Flashcards in Nerves and Hormones Deck (38):
What happens when a receptor is stimulated?
A signal is sent along neurones (nerve cells) to the brain. the brain then co ordinates the response
What are neurones?
Nerve cells that carry information as tiny signals.
What are the different types of neurone?
Sensory- Carry signals from receptors to spinal cord or brain
Relay- Carry messages from one part of the CNS to the other
Motor- Carry signals from the CNS to the effector
What is a synapse?
A gap between two neurones. Electrical signals diffuse as a chemical across a synapse and turns into an electrical signal again
What happens in a reaction:
receptor detects a stimulus - a change in the environment
sensory neurone sends impulses to relay neurone
motor neurone sends impulses to effector
effector produces a response.
What are receptors?
Groups of specialised cells that can detect a change in the environment called a stimuli.
Receptors are located in the sense organs e.g. eyes, ears
What are hormones?
Chemical substances secreted by glands which travel to target organs through the bloodstream.
How is water loss controlled?
Water loss is controlled by losing water from:
The lungs- when we exhale
The skin- through sweating
Urine- produced by the kidneys
Salt content is controlled through the skin and urine the same way
How are blood sugar levels controlled?
Blood sugar level is controlled by the release and storage of glucose controlled by insulin.
Secreted by the pituitary gland.
-Causes an egg to mature in the ovary
-Stimulates the ovaries to release the hormone oestrogen
Secreted by the ovaries.
-Stops FSH from being produced so that only one egg matures
-Stimulates the pituitary gland to release LH (lutenising hormone) which triggers ovulation (release of mature egg)
Greatly reduces the chances of mature eggs being produced.
Contains oestrogen and progesterone which stimulates FSH production, stopping eggs maturing
Benefits of contraceptives:
Allows couples to choose when they want to start a family and when to stop having children.
Increases a womans chance of becoming pregnant, doesnt always work.
Boosts production of mature eggs, increases chance of problems during childbirth eg premature babies
In Vitro Fertilisation:
IVF is used if quality/quantity of a mans sperm is poor. An egg is fertilised outside of the womans body and is implanted back into the uterus. FSH is used to widen the selection of eggs used for IVF.
Ethical implications of IVF:
Some think it is unethical to choose what your baby will be like as it is not our place to prevent life of unwanted embryos.
What is a tropism?
A response to a stimulus
What is auxin?
A plant hormone produced in the stem tips and roots, which controls the direction of growth.
What are plant hormones used in?
Used in weed killers, rooting powder and to control fruit ripening.
Needs light and water.
Produces glucose and oxygen by taking in carbon dioxide and water
The plant grows towards the stimulus
The plant grows away from the stimulus.
Tropism where light is the stimulus.
Where gravity is the stimulus.
light stimulus: positive phototropism
gravity stimulus: negative gravitropism
Light stimulus: negative phototropism.
Gravity stimulus: positive gravitropism.
What does auxin do?
Changes the rate of elongation in plants, controlling how long they become.
Prohibits elongation in roots
Auxin in shoots and roots:
Cells in shoots grow more with high auxin
Cells in roots grow less with high auxin
Which side of a plant contains more auxin?
The shaded side.
What are drugs?
Drugs are substances that change chemical reactions in the body.
Main stages of drug testing:
1. The drugs are tested using computer models and human cells grown in the laboratory. Many substances fail this test.
2.Drugs that past the first test are then tested on animals. It is illegal to test cosmetics and tobacco products on animals.
3.Drugs that pass the second test move onto clinical trials. Healthy volunteers are used to test the substance. If it works, further trials are done to decide the correct dosage.
Double blind trials:
Double blind trials aim to reduce the placebo effect so patients don't get a false sense of recovery. Until the trial is over, both the doctor and the patient don't know if the drug is real.
What is thalidomide?
Developed as a sleeping pill, Then used for morning sickness in pregnant women. Found to damage the development of unborn babies, the drug led to severe limb deformities.
What is thalidomide used for today?
Used to treat leprosy and bone cancer.
What is alcohol?
Alcohol is a depressant, which can slow down signals in the nerves and brain.
Side effects of alcohol:
Long term: Damage to the liver and brain
Short term: Slurred speech
(often causes weight gain)
What is nicotine?
A highly addictive drug contained in cigarettes. Reaches the brain in 20 seconds, cause the user to become addicted.