Hormonal control Flashcards
What are the two types of glands and how are they different?
Endocrine glands and exocrine glands. They differ structurally and in what they produce.
What are hormones, and where are they secreted?
Hormones are signaling proteins secreted by the endocrine glands directly into the bloodstream.
How do hormones control target cells?
1.Hormones control target cells by binding to a receptor on the target cell membrane.
2. This triggers membrane-bound reactions and stimulates the release of a second messenger.
3. The second messenger activates enzymes.
What are the types of hormones, and how are they classified?
- The types of hormones are steroid, protein and peptides, and amine.
- Steroid hormones are lipid-soluble and, cholesterol-based hormones.
- Protein and peptide hormones are water-soluble, and they are further classified into small peptide hormones (ADH and oxytocin) , protein/polypeptide, and glycoprotein.
- Amine hormones are derived from tyrosine and tryptophan, and they are either water or lipid-soluble.
What are the carrier requirements for different types of hormones?
If a hormone is water-soluble, it requires carriers to transport them through the blood.
Oestrogen and testosterone (lipid soluble) need to be carried by proteins.
Protein and Amine hormones (Insulin, adrenaline, and ADH) travel free, while thyroxine needs a carrier.
Give an example of steroid hormones
Oestrogen and Testosterone
Give an example of protein hormones
Insulin, Oxytocin, FSH
What is adrenaline, and how does it work in cellular metabolism? (diagram question)
(refer to diagram) Adrenaline is a hormone produced by the adrenal gland that readies the body for short-term emergencies.
1. Adrenaline binds to its receptor (G-protein) on a muscle cell, triggering a conversion of energy from ATP to cAMP.
2. This leads to the phosphorylation of two metabolic enzymes, glycogen phosphorylase and glycogen synthase.
3. Glycogen phosphorylase breaks down glycogen into glucose, causing a lot of energy to be released.
4. Glycogen synthase builds glycogen only when energy is not needed.
How does oestrogen work in a cell?
- Interacts with intracellular ERα and ERβ receptors
- Oestrogen binds to ERα receptor ERβ, binds tooestradiol.
- Both then join to form a dimer (two identical molecules linked together) and ERβ activates Erα
- The dimer binds to DNA at oestrogen response points in the promoter region and stimulates protein synthesis and cell proliferation
What is insulin?
- Insulin is a protein hormone produced by the pancreas that regulates blood glucose concentration
- Triggers the formation of glucose to glycogen to lower sugar levels in the blood
- Binds to receptors on the surface of cells
How does an insulin receptor work?
The insulin receptor is a transmembrane signal protein with 2 alpha and 2 beta subunits joined by disulfide bonds
The alpha subunit contains the insulin binding site, and the beta subunit has a tyrosine kinase which acts as an on and off switch for cells.
What is ADH (anti-diuretic hormone)?
- ADH is used for the homeostatic control of osmoregulation
- produced by the hypothalamus
3.increases water reabsorption and decreases water loss in the urine - It regulates the volume and osmolarity of the urine by controlling how much water is reabsorbed back into the blood
- Osmoreceptors in the hypothalamus are situated outside the blood-brain barrier and are sensitive to changes in blood water potential and osmolarity.
How does the hypothalamus regulate ADH? (diagram)
- When blood water potential drops, water moves out of osmoreceptor cells causing them to shrink. This triggers a neuronal response to increase ADH release, which raises blood water potential.
- rise in blood water potential, water moves down its osmotic gradient into the osmoreceptors causing them to swell. This triggers a neuronal response to decrease ADH release, which lowers blood water potential.
How does the hypothalamus contribute to hormones?
- The hypothalamus links the endocrine and nervous systems
- It synthesizes neurohormones into the circulation via the posterior pituitary, e.g. oxytocin and ADH
- It synthesizes releasing hormones into the hypophyseal portal blood system, which regulate hormones released from the anterior pituitary, e.g. growth hormone, follicle stimulating hormone.
What are the 6 different types of female reproductive system hormones?
- GnRH
- FSH (Follicle stimulating hormone)
- LH (luteinising hormone)
- Oxytocin
- Oestrogen
- Progesterone
