Nerves And Hormones Flashcards
What does the nervous system do?
It allows us to respond to changes in our environment by coordinating actions.
What is a stimulus?
A change in the environment that you might need to react to.
What detects stimuli?
Sense organs
What are the five sense organs?
- Eyes
- Ears
- Nose
- Tongue
- Skin
What is the Central Nervous System?
Where all information from receptors in the sense organs is sent and processed.
What two things make up the CNS?
The brain and the spinal chord.
Give two examples of effectors and how they can react to stimuli.
- Muscles can contract
* Glands secrete hormones
What is a sensory neurone?
A neurone that carries electrical signals from the receptors to the CNS.
What is a relay neurone?
A neurone that carries electrical signals between the sensory neurones and the motor neurones. They are found in the CNS.
What is a motor neurone?
A neurone that carries electrical signals from the CNS to the effectors.
What is the order of events when the body comes into contact with a stimulus?
Stimulus > Receptor > Sensory Neurones >CNS > Motor Neurones > Effector > Respone
What is a synapse?
The connection between two neurones.
How do electrical signals cross synapses?
The nerve signal is transferred as chemicals called neurotransmitters. They then trigger an electrical signal at the next neurone.
What is a reflex?
A fast, automatic response to a stimulus that bypasses the brim completely to save time.
What is the purpose of a reflex?
To save the body from coming to harm.
Describe the reflex arc.
Stimulus > Receptor > Sensory Neurone > Relay Neurone > Motor Neurone > Effector > Reflex action
What is homeostasis?
The maintenance of a constant internal environment.
What controls all our metabolic reactions?
Enzymes
At what temperature do enzymes work best at?
37 degrees
Why is it important for the body to be kept at 37 degrees?
Else wise the enzymes in the body would denature and so not work properly.
What part of the body controls the body’s temperature?
The thermoregulatory centre in the brain.
What organ removes excess ions from the body?
The kidneys
How can the body lose water?
- Sweat
- Exhalation
- Urination
How is blood glucose controlled?
By being used to create energy or being stored as glycogen in the liver.
What are hormones?
Chemical messengers which travel in the blood to activate target cells. They are generally slow acting and have long-lasting effects.
What produces hormones?
Glands
What works quicker: nerves or hormones?
Nerves
What acts for a longer time: nerves or hormones?
Hormones
Which acts on a more specific area: nerves or hormones?
Nerves
What is the menstrual cycle?
The sequence of events in which a female releases an ovum and prepares the womb in case of fertilisation.
What is Stage One of the menstrual cycle?
Bleeding begins as the uterus lining breaks down. Lasts roughly 4 days.
What is Stage Two of the menstrual cycle?
The uterus lining builds up again. This usually takes ten days.
What is Stage Three of the menstrual cycle?
The ovum is released on day 14.
What is Stage Four of the menstrual cycle?
The wall is maintained for 14 days. If a fertilised ovum is not received, the lining breaks down on day 28.
What does FSH stand for?
Follicle Stimulating Hormone
Where is FSH produced?
The pituitary gland
What does FSH do?
Causes the ovum to mature and stimulates the production of oestrogen.
Where is oestrogen produced?
The ovaries
What does oestrogen do?
Causes production of LH and prevents production of FSH.
What does LH stand for?
Luteinising Hormone
Where is LH produced?
The pituitary gland
What does LH do?
Stimulates the release of the ovum.
What is a contraceptive?
A method of preventing pregnancy.
What two hormones can be used as contraceptives?
Oestrogen and Progesterone.
How does oestrogen act as a contraceptive?
It inhibits FSH production.
How does progesterone act as a contraceptive?
It stimulates the production of thick cervical mucus which prevents sperm from reaching the ovum.
What does “the pill” contain?
Progesterone and oestrogen.
Why did the oestrogen content of the pill have to be reduced?
Because links were made between the pill and blood clots.
What are the benefits of taking the pill?
- 99% success rate
* Reduced risk of some cancers
What are the problems with the pill?
- Not 100% effective
- Some side effects (headaches, nausea etc)
- Doesn’t prevent STIs
How can one increase fertility?
By injecting FSH and LH to stimulate egg maturation and release.
What are the issues with injecting FSH and LH?
- Doesn’t always work
* Can result in unexpected multiple pregnancies
What does IVF stand for?
In Vitro Fertilisation
What is IVF?
A process that can be used to help couples who are having difficulty having children.
Describe the process of IVF
1) FSH and LH are used to stimulate the release of multiple ova
2) Ova are collected from the ovaries
3) The ova are fertilised in a lab using a sample of the father’s sperm
4) The fertilised eggs are grown into embryos. One or two are replaced into the woman’s uterus.
What are the problems surrounding IVF?
- Some woman have strong negative reactions to the hormones
- Links to cancer
- Multiple births and related issues
What is auxin?
A plant hormone found in the tips of roots and shoot. It encourages growth in shoots and inhibits growth in roots.
What is phototropism?
Plant growth in respond to light.
What is gravitropism?
Plant growth in response to gravity.
What happens when a shoot tip is exposed to light?
More auxin accumulates at the shaded side of the shoot. This makes the cells on the shaded side grow quicker and so the shoot bends towards the light.
What happens when a shoot is growing sideways?
Auxin falls to the bottom of the shoot which stimulates growth at the bottom of the shoot. This means the shoot bends upwards.
What happens when a root grows sideways?
The auxin falls to the bottom which inhibits growth in the bottom of the root. This causes the root to bend downwards.
What happens when there’s more moisture on one side of a root?
Auxin moves to the moist side which inhibits growth on the moist side. This causes the root to bend towards the moisture.
Name two ways artificial plant hormones are used in agri- /horticulture.
- Selective weed killers
* Rooting powders
How do selective weed killers work?
They are made of plant growth hormones that only work on broadleaved plants. This disrupts the broadleaved weeds’ growing patterns so they die.
