Hormonal regulation
24 important questions on Hormonal regulation
What is the difference in site of mediator action between the endocrine and nervous system?
Nervous system: close to site of release (synapses)
What is the difference in types of target cells between the endocrine and nervous system?
Nervous system: muscle cells, glands, other neurons
What is the difference in time of onset between the endocrine and nervous system?
Nervous system: typically within milliseconds
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What are water soluble hormones?
- Amines (modified AA)
- Peptides
- Eicosanoids (derived from arachadonic acid)
What are lipid soluble hormones?
- Steroids (derived from cholesterol)
- Thyroid hormones (iodine added to tyrosine)
How are lipid soluble hormones transported?
What is the advantage of being bound to a transport protein?
- Transport is improved by making the hormones water soluble
- Loss of the hormone by filtration of the kidney is prevented
What is the difference in receptors for lipid soluble and water soluble hormones?
- hormones diffuse into the cell
- in the nucleus the activated receptor-hormone complex alters gene expression
- this newly formed mRNA directs synthesis of specific proteins on ribosomes.
- the hormone binds to its receptor and activate G proteins, which activate adenylate cyclase
- activated adenylate cyclase converts ATP to cAMP
- cAMP serves as a second messenger to activate protein kinases
- activated protein kinases phosphorylate other enzymes
- millions of phosphorylated enzymes catalyse reactions that produce physiological responses
- phosphodiesterase inactivates cAMP
What are steroid receptors?
What are four different hormonal interactions?
- Permissive effect
- Synergistic effect
- Antagonistic effect
- Integrative effects
What is the permissive effect of hormones, can you give an example?
Example: Thyroid hormone is required in order for epinephrine to affect energy consumption.
What is the synergistic effect of hormones, can you give an example?
Example: Estrogen and LH are both required for oocyte production.
What is the antagonistic effect of hormones, can you give an example?
Example: insulin promotes glycogen synthesis and glucagon stimulates glycogen breakdown.
What is the integrative effect of hormones?
What are the two feedback mechanisms? Can you explain them?
How are hormones released from the posterior pituitary?
How are hormones released from the anterior pituitary?
What is the function of vasopressin? What about oxytocin?
Oxytocin: regulate reproductive activities
What are circumventricular organs?
What affects vasopressin release?
- Plasma osmolarity (high plasma osmolarity --> release of vasopressin)
- Blood pressure (low blood pressure --> release of vasopressin)
What are the two different types of diabetes insipidus?
- Genetic defect of vasopressin gene
- Destruction of magnocellular neurons by tumors
Peripheral (secondary/nephrogenic) DI: inability of collecting dust cells to respond to AVP
- Genetic defect of the vasopressin V2 receptor gene
- Inability to synthesize or insert sufficient amounts of aquaporin channels
What are the four types of pancreatic islet cells? What do they secrete?
Beta cells: secrete insulin
Delta cells: secrete growth hormone - inhibiting hormone (GH-IH)
F cells: secrete pancreatic polypeptide (PP)
What is diabetes mellitus?
What is the difference between type 1 and type 2 DM?
- Insulin treatment
- FA reduce insulin sensitivity
- Associated with obesity and age
- Treated by diet (weight loss) and exercise
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