B1.2 - Nerves and Hormones Flashcards
(26 cards)
What is a neurone?
A cell that transmits electrical nerve impulses, carrying information from one part of the body to another.
What three neurones are involved in a reflect action?
Sensory, relay and motor neurones
What is the function of a sensory neuron?
Carry impulses from the receptor to the spinal cord.
What is the function of a relay neuron?
Carry impulses through the spinal cord and up to the brain and from the brain back along the spinal cord.
What is the function of a motor neuron?
Takes impulses from the spinal cord to an effector.
What is the function of a receptor?
Cells that detect stimuli or changes in the environment. E.g. Eyes, ears, tongue, nose, skin.
What is the function of an effector?
Can be a muscle that is made to contract or a gland that secretes a chemical for example a hormone.
What is the function of a synapse?
The junction of two nerve cells
Describe what happens in a reflex arc
When pain is detected by a receptor, it sends an impulse along a sensory neurone to a relay neurone in the spinal cord. The relay neurone sends an impulse in an arc via a motor neurone to an effector, a muscle, which contracts. This is called a reflex action. It is automatic and very quick.
Why do we need to maintain a constant body temperature?
Body temperature is kept around 37˚C because this is the best temperature for enzymes which speed up chemical reactions inside the body.
What is a hormone?
A chemical messenger
Where are hormones produced?
Glands
How do hormones travel around the body?
In the bloodstream
Which glands control the menstrual cycle?
Pituitary gland
What is the role of follicle stimulating hormone (FSH)?
Stimulates the ovary to produce a follicle. The follicle produces oestrogen.
What is the role of lutenising hormone (LH)?
Causes the follicle to change into a corpus luteum and produce progesterone.
What is the role of oestrogen?
Prepares the uterus for a fertilised egg.
What impact do the hormones in oral contraceptives have on the hormones in the body?
The pill contains hormones that have the same effect on the pituitary gland as oestrogen. These hormones stop the pituitary gland making the hormone FSH. This means that no eggs will mature in the ovaries.
How have birth control pills changed over time and why?
The first pills had large amounts of oestrogen. These resulted in women suffering significant side effects such as the formation of blood clots. The pill now contains much lower dosage of oestrogen.
Which hormones will be included in “fertility drugs”?
FSH
What happens during in vitro fertilisation (IVF)?
The female is given injections of FSH to stimulate the maturation of several eggs. Eggs are then collected just before they are released from the ovary. The eggs are fertilised with sperm outside the body and the fertilised eggs are allowed to divide to form embryos. Some are inserted into the womb.
List three things that plants are sensitive to:
1) Light
2) Gravity
3) Water
What is the name of the hormone in plants?
Auxin
What is phototropism?
The response of plants to light, Stems grow towards the light. This response to directional light is called phototropism. Plant stems are positively phototropic, that is they grow towards the light stimulus.
