Endocrine Physiology Flashcards
What are the 7 functions of the endocrine system?
Respiration
Metabolism
Reproduction
Sensory Perception
Movement
Sexual development
Growth
What are the three things involved in the endocrine system?
- The regulated secretion of hormones
- The diffusion of the hormone to the vasculature
- Binding to a specific receptor within cells of a target organ
What are the three types of hormonal pathways?
Autocrine signalling
Paracrine signalling
Endocrine signalling
What is autocrine signalling?
When the same cell releases and receives the hormones
What is paracrine signalling?
When hormones are released and received by adjacent cells
What is endocrine signalling?
When hormones have to travel long distances
What are the three ways hormones act on target cells?
- Rate of enzymatic reactions
- Ion and molecular transport across the membrane
- Gene expression and protein synthesis
What is the cellular mechanism of action?
Hormones must bind to target cell receptors
What are the three ways to terminate hormone action?
- Limiting the secretion of hormone feedback loops
- Remove or inactivate the hormone in the circulation
- Terminating the activity of the hormone in target cells
What are the three major structural classes of hormones?
- Amino acid derivatives
- Peptides
- Steroids
What does the type of hormone it is affect?
Distribution, type of receptor it binds to and function
What are amino hormones?
A hormone derived from a single amino acid
What are peptide hormones?
A hormone derived from multiple amino acid linked to form an amino acid chain
What are steroid hormones?
A hormone derived from the lipid cholesterol
What is unique about peptide and amine horomoes?
They are hydrophilic and can be packaged and stored until needed in vesicles
What is unique about steroid hormones?
They are lipophilic and must travel to target cells bound to a transport protein
How do peptide and amine hormones enter target cells?
Cannot enter directly due to being hydrophilic hence must combine with a membrane receptor
How do steroid hormones enter target cells?
Enter via concentration gradient by diffusion
Why is it important that steroid hormones bind to a carrier?
It protects it from enzymatic degradation and the carrier protein will remain outside of the cell as they are lipophobic
What is hypersecretion?
When there is an excess level of hormone
What is hyposecretion?
When there is hormone deficiency
What is abnormal responsiveness of target tissue?
When the correct amount of hormone is produced and distributed but the target tissue is unable to respond to it
What are some causes of hypersecretion?
Benign or cancer tumors or exogenous application
What are some causes of hyposecretion?
Genetics, diet deficiencies, immunological or removal of gland/tissue
