5.4 Hormonal Communication Flashcards
What are the two types of hormones?
Peptide hormones and steroid hormones
Describe peptide hormones.
Small and charged amino acid based hormones. They are not lipid soluble so cant enter the cell but only bind to receptors on the cell membrane.
Give 3 examples of peptide hormones.
- adrenaline
- insulin
- glucagon
Describe steroid hormones.
Lipid soluble hormones that can enter the cell directly.
What are the two types of glands?
Endocrine and Exocrine
What is the difference between endocrine glands and exocrine glands?
Endocrine glands secrete the hormones directly into the blood but exocrine glands secrete the hormone into a duct that carries the hormone to a specific part of the body.
Why do peptide hormones need a secondary messenger?
The peptide hormone is the primary messenger, but as it cant enter the cell, it needs to activate a secondary messenger within the cell.
Describe the action of a peptide hormone acting on a cell.
- hormone binds to the specific receptor on the cell membrane and activates the g-protein
- g-protein activates enzyme adenyl cyclase
- adenyl cyclase converts ATP into cyclic AMP
- cyclic AMP is the secondary messenger
- cAMP will then act on another protein or initiate a chain of enzyme controlled reactions
Where are the adrenal glands?
One on top of each kidney
Which part of the adrenal gland produces peptide hormones and which produces steroid hormones?
The adrenal cortex produces steroid hormones and the adrenal medulla secretes peptide hormones.
What hormones does the adrenal medulla produce?
Adrenaline and Noradrenaline
What is the role of adrenaline?
To prepare the body for activity such as increasing heart rate and dilating pupils.
What are the 3 areas of the adrenal cortex?
- zona glomerulosa (outermost)
- zona fasciculata (middle)
- zona reticularis (inner)
Which area of the adrenal cortex produces mineralocorticoids such as aldosterone to control absorption of ions in the kidneys therefore controlling blood pressure?
Zona glomerulosa
Which area of the adrenal cortex produces glucocorticoids such as cortisol to control the metabolism in the liver in response to stress or low blood glucose levels?
Zona fasciculata
Which area of the adrenal cortex produces precursor molecules that are converted into sex hormones?
Zona reticularis
Describe the action of steroid hormones on a cell.
- steroid hormones pass through the cell membrane as they are lipid soluble
- the steroid hormones then binds to a specific receptor within the cell
- the hormone receptor complex enters the nucleus
- it then binds to another specific receptor complex on the chromosomal material of the nucleus
- this stimulates the production of mRNA which codes for protein synthesis
What are the two roles of the pancreas?
- to aid digestion by producing pancreatic juices (exocrine)
- to regulate blood sugar levels by secreting insulin and glucagon (endocrine)
Why is the production of pancreatic juices exocrine?
Because they are secreted from the pancreatic duct to the small intestine
What are pancreatic juices made of?
- digestive enzymes (lipase, protease and amylase)
- water (as a solvent)
- sodium hydrogencarbonate (to neutralise the acidity in the stomach)
What is an acinus?
A group of pancreas cells.
What are many acini grouped together?
A lobule
What is the endocrine tissue of the pancreas
Islets of langerhans
What are the two types of cells in the islets of langerhans?
a-cells (on outside) and b-cells (on inside)
