The Endocrine System Flashcards
Define homeostasis
State of dynamic equilibrium, has mechanisms to counteract changes in the internal environment so it can remain stable and constant
Why is homeostasis important
Failure Leads to disease
Describe positive feedback
Response enhances original stimulus so continues to reinforce the original stimulus e.g. an action potential
Describe hormones
Chemical signals produced by endocrine glands or tissues
Travel via the bloodstream to its target cells/tissues/organs
What are the 4 chemical classes of hormones
Peptide/polypeptide (water soluble)
Amino acid derivatives (amines)
Glycoproteins (water soluble)
Steroids (lipid soluble)
Identify the ten major endocrine glands
Hypothalamus, pineal, pituitary, parathyroid, thyroid, thymus, adrenal, pancreas, testis, ovary
Identify the 4 mechanisms of communication of hormones
Autocrine, paracrine, endocrine, neurocrine
Describe autocrine communication
Hormone triggers a response in same cell that it’s secreted in
Describe paracrine communication
Hormone signal carried to adjacent cells over a short distance via tissue fluid
Describe endocrine communication
Hormone released into bloodstream to target cells
Describe neurocrine communication
Hormones originated in neurone and after travelling down axon it’s released into the bloodstream to target cells
How hormones travel
Travel via the bloodstream
Bind to a specific protein/receptor on the target cell
How is hormone secretion controlled
Rate of production (synthesis and secretion)
Rate of delivery (more blood flow to an organ will deliver more hormone)
Rate of degradation (hormones are metabolised and excreted from body)
The difference in water soluble hormones and lipid soluble hormones
Water- bind to cell surface receptors
Lipid- bind to intracellular receptors
Describe the relationship between the hypothalamus and pituitary gland (anterior and posterior)
Form a complex functional unit that serves as the major link between the endocrine and nervous systems
