coordination and response Flashcards
what are the parts of the nervous system
- central nervous system
- peripheral nervous system
what is the central nervous system
Central nervous system (CNS) consisting of the brain and spinal cord, which are the areas of coordination
what is the peripheral nervous system
Peripheral nervous system (PNS) made up of nerves and neurones, which coordinate and regulate bodily functions.
what are involuntary actions
not under conscious control e.g. reflex action
what are voluntary actions
are done if we decide to carry them out
what are nerve impulses
an electrical signal that passes along nerve cells called neurones
types of neurones
- motor neurone
- sensory neurone
- relay (connector) neurone
what is a reflex action
A reflex action is an involuntary, quick action to respond to a stimulus, in order to protect the body from danger
means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)
E.g. quickly removing your hand from hot metal surface
They involve three neurones: a sensory neurone, relay neurone and motor neurone.
what is a synapse
The gap between neurones is called a synapse. a junction between two neurones, consisting of a gap across which impulses pass by diffusion of a neurotransmitter
how the reflex arc works
A stimulus affects a receptor (cell or organ that converts a stimulus into an electrical impulse)
A sensory neurone carries impulse from the receptor to the CNS
Connector/relay neurone carries impulse slowly (because it has no myelin sheath) across the spinal chord
Motor neurone carries impulse from the CNS to the effector
Effector (either a muscle or a gland) carries out the response
what is a synaptic cleft
small gap between each pair of neurones
describe diffusion of a neurotransmitter (synapses)
Inside the neurones axom, there are 100s of tiny vacuoles (vessicles each contain a chemical called neurotransmitter)
When an impulse arrives, the vessicles move to the cell membrane and empty their content into the synaptic cleft
The neurotransmitter quickly diffuses across the tiny gap and attaches to receptor molecules in the cell membrane of the relay neurone
This can happen because the shape of the neurotransmitter molecules is complimentary to the shape of the receptor molecule
Many drugs e.g. heroin act upon synapses
what are antagonistic muscles
A muscle that opposes the action of another; e.g. biceps and triceps are antagonistic muscles or circular and radial muscles in the eye
what is an agonist muscle
a muscle that contracts while another relaxes; e.g. when bending the elbow, the biceps are the agonist
what is an antagonist mucsle
a muscle that relaxes while another contracts; e.g. when bending the elbow, the triceps are the antagonist
what are sense organs
groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals.
what is the eye
The sense organ responsible for sight
parts of the eye
Cornea: refracts light
Iris: controls how much light enters pupil
Lens: focuses light onto retina
Retina: contains light receptors, some sensitive to light of different colours
Optic nerve: carries impulses to the brain
what is (sensory) accomodation
- adjusting for near and distant objects
- light rays from distance objects are parallel so do not need much refraction to focus properly
- light rays from closer objects diverged and need much refraction to focus properly
what happens to the eye when viewing a near object
- ciliary muscles contract
- ligaments relax
- lens becomes short nd fat
what happens to the eye when viewing a distant object
- ciliary muscles relax
- ligaments are tight
- lens becomes long and thin
what is pupil reflex
-adjusting for high and low light intensity
pupil reflex in low light intensity
Radial muscles (straight lines) contract and become shorter to pull the pupil (black dot) making it wider, to let more light enter, to form a clear image on retina
pupil reflex in high light intensity
Circular muscles (circular lines) contract and become shorter to reduce the size of the pupil to protect retina from bleaching.
what are rods
- Provide low detail, black & white images, good for seeing in low intensity light (at night).
- Packed most tightly around edge of retina so you can see things most clearly when not looking directly at them.
what are cones
- Provide detailed, coloured images; they work in high light intensity.
- Most tightly packed at centre of retina, so objects are seen most clearly when being directly looked at.
what is the fovea
Part of the retina where the receptor cells are pushed most closley together
Where light is focused when you look straight at an object
has the highest concentration of light sensitive cells and gives the most detailed image
what are hormones
A chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver.
what is adrenaline
A hormone secreted by the adrenal gland.
It increases pulse rate, makes the glycogen in muscles get converted to glucose, and released into blood, makes you breath deeper and more rapidly, airways become wider, and makes skin become pale as blood is diverted away.
Increases conc. of glucose in the blood for respiration.
Adrenaline is secreted for example: while bungee jumping or riding a rollercoaster
function of adrenal gland
- secretes adrenaline
- Prepares body for vigorous action
function of pancreas
- secretes insulin
- Reduces conc. of glucose in blood
function of testis
- secretes testosterone
- Causes development of male sexual characteristics
function of ovary
- secretes oestrogen
- Causes development of female sexual characteristics
comparison of nervous and hormonal system speed of action
- nervous: rapid
- endocrine: can be slow
comparison of nervous and hormonal system nature of message
- nervous: Electrical impulses, travelling along nerves
- endocrine: Chemical messenger (hormones) travelling in bloodstream
comparison of nervous and hormonal system duration of response
- nervous: Usually within seconds
- endocrine: May take years (puberty)
comparison of nervous and hormonal system area of response
- nervous: Localized response (only one area usually)
- endocrine: Widespread response (in many organs)
comparison of nervous and hormonal system example of process controlled
- nervous: Reflexes such as blinking
- endocrine: Reflexes such as blinking
use of hormones in food production advantages and disadvantages
Hormones are used in food production, for example oestrogen is used to boost growth rate of chickens.
Advantage: chickens grow quickly meaning more profit.
Disadvantages: this may cause human males to develop feminine characteristics, and it is unnatural.
what is homeostasis
The maintenance of a constant internal environment.
Homeostasis is the control of internal conditions within set limits
what is negative feedback
Feedback controls the production of hormones – the hormones regulate their own production.
A negative feedback control is when the change in hormone level acts as a signal to cancel out that change, so when blood hormone level is low, hormone production is stimulated, when it is high, it is inhibited.
what is glucoregulation
Blood glucose levels are monitored and controlled by the pancreas
The pancreas produces and releases different hormones depending on the blood glucose level
Insulin is released when blood glucose levels are high – the liver stores excess glucose as glycogen
Glucagon is released when blood glucose levels are low – the liver converts stored glycogen into glucose and releases it into the blood
what is type 1 diabetes
When the control of blood glucose does not work, a person is said to have diabetes
Type 1 diabetes is caused by the death of the cells that secrete insulin
symptoms of type 1 diabetes
hyperglycaemia (feel unwell, dry mouth, blurred vision and feel thirsty) or hypoglycaemia (tired, show confusion and irrational behaviour)
treatment of type 1 diabetes
eating little and often and avoiding large amount of carbohydrates, injecting insulin to reduce blood glucose concentration
thermoregulation of insulation
provided by fatty tissue retains heat. Hairs become erect to trap warm air by contracting erector muscles and vice versa.
thermoregulation of vasodilation
when it is hot, arterioles, which supply blood to the skin-surface capillaries, dilate (become wider) to allow more blood near to skin surface to increase heat loss (face redder)
thermoregulation of sweating
the water evaporates giving a cooling effect
thermoregulation of skin receptors
sense heat and sensory neurons send impulses to the hypothalamus
thermoregulation of shivering
muscular activity generates heat
thermoregulation of thermoregulatory centre
in the hypothalamus, it controls the use of corrective mechanisms (e.g. sweating and shivering).
homeostasis of cells
change composition of blood as they remove nutrients and O2 and add wastes and CO2
homeostasis of heart
keeps blood pressure constant to deliver oxygen and nutrients around body
homeostasis of skin
to maintain heat exchange with external environment
homeostasis of kidneys
regulate water and salt levels (osmoregulation) and the removal of wastes like urea (excretion)
homeostasis of lungs
regulate gas exchange
homeostasis of intestines
Intestines: supply soluble nutrients and water to blood
homeostasis of liver
regulates blood solutes and removes toxins
homeostatic organs
- cells
- heart
- skin
- kidneys
- lungs
- liver
what is auxin
Plant hormones or growth substances
Controls tropisms
It is produced by cells at the tip of roots and shoots of plants
what is gravitropism
a response in which a plant grows towards (positive) or away (negative) from gravity.
auxins role in gravitropism
Tend to settle at the bottom end of the root.
However, this does not make the cells of the tip of the root grow longer; auxins prevent cells at bottom tip of root from growing, making cells at top of root grow faster.
When cells of top of the root grow faster, they push root deeper into soil and root gets longer.
The root grows in direction of the gravitational pull.
what is phototropism
a response in which a plant grows towards (positive) or away (negative) from the direction from which light is coming.
auxins role in phototropism
If sun shines on right side of a plant’s shoot, auxins will accumulate on dark opposite left side.
Auxins accumulating makes cells on left side grow faster than cells on right side.
When left side of shoot starts growing faster than right side, shoot will start to bend to right side towards sunlight.
use of hormones as weed killers
Hormones can be used as weed killers: spraying with high concentrations of hormone (2,4-D) upsets normal growth patterns. It affects different species differently so might only kill one species not the other (this is good).
2,4-D is a weedkiller / AW ;
sprayed on crops / applied to leaves ;
specific to broadleaved weeds ;
does not affect, cereals / narrow-leaved crop plants ;
causes uncontrolled growth
structure of neurones
Neurones have a long fibre (axon)
This means that less time is wasted transferring the impulse from one cell to another
The axon is insulated by a fatty sheath with small uninsulated sections along it (called nodes)
This means that the electrical impulse does not travel down the whole axon, but jumps from one node to the next
Their cell body contains many extensions called dendrites
This means they can connect to many other neurones and receive impulses from them, forming a network for easy communication
advantages of coordinating endocrine and nervous system
4(d) nervous system, responds quickly / immediately ; ora
idea that (nerve) impulses travel to, (specific) muscles / (adrenal) glands
/ effector(s) ;
effects of endocrine system are long lasting ; ora
hormones / adrenaline, travels throughout the body / allows multiple
(target) organs to respond (to same signal) ;
idea that less energy required than to have nerves going to every, cell / tissue ;
stimulate both voluntary and involuntary responses (simultaneously) ;
more effective / enhanced, response (than using one system alone) ;
