week nine - Homeostasis

Internal conditions need to be kept steady. THe balance is refered to as homeostasis.

Things that need to be kept in balance:

Water - In sweat, vapour, urine, faeces

Temperature - Maintains the optimum temperature for processes / emzymes

Ions - Managed by the kidneys - Calcium, chloride, copper

Blood Glucose - controlled by the pancreas.


Hormones
One of the body's system of communication

Nervous system:
-Electrical impulses
-Chemicals
-Neurones

Hormones:
-Chemicals
-Travel in blood
-Slow
-Released from (endocrine) glands indirectly to Target Organs


The menstrual cycle.

1.Folicle stimulating hormone (FSH) is produced in the pituitary gland

2. It eventually gets to the ovaries where it causes an egg to mature in ovary

3. the process causes oestrogen to be released in response, makes its way to pituitary gland to confirm.

4. the Pituitary gland then releases Leuterising Hormone (LH) This causes the matured egg to be released from the ovary.


Looking at this process gives us some clues about fertility and contraception

FSH is given in fertility treatment to increase the likelyhood of conception
This treatement causes many eggs to mature > multiple births

Contraception
In contraception, FSH is inhibited. Oestrogen is given to block and stop FSH

Excess oestrogen can have side effects:

Greater risk of breast cancer
It can be difficult to restart cycle if should conception become desirable

For women with history of breast cancer in the family, progesterone is an alternative to oestrogen.

Week Eight - Nervous system

The nervous system and hormones enable us to respond to external changes. They also help us to control conditions inside out bodies. THe menstual cycle is controlled by hormones.

- The nervous system enables humans to react to their surroundings and coordinate their behaviour.

- Receptors detect stimuli which include light, sound, changes in position, chemicals, touch, pressure, pain and temperature.

- Information from receptors passes along cells (neurons) in nerves to the brain. The brain coordinates the response - but not in reflex response.

- Reflex actions are automatic and rapid. THy often involve sensory, relay and motor reurons.

Internal conditions which are controlled include:

-The water content of the body -water leaves the body via the lungs when we breathe out, via the skin when we sweat, and excess water is lost via the kidneys in urine.

-The ion content of the body - Ions are lost via the skin when we sweat and excess ions are lost via the kidneys in the urine.

-Temperature - to maintain the temperature at which enzymes work best

-Blood sugar levels - to provide the cells with a constant supply of energy.


Reflex action. such as: blinking, sneezing, pupil dilation, knee jerk.

Stimulus > Sensory Neuron > Relay neuron > Motor Neuron

Between each neuron there is a gap, a synapse, neuro-transmitter passes this gap via active transport. The more frequent the stimulus, the more frequent the electrical signal and greater neuro-transmitter.