Question

(a) A full explanation of the role of the endocrine and nervous systems in maintaining homeostasis.

(b) A detail explanation for both recessive and dominant genetic disease inheritance. Please answer this two question

Answer 1

A) Endocrine System maintain homeostasis by releasing hormones to regulate metabolism and body temperature.

Nervous System maintain homeostasis through sympathetic nervous system that sends signals to the other systems, when there is danger and the parasympathetic nervous system tells systems when turn the warning.

The sensory information passed from neurons to the hypothalamus. When hypothalamus detects a homeostatic imbalance then it gives signals to the pituitary gland to release hormones in the blood stream. These hormones will act on cells carrying specific receptors for these hormones.

For example:

1) When there is loss of water then hypothalamus sends signals to pituitary gland to secrete antidiuretic hormone (ADH). This hormones reaches kidney cells to cause reabsorption of urine and secretion of a more concentrated urine so that water is preserved.

2) Body temperature changes are detected by receptors in the skin and relayed to the hypothalamus through sensory neurons. When skin temperature drops below optimum level then hypothalamus sends signals to the pituitary gland to release thyroid-stimulating hormone (TSH). TSH is carried through blood stream to the thyroid gland that binds to specific TSH-receptors. Then thyroid releases thyroid hormone, that increases metabolic rate of all cells and cause generation of bodily heat.

There are many other examples but the principle is that peripheral sensory cells detect changes in homeostasis and the information through sensory neurons passed to the hypothalamus that gives signals to the pituitary gland to release a hormone that can induce appropriate responses in peripheral organs.

B) Genetic diseases are caused by mutations in a single gene. These inheritance can be recessive and dominant depending on the gene involved:

1) Autosomal dominant

When one mutated copy of the gene then there is autosomal dominant inheritance.
An affected person inherits the condition from an affected parent. Condition can also be from a new mutation in the gene and occur in people with no family history of disorder.  

For example :
Huntington disease, Marfan syndrome

2) Autosomal recessive : when both copies of the gene has mutations. The parents of an affected individual carry one copy of the mutated gene, but will not show signs and symptoms of the condition.
For example:
cystic fibrosis, sickle cell disease