2 Nervous and chemical coordination, page 84 - 103 Flashcards
How are we able to detect changes in our environment?
Through a stimulus and a response.
What is a stimulus?
A change in an animals surroundings.
What is a response?
A reaction to that change.
What is a summary of the sequence of coordination system?
1) Stimulus.
2) Receptor.
3) Coordination.
4) Effector.
5) Response.
What is the information that nerve cells transport called?
Nerve impulses.
What is the role of the receptor?
It is to detect the stimulus by changing its energy into the electrical energy of the nerve impulses.
What are nerve cells called?
neurones.
What two organs make us the Central Nervous System?
- Spinal cord.
- Brain.
What is the CNS linked to?
Sense organs by nerves.
Where do impulses from receptors go through?
The CNS.
What are motor neurones?
They transmit impulses to the muscles and other glands
What are dendrons?
Extension of the cytoplasm of a neurone that carries impulses towards the body.
What are dendrites?
Fine extensions of the dendrons of a neurone.
What is the axon?
Long extension of a neurone that carries nerve impulses in a direction away from the cell body.
How does the axon connect with a muscle?
Neuromuscular junction.
What is the sclera?
The tough outer coat of the eye.
What is the cornea?
It lets light into the eye. It is at the front of the eye and it becomes a transparent window
What is the iris?
The coloured ring of tissue called the iris.
What is the hole in the iris callled?
The pupil.
Why is the pupil black?
Because there is no light escaping from inside the eye.
What is the chloroid?
It is the dark layer underneath the sclera. It stops light from being reflected around the eye.
What is the retina?
- The inner-most layer.
- Light energy is converted into the electrical signals of nerve impulses here.
- Contains rods and cones which are sensitive to light .
What links the eye to the CNS?
The optic nerve.
What is the fovea?
It is a vey concentrated cone part of the eye.
Why can we see so clearly when we look at something?
Cones give a sharper image of rods and because we are directly looking at something that means that the image falls in the fovea.
How do we form an image?
The light we see is refracted on our lens and cornea.
This refraction causes the image to be produced upside down but our brain interprets it as the right way up.
What happens to your iris when in bright light?
- Circular muscles contract.
- Radial muscles relax.
- Pupil constricts to allow less light in.
What happens to your iris when in dim light?
- Radial muscles contract.
- Circular muscles relax.
- Pupil dilation to allow more light in.
Why does the iris reflex happen?
It is a reflex action to allow the right intensity of light to gall on the retina.
What happens if the light is too bright?
It can damage the rods and cones in the eye.
What is the blind spot?
The structure in the eye which has no rods and cones.
Why do we see full images even if we have a blind spot?
The brain puts the images from each eye together, cancelling out the blind spot from each eye.
What happens to the iris when we focus on a distance object?
- Ciliary muscles relax.
- Suspensory ligaments pulled tight.
- Lens becomes flat.
What happens to the iris when we focus on a nearby object?
- Ciliary muscles relax.
- Suspensory ligaments relax.
- Lens becomes more rounded.
What is the nerve pathway of a reflex called?
The reflex arc.
The arc goes into the CNS and then comes out again.
How does a simple reflex arc work?
- The stimulus is detected by temperature or pain receptors in the skin.
- These generate impulses in Sensory neurons.
- The impulses enter the CNS through a part of the spinal nerve called the dorsal root.
- Well in the sensory neurone they are connected by synapses with short relay neurones which in turn connect to motor neurones.
- The motor neurones emerge from the CNS by the ventral root and send impulses back to the muscle and the arm.
What are synapses?
Connect the neurones to the CNS.
How do synapses work in connecting neurones and transmitting a message?
- The synapse is actually a gap between two nerve cells.
- The Gap is not crossed by the electrical impulses passing through the two neurones but by chemicals.
- Axons secrete a chemical called neurotransmitters.
- After the neurotransmitter has passed on the message it is broken down by an enzyme.
Nervous system?
- Information passes through nerve cells and chemicals at synapses.
- Nerve impulses travel fast and have an immediate effect.
- Response is usually short-lived.
- Very localised effect as they usually act on individual cells.
Endocrine system?
- Works by hormones transmitted through the bloodstream.
- Hormones travel more slowly and generally take longer to act.
- Response is usually longer-lasting.
- Hormones can have a widespread effect on different organs.
What gland secreted adrenaline?
The adrenal glands.
What does adrenaline do?
Prepares the body for physical activity.
What gland secretes insulin?
The pancreas.
What does insulin do?
Lowers blood glucose.
What gland secretes testosterone?
Testes.
What does testosterone do?
Controls the development of male secondary sexual characteristics
What gland secretes progesterone and oestrogen?
The ovaries.
What does progesterone do?
Regulates the menstrual cycle.
What does oestrogen do?
Controls the development of female secondary sexual characteristics.
What are the effects of the release of adrenaline?
- Breathing rate increases and breaths become deeper = taking more oxygen into the body.
- Heart beats faster, sending more blood to the muscles, so that they receive more glucose and oxygen for respiration.
- Blood is diverted away from the intestine and into the muscles.
- The pupils dilate = increasing visual sensitivity to movement.
- Body hair stands upright, making the animal look larger.
- Mental awareness is increased so the reactions are faster.
What are the effects of the release of adrenaline on insulin levels?
When the body is short of glucose, the glycogen can be broken down into glucose, which then passes into the bloodstream.
What is diabetes?
When peoples’ pancreas cannot make enough insulin to keep their blood glucose levels constant, so it rises to very high concentrations.
What are some symptoms of diabetes?
- Glucose is found in their urine due to high blood sugar levels.
- Constant thirst.
- Weight loss and weakness.
What does insulin do in terms of glucose?
Store it as glycogen, which can be used as an alternative to glucose.
