What is a half-life?
The time it takes for a hormone to reach half of its original concentration
What are the 3 locations of secretion?
Glands, Endocrine cells, Neurons
What is local control?
Restricted to one tissue. Local change = local response
What is reflex control?
Throughout body, by nervous or endocrine system. A change is counteracted by changes in the brain.
Target cells are always ___ from secretion locations.
Far
What do hormones regulate?
Metabolism, temperature, water balance, reproduction, growth
Where are hormones secreted?
From almost all tissues of the body.
What are pheromones?
Hormones secreted into external environment that change behaviour of others of the same species.
What are the 3 receptor locations? And which are fast/slow?
Cell surface (fast), in the cytosol (slow), in the nucleus (slow)
What are the 3 classifications of hormones?
Peptides, steroids and amines
What are the characteristics of peptides?
- lots of amino acids
- lipoPHOBIC
- short half-life
- cell-surface receptors
ex. insulin
What are the characteristics of steroids?
- derived from cholesterol
- lipoPHILIC
- long half-life
- intracellular receptor (most change in gene expression and synthesis of proteins)
ex. cortisol
What are the 2 types of amine hormones? Which one is lipophobic/lipophilic?
Catecholamines (lipoPHOBIC), thyroid (lipPHILIC)
Which endocrine reflex involves neurons?
Complex endocrine reflex
Explain primary hyperthyroidism and what is its name?
Grave’s disease. Antibodies mimic TSH activate thyroid, causing too much TSH to be released.
Explain secondary hyperthyroidism.
A tumour on thyroid or pituitary gland causes excess stimulation.
Explain primary hypothyroidism.
Lack of iodine in diet, iodine is needed for the production of thyroxine.
Explain secondary hypothyroidism and what is its name?
Hashimoto’s. Autoimmune destruction of thyroid.
Explain primary hypercortisolism and what is its name?
Cushing’s syndrome. Tumour on adrenal gland.
Explain secondary hypercortisolism and what is its name?
Cushing’s disease. Tumour on pituitary gland.
What is the cortisol pathway?
CRH (hypothalamus) - ACTH (anterior pituitary) - CORTISOL (endocrine target) - TARGET CELLS (non-endocrine target)
What is the thyroid hormone pathway?
TRH (hypothalamus) - TSH (anterior pituitary) - T4 (thyroid)
What are 3 ways a goiter will form?
Iodine deficiency, Grave’s disease, Hashimoto’s
How are goiters formed?
- Overstimulation of the thyroid gland (thyroid making too much thyroxine)
- Pituitary sending too much TSH
- Not enough iodine to form thyroxine
