUS: electrical impulse
ENDOCRINE: Chemical hormone
NERVOUS VS ENDOCRINE: Method of transmission
NERVOUS: Nerves/neurones
ENDOCRINE: Bloodstream
NERVOUS VS ENDOCRINE: Effectors
NERVOUS: Muscles or glands
ENDOCRINE: Target cells in specific tissues
NERVOUS VS ENDOCRINE: Speed of transmission
NERVOUS: Very fast
ENDOCRINE: Slower
NERVOUS VS ENDOCRINE: Length of effect
NERVOUS: Short until electrical impulses stop
ENDOCRINE: Longer, until hormone is broken down.
How are neurones adapted?
- Many extensions called dendrites extend out from the cell body of the neurone and at the far end of the axon
- This means neurones can connect to many other neurones and receive impulses from them, forming a network for easy communication
Summarise the pathway through the nervous system.
stimulus → sensory neurone → relay neurone → motor neurone → effector → response
Describe a reflex arc
- The stimulus is detected by a receptor
- A sensory neurone sends electrical impulses to the CNS (The coordinator)
- An electrical impulse is passed to a relay neurone in the CNS
- A relay neurone synapses with a motor neurone
- A motor neurone carries an impulse to the effector
- When stimulated by the motor neurone, a response will be produced by the effector.
This all occurs within a fraction of a second
How is an impulse passed along a synpase?
- The electrical impulse travels along the first axon
- This triggers the end of the presynaptic neurone to release chemical messengers called neurotransmitters from vesicles
- The neurotransmitters diffuse across the synaptic cleft and bind with receptor molecules on the membrane of the second neurone
- This stimulates the second neurone to generate an electrical impulse
- The neurotransmitters are then destroyed to prevent continued stimulation of the second neurone
- Synapses ensure that impulses only travel in one direction, avoiding the confusion that would be caused within the nervous system if impulses were able to travel in both directions
What happens to the ciliary muscles, suspensory ligaments and lens when an object is close up?
The ciliary muscles contract
suspensory ligaments loosen
lens becomes fatter
Light is refracted more
What happens to the ciliary muscles, suspensory ligaments and lens when an object is far away?
The ciliary muscles relax
suspensory ligaments tighten
Lens becomes thinner
Light is refracted less
What happens to the pupil in dim light?
- Radial muscles CONTRACT
- Circular muscles RELAX
- Pupil DILATES
What happens to the pupil in bright light?
Radial muscles RELAX
Circular muscles CONTRACT
Pupil CONSTRICTS
Describe the role of sweating
This cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour
Describe the role of flattening hairs
The hair erector muscles in the skin relax, causing hairs to lie flat
This stops them from forming an insulating layer by trapping air and allows air to circulate over skin and heat to leave by radiation
Describe the role of shivering
This is a reflex action in response to a decrease in core body temperature
Muscles contract in a rapid and regular manner
The metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature
Describe the role of erection of hairs
The hair erector muscles in the skin contract, causing hairs to stand on end
This forms an insulating layer over the skin’s surface by trapping air between the hairs and stops heat from being lost by radiation
Adrenaline and how it prepares the body for action
- An increase in heart rate and breathing rate - ensures glucose and oxygen can be delivered to muscle cells at faster rate
- Diverting blood flow towards muscles and away from non-essential parts of the body such as the alimentary canal - ensures an increased supply of the reactants of respiration
- Dilation of the blood vessels inside muscles - ensures more blood can circulate through them
- Breaking down of stored glycogen to glucose in the liver and muscle cells ensures a higher blood glucose concentration for increased respiration in muscle cells
