Co-ordination And Control Flashcards
What is a stimulus?
Anything that we respond to/triggers an impulse
What does an effector affect?
A receptor
What happens when a receptor is stimulated?
It causes an effector to produce a response
What are receptors and effectors connected by?
A coordinator, usually the brain but may also be the spinal cord
(CNS)
What are the brain and spinal cord known as?
The central nervous system
What links the receptors and effectors to the coordinators?
Nerve cells or neurones
What do neurones carry information as?
Small electrical charges called nerve impulses
How are neurones adapted? (4)
– They have a nucleus that controls the activities of the neurone
– They have long axons so that nerve impulses can be carried across long distances throughout the body
– They have a fatty layer called the myelin sheath that acts as an insulator that helps to speed up the nerve impulses
– The branched ends of the axon allow the neurone to make junctions with other nerve cells
What is a synapse?
The junction between two neurones
How are nerve impulses transferred from one neurone to another?
- When an electrical impulse reaches the end of the axon, it causes the axon to release a special chemical called the transmitter substance (neurotransmitter) which diffuses across the gap.
- If the concentration of transmitter substance is high enough on the other side of the synapse, it triggers an electrical impulse on the axon leaving the junction and the nerve impulse continues on its way
What is a voluntary action?
An action we do deliberately that involves conscious thought
What is a reflex action?
An action that does not involve conscious thought that happens automatically, like breathing or blinking
What are the two main characteristics of a reflex action?
- They occur very rapidly
and - do not involve conscious control
What makes reflex actions so rapid?
In a reflex pathway, the length of the pathway is kept as short as possible with the minimum number of neurones needed and as few synapses as possible
What is a reflex arc?
The nerve pathway involved in a reflex action
What is the sensory neurone?
The neurone that carries information from receptors
What is the motor neurone?
The neurone that carries information from the spinal cord back to the effector, causing a response
What is the association / connector / relay neurone?
The neurone that connects the sensory and motor neurone
What does the iris do?
Controls how much light enters the eye
What is the pupil?
The space in the iris through which light passes
What is the cornea?
The transparent front part of the eye that allows light to enter the eye and causes some refraction
What is the aqueous humour?
The transparent, incompressible watery liquid that helps focussing and to maintain the eye’s shape
What is the conjunctiva?
The thin, transparent, protective outer covering of the eye
What is the retina?
The inner coat of the eye where light-sensitive cells are found
What is the lens?
The coloured disc which controls the pupils diameter and the amount of light entering the eye
What is the vitreous humour?
Jelly-like substance that helps maintain the shape of the eye and keeps the retina against the wall of the eye
What is the optic nerve?
Nerve that contains neurones carrying information to the brain
Where is the blind spot?
Where the optic nerve creates a gap in the retina
What is the suspensory ligament?
Ring of strong fibres supporting the lens that stretch and slack to allow different amounts of light to enter the eye
What are the ciliary muscles?
Ring of muscles that pull on the suspensory ligament to change the shape of the lens and allow different amounts of light into the eye
Why is controlling the amount of light entering the eye important?
If too little or too much light enters the eye and reaches the retina, it can damage the sensitive light receptor cells in the retina
What happens to the pupil in dim light?
The size of the pupil is increased to allow more light to enter the eye
What happens to the pupil in bright light?
The size of the pupil is decreased to restrict the amount of light entering the eye
What is negative feedback?
Negative feedback is a control system that responds to changes in conditions from the ideal or set point and returns conditions to this set point
What does insulin do to the blood glucose concentration?
It limits the concentration
Where is insulin produced and released?
The pancreas
What causes insulin to be produced?
In response to increasing or high blood glucose concentrations
What does insulin achieve?
The prevention on the concentration of glucose in the blood becoming too high
Why does the concentration of glucose in the blood need to be limited?
Too much glucose can damage body cells due to water loss
What is the main target organ for insulin and what effects does it have? (3)
The main target organ for insulin is the liver where it causes:
– Increased absorption of glucose from the blood, reducing blood glucose concentration;
– The conversion of excess glucose into glycogen which is stored in the liver
– Increased respiration
What is a hormone?
A chemical messenger produced by special glands which release them into the blood
What is the organ that a hormone affects called?
The target organ
What is homeostasis?
Keeping the body in a constant state in response to changes outside and inside the body
What is osmoregulation?
A homeostatic process that controls the amount of water in the blood and other body fluids
What is diabetes?
A condition in which the body does not produce enough insulin to keep the blood glucose at the normal concentration
What 3 ways does the body gain water?
- Drinking liquids
- in food
- water as a product from respiration
How does the body lose water?
- evaporation of sweat
- breathing out water vapour
- in urine
Give the steps taken by the body when blood is too dilute
- blood concentration normal
- large drink of liquid
- blood too dilute
- kidney reabsorbs less water back into blood and more urine is produced (LESS ADH)
Give the steps taken by the body when blood is too concentrated
- blood concentration normal
- lots of water lost (eg sweat during exercise)
- blood too concentrated
- kidney reabsorbs more water back into blood and less urine is produced (MORE ADH)
What is ADH? Where is it produced and what is it’s target organ?
ADH (anti diuretic hormone) is a hormone which controls how much water the kidney reabsorbs
It is produced in the brain and it targets the kidneys
What blood vessel supplies the kidney?
What blood vessel exits the kidney?
- The renal artery (supplies blood for filtering)
- the renal vein (returns filtered blood to the vena cava)
Name each part of the kidney (at this level obvs)
Also
Name the other parts of the excretory system
- renal pelvis
- medulla (middle part of the kidney)
- cortex (outer part of kidney)
Other parts of excretory system
- ureter (tube to bladder)
- bladder
- sphincter muscle (holds urine in bladder)
- urethra (take urine out of the body)
What is phototropism?
The growth response by plants in which they grow in the direction of light
Why does phototropism occur?
and
how does it work?
Phototropism occurs when a plant receives light from one direction (unilateral)
It works as auxin (a hormone) is released from the tip of the plant and travels disproportionately to the shaded part of the plant (it travels in such a way due to the direction from which the tip receives light).
More auxin is on the shaded part of the plant, causing the plant to grow more on this side and therefore, bend toward light
Explain in detail accommodation in the eye when looking at a close object (3)
- Ciliary muscles contract;
- suspensory ligaments slacken;
- lens becomes fatter/thicker/bulges
Explain in detail accommodation in the eye when looking at a distant object (3)
- Ciliary muscles relax;
- suspensory ligaments tighten;
- lens becomes flatter/thinner/less rounded