Chapter 4 Hormonal Communication Flashcards
What are the 2 types of hormone?
- peptide hormones
- steroid hormones
What are peptide hormones?
They are not soluble in the phospholipid membrane so do not enter the cell and need to bind to the cell surface membrane and release a second messenger inside the cell.
What are steroid hormones?
They can pass through the membrane so enter the cell and the nucleus to have a direct effect on the DNA in the nucleus.
What are some examples of peptide hormones?
- Adrenaline
- Insulin
- Glucagon
What are some examples of steroid hormones?
- Oestrogen
- Testosterone
What are endocrine glands?
Secrete hormones directly into the bloodstream
What are exocrine glands?
Secrete hormones into a duct which carries the hormone to a specific part of the body, e.g. salivary gland
What is the process following adrenaline reaching its target cell?
1.Adrenaline (1st messenger) binds to membrane receptor
2. This creates a conformational change causing the G-protein to split from the receptor
3. The G-protein becomes activated and combines with enzyme adenyl cyclase
4. Adenyl cyclase converts ATP into cyclic AMP (2nd messenger)
5. cAMP binds to and activates protein kinase
6. Protein kinase activates glycogen phosphorylase kinase which binds to glycogen phosphorylase
7. Glycogen phosphorylase catalyses the breakdown of glycogen into glucose
Which hormones are secreted by the adrenal medulla?
Adrenaline and noradrenaline
What are the 3 layers of the adrenal cortex?
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
What is the Zona glomerulosa?
The outermost layer of adrenal cortex which secretes mineralocorticoids such as aldosterone, which contributes to maintaining blood pressure
What is the Zona Fasciculata?
The middle layer of adrenal cortex which secretes glucocorticoids such as cortisol, which controls metabolism of carbohydrates, fats and proteins in the liver
What is the Zona Reticularis?
The innermost layer of adrenal cortex, which is thought to secrete precursor molecules that are used to make sex hormones.
What is the process of the action of steroid hormones?
- The hormone passes through the phospholipid membrane of target cell
- It then binds with a specific receptor (with a complementary shape) in the cytoplasm
- The receptor-steroid hormone complex enters the nucleus of the target cell and binds to another specific receptor on the chromosomal material
- Binding stimulates the production of mRNA molecules, which code for the production of proteins
What are some roles of adrenaline in the body?
- relaxing smooth muscle in the bronchioles
- increasing stroke volume of the heart
- increasing heart rate
- dilating pupils
- causing body hair to stand erect
- stimulating conversion of glycogen to glucose
What is the exocrine function of the pancreas?
Exocrine tissues synthesise and secrete pancreatic juices consisting of digestive enzymes into a duct which carries them to the small intestine.