Tags & Description
How does sweat keep us cool?
As sweat evaporates, it removes heat energy from the skin
State which direction the plant will grow and explain why?
The shoot will grow towards the left. This is because the light is on the left, and so auxins will accumulate on the right side(which will be in the shade). Auxins stimulate growth in shoots so the right side will grow faster, causing the shoot to lean over to the left.
What happens to make a root grow in the direction of the force of gravity?
The top side grows more than the bottom side?
What effects do auxins have on plants?
Shoot cell growth and root cell inhibition.
What is the cornea?
A transparent layer at the front of the eye that refracts light
Optic nerve
Carries electrical impulses to the brain
What is the retina?
Has photoreceptors that receives messages and sends them as electrical signals through the optic nerve to the brain
Pupil
Gap through which light passes through to the lens
What is the lens?
The lens refracts light and focuses it on the retina
What types of cells does the retina have and what do they do?
The cone cell detects colour. The rod cells detect light.
What is the fovea?
The point where the light on the retina
What is the purpose of the iris reflex?
To ensure the optimum amount of light enters the eye
What do muscles make up the iris?
Circular and radial muscles
What happens to the circular and radial muscles when the pupils constrict?
The radial muscle contracts and the circular muscle relaxes.
What is homeostasis?
The maintenance of stable internal body environment despite changing conditions?
Why does the body need to contain optimal conditions?
For optimal enzyme action and cell function
What is the role of a receptor?
Detects change in the internal or external environment
What is the role of a coordination centre?
Interprets changes and organises a response
Where are the coordination centres located in the body?
Spinal cord and brain
Name two types of effectors and what they can do
Muscles contract when stimulated. Glands release hormones.
Which system is faster at reacting?
Nervous system
Which system acts more generally across the body?
The endocrine systems because hormones are releases into the bloodstream which means it’s spread throughout the body.
Homeostasis relies on a system of……….
Negative feedback
What is the role of effectors?
To carry out the response
Where is auxin produced?
In the tips of roots and shoots
Auxins always accumulate on the……….
Lower and shaded side
Shoots are…….
Negatively geotropic/gravitropic and positively phototropic
What shape should the lens be when looking at a nearby object?
Fat and short
Only muscles……..
contract
When looking at a nearby object?
The suspensory ligaments slacken and the ciliary muscles contract.
What type of lens should glasses for long-sighted people contain?
Convex lens
Does the effect of the endocrine or nervous system last longer?
The endocrine system because hormones stay in the bloodstream for a long time and electrical impulses last for a split-second.
Explain the reflex arc.
The stimulus(heat) us detected by the receptors(thermoreceptors). Impulses are sent along a sensory neuron. In the CNS, the impulse passes to a relay neuron. Impulses are sent along a motor neuron. The impulse reaches an effector which results in an appropriate response to a stimulus.
progesterone
Produced in ovaries, maintains pregnancy and maintains the uterus lining so that the fertilised egg can implant
oestrogen
Produced in ovaries, main sex hormone in females and produces secondary sexual characteristics in females such as developing breasts.
insulin
produced in pancreas and maintains blood sugar/glucose levels
vasodilation
widening of blood vessels as a result of relaxation of smooth muscle cells within the vessel cells to allow more blood to flow closer to the surface of the skin resulting in increased energy transfer from the body and so more heat is lost from the body and the body cools down
adrenaline
Produced in adrenal gland, prepares the body for flight/fight response and increases heart/breathing rate
vasoconstriction
Narrowed blood vessels and so not as much blood flows to the skin surface and this means less bodily heat is lost
thermoregulatory centre
monitors and controls body temperature to ensure it remains the same temperature found in the brain. has receptors that monitor the temperature of the blood. it has receptors that monitor the temperature of the blood. receptors in the skin that send impulses to the thermoregulatory centre
Explain plant tropism in roots
Most roots show positive gravitropism as they grow towards gravity. If a root is horizontal, auxin moves to the lower side. The cells of the root grow more on the side with less auxin, so it stimulates the cells to grow on the upper side. This makes the root bend and grow downwards. This is beneficial as there are more likely to be increased levels of water and nutrients lower down and it provides stability for the plants.
What are neurotransmitters?
The chemical released at one end of a nerve fibre
What is the nervous system?
A bodily system made up of nerve cells that carry impulses around the body
How do electrical impulses travel across a neuron?
An electrical nerve impulse travels along the first axon. This triggers nerve-endings to release neurotransmitters. This is because the electrical impulse cannot directly travel across the synapse and so needs to be converted to a chemical and then back to an electrical impulse. The neurotransmitter diffuses across the synapse and binds to a receptor molecule on the next neuron. This stimulates the next neuron to transmit the electrical impulse.
Nervous System:
Type of signal: Electrical
Transmitter: Nerve cells
Speed of response: very fast
Duration of response: short
Electrical System
Type of signal: Chemical
Transmitter: Hormones in bloodstream
Speed of response: Slower
Duration of response: Long
Explain shivering
Shivering is your body muscles contracting which you respire more, which means more energy is released in your body and this energy is produced as heat energy
3 responses in the body for hot body temp
hairs lay flat, vasodilation and sweating
3 responses in the body for cold body temp
hairs lay up, vasoconstriction and shivering