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Unit 7: Coordination and Response
Terms in this set (19)
The Nervous system?
consist of two parts the central nervous system which is the brain and spinal cord which are the areas of coordination and the peripheral nervous system made up nerve and neurons which coordinate and regulate bodily functions.
a reflect action is an involuntary, quick action to respond to a stimulus, in order to protect the body from danger e.g. removing your hand from a hot metal surface. They involve three neurons: a sensory neuron, relay neuron and motor neurons. The gap between is called synapse. The reflex arc works like this:
1) A stimulus affects a receptor (cell or organ that converts a stimulus into an electrical impulse.
2) A sensory neuron carries impulse from receptor to CNS.
3) Connector/relay neuron carries impulse slowly (because it has no myelin sheath (insulator) across the spinal cord.
4) Motor neuron carries impulses from the CNS to the effector.
5) Effector (either a muscle or a gland) carries out the response.
Adjusting for near and distant objects. Distant objects have parallel light rays, needing only a little refraction, ciliary muscles relax, eyeball becomes spherical, ligaments are tight and the lens becomes long and thin. Close objects have diverging light rays needing more refraction, ciliary muscles contract, ligaments relax and the lens becomes short and fat.
in dim light the circular muscles relax and the radial muscles contract. This dilates (widens) the pupil and so more light is able to reach the retina. In bright light the circular muscles contract and the radial muscles relax. This constricts (narrow) the pupil and so less light reaches the retina to avoid damage.
a chemical substance, produced by a gland, carried by the blood, which alter the activity of one or more specific target organs and is then destroyed by the liver.
a hormone secreted by the adrenal gland. It helps the body prepare for actions
Three examples of adrenaline?
liver cells to convert glycogen to glucose, which diffuses into the blood. This makes more glucose to reach the muscles as a source of energy for the rapid contractions needed for sudden action, the heart rate to increases so that more glucose and oxygen are deliver to muscles for energy release. Dilation (widening) of the airways so more air reaches the alveoli in the lungs for more gas exchange.
Comparing Endocrine and nervous system?
Speed of action: NS: very rapid, ES: can be slow.
forms of information: NS electrical impulses, ES: hormones (chemical).
Example of response: NS: muscle contractions or secretion by glands, ES: many response e.g. Conversion of glucose to glycogen, rate of respiration.
is a growth response to the stimulus of gravity. Roots are positively geotropic and shoots are negatively geotropic.
is a growth response to the stimulus of light. Shoots are positively phototropic and grow towards the light
is a hormones that controls plant growth. Auxin in shoots stimulates growth by causing the cells to elongate, but in roots auxin inhibits growth by slowing down cell elongation.
is the maintenance of a constant internal environment
provided by the fatty tissue retains heat/ prevents heat loss. Hairs become erect to trap warm air by contracting erector muscles.
When it is hot, arterioles which supply blood to the skin surface capillaries, dilate (becomes wider) to allow more blood near to skin surface to increase heat loss (face goes red after running a mile). Sweat gland in the skin produce lots of sweat. The sweat on the skin's surface evaporates and this cools the body.
when it's cold, arterioles near to the surface of the skin becomes narrower to reduce the blood flow through capillaries bear the surface of the skin. Sweat glands stop producing sweat. Shivering by the muscles which start to contract spontaneously and release heat from respiration. Blood flow through the muscles and is warmed by this heat
sense heat and sensory neurons send impulses to the hypothalamus (in brain monitors the temperature of the blooding running through it).
Control by negative feedback?
the production of hormones is controlled by feedback, 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.
When glucose levels are high?
when you eat a high carbohydrate meal your blood glucose concentration can increase. However it doesn't stay high because cells in the pancreas detect the high glucose concentration in the blood. These cells secret the hormones insulin into the blood. Insulin stimulates liver cells to convert glucose into storage compound glycogen. This stimulates the liver cells to absorb lots of glucose from the blood so the concentration decreases and returns to normal.
When glucose levels are low?
When you run or carry out some other type of exercise, your muscle take up lots of glucose from the blood to provide the energy you need. Your blood glucose concentration decreases but it does not keep decreasing. Other cells in the pancreas detect this decrease and secrete the hormone glucagon into the blood. Glucagon stimulates liver cells to break down glycogen to glucose, which diffuses into the blood so the blood glucose concentration increase to normal
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