The Nervous System and Menstrual Cycle Flashcards
How are messages passed along the nervous system
By electrical signals called impulses
What does the nervous system do
It controls how we react to our surroundings and our behaviour
What are the 5 sense organs and the receptors found there
Ears- sound Eyes- light receptors Tongue - taste receptors Skin- touch,change in temperature Nose-smell
What is stimuli
Changes in the environment that trigger receptors
What are receptors
Cells that are able to pick up changes in the environment
What are neurones and nerves
Neurones are special cells that pass along impulses
Lots of them together are nerves
What are sensory neurones
Special cells that carry the impulses from the sense organs to the CNS
What is the CNS
The brain or the spinal cord were the impulses are sent to be directed to the right effector organ
What are motor neurons
Neurons that carry impulses away from the CNS towards the effector organ
What happens at the effector organ
If it a muscle it contracts if it is gland it secretes
What is the order of a response in the nervous system
Receptor - sensory neurone-CNS- Motor neurone- effector
What is a reflex
A fast and automatic response to stimuli
What happens in a reflex arc
- A receptor picks a stimuli,such touching a hot plate
- Electrical impulses are sent from that receptor to the sensory neurone
- From there the impulses are sent to the relay neurone which is normally the spine
- the impulses are transported via the motor neurones to the effector organ
- there the effector organ contracts and a response Is your hand moving away from the plate
What is a synapse
It is a junction in which two neurones meet
What happens at a synapse
At one neurone sacs containing chemicals is transfused from over the space and attached on to the surface of other neurone then the impulses continues
Why in a reflex arc do the impulse bypass the conscious parts of the brain
The unconscious parts of the brain are bypassed so the reflex can happen quickly as the time between the stimuli and reaction is reduced
Name the stages of the reflex arc
Stimuli-receptor - sensory neurone-relay neurone -motor neurone-effector-response
What is the difference between the reflex arc and normal response
Reflex arc bypasses conscious parts of the brain and is quicker, normal uses the brain
What are hormones
Chemical substances that control functions in our body, they are made and secreted in glands and they are transported in the blood
What are the differences between nerves and hormones
Nerves- they are work fast
Work for a small amount of time
Act on a specific area
Hormones-slow in action
They have long lasting effects
Have an effect all over the body
What are the stages in the menstrual cycle
The uterus begins to thicken and strengthen to support a baby
Half way through a mature egg is released
If it comes in contact with sperm it may fertilise and form an embryo
If it dosent then the uterus line along with the egg break apart and shed and leads to the period
What 3 hormones are important for the cycle
FSH,LH and oestrogen
Which gland produces FSH and LH
The pituary gland in the Brain
Where is oestrogen produced
In the ovaries
What does FSH do in the cycle
It causes eggs to mature in the ovaries and causes the ovaries to produce oestrogen
What does oestrogen do in the menstural cycle
Oestrogen strengthens the lining of the uterus, inhibits the production of FSH and stimulates the pituary gland to produce LH
What does LH do in the cycle
It causes ovulation the release of one mature egg
What do oral contraceptives contain and what effect to they have on pregnancies
They contain oestrogen which inhibits the production of FSH which stops eggs maturing preventing pregnancies
What are the positives of oral contraceptives
They help prevent in unwanted pregnancies
Help prevent some cancers
What are the cons of oral contraceptive s
They must be taken regularly or artificial hormone level drops and pregnancy may occur
Sideffects-such as headaches,nausea
Don’t prevent STDs
What does proestrogene do to prevent pregnancies
It produces thick mucus across the cervix to prevent sperm from entering although not as effective as oral contraceptive a
How can the chances of pregnancies increase
FSH can be injected into women with low levels of them so eggs can mature
IVF
Name the cons of increasing chances of the pregnancies
The treatments don’t always work and are expensive
More the one egg may be mature and can result in multiple births
Describe the stages in IVF
- Ripe eggs are collected from a women uterus
- They are placed in a special solution and placed in a Petri dish
- They are mixed with sperm
- After time they are checked to see if any embryos have formed.
- If so they are 1 or 2 embryos are placed back in the woman’s womb and to see if an baby is formed
What is homeostasis
The body having a constant internal environment
What organ helps regulate water and ion levels
The kidneys
What things in the body must be kept constant
Ion level
Temperature
Sugar level
Water
How is the ion level regulated
It is taken into the body by foods, it is lost sweat, excessive is removed from the blood by the kidneys and then released as urine
How is water regulated in the body
It is taken in by food and drink
It’s lost via sweating from the skin
Breathing from the lungs
And from urine
How does weather or active participation affect homeostasis
In colder weather, more urine than sweat is produced and it is mainly waste
In hot weather or when doing lots of activity, more sweat is produced and along with urine is concentrated as it cools is down
Why is temperature important in homeostasis
37 degrees is the temperature at which our enzymes work at their best, that’s why when we are to hot we sweat as it cools us down and lowers temperature and when we are cold we shiver to increase body temperature
How is blood sugar regulated
Sugar(glucose) passes in our bloodstream from food that has entered the gut
It’s lost through normal metabolism and vigorous exercise
Insulin produced by the pancreas helps regulate blood sugar
