Topic 5 - Homeostasis and response Flashcards
(98 cards)
Why do plants produce hormones?
To control and coordinate growth and responses to light (phototropism) and gravity (geotropism)
What is auxin?
It is the hormone that control growth near tips of roots and shoots.
What does unequal distribution in auxins in roots and shoots cause.
Causes unequal growth
What is positive phototropism and where does it take place and is there more auxin on the bright or shaded side and what does this cause?
Phototropism is a positive response in shoots so the shoot bends towards the light. There is more auxin on the shaded side this causes increased cell growth.
What is negative phototropism and where does it take place and is there more auxin on the bright or shaded side and what does it cause?
Negative phototropism takes place in the roots and it bends away from the light. More auxin is on the shaded side but inhibits growth or cell elongation.
Define homeostasis.
Homeostasis is the regulation of internal conditions to maintain optimum internal environment in response to internal or external change
What are the three main thing homeostasis controls?
Body temperature - 37°C
Blood Glucose Concentration
Water levels
What is homeostasis controlled by?
Nervous system and the hormonal system (endocrine system)
What is the cyclical process where the nervous system and the endocrine controls homeostasis.
1) Receptors in organs detect changes in internal or external environments (stimuli)
2) Information is sent via hormones or nervous impulses.
3) Coordinators such as the brian, spinal cord and pancreas process information and sends information via hormones or nervous impulses.
4) The information is sent to the effectors which respond to the stimulus. Effectors are either muscles or glands.
What is the nervous system made of?
The CNS = brain + nervous system
The nerves - bundles of nerve cells.
What is the nervous system used for?
Allows humans to react to their surrounding and coordinate their response.
What do nerves transmit to send information?
Electrical impulses.
What are reflexes?
Reflexes are unconscious and do not involve the brain. They only use three neurones. Reflexes are designed to keep the body safe from harm.
What happens in the reflex arc when you move your hand away from a pin?
Receptors in the skin detect the stimuli (sharp pin).
Then an electrical impulse is sent along a sensory neuron to the spinal cord.
Then an impulse passes through a relay neurone in the spinal cord (coordinator).
Then the relay neurone sends an impulse along a motor neurone to the muscles.
The muscles (effector) contract, pulling your hand away quickly.
What is a synapse?
A gap between two neurones.
Chemical released diffuses across the gap and binds to receptors on next neurone to trigger the electrical impulse.
What is the name of the chemical released at the synapse?
Neurotransmitters
What is the brain made of?
Billions of interconnected neurones.
Where is the cerebral cortex and what is the role of it.
It controls conscious thought, language, memory and intelligence. (Higher brain functions)
Where is the cerebellum and what does it do?
Coordinates muscle contractions and helps with balance and control of the body.
Where is medulla and what does it do.
Controls unconscious behaviours like heart and breathing rate.
Where is the pituitary gland and what does it do?
How is the brain studied?
Studying people with brain damage/injury.
Electrically stimulating the brain or measuring electrical activity.
MRI scans to visualize the brain structure.
What are the ethical issues with studying people with brain damage?
Need Consent for this.
Why is the brain so difficult to understand and treat.
Inside a skull so hard to access to see how it works and treat it. It is complex (not fully understood) and is delicate (easily damaged in surgery). Nervous tissue is difficult to repair/replace. Not all drugs can reach the brain due to membranes.
