Functional anatomy and physiology Flashcards
What does the endocrine system consist of?
pituitary gland, thyroid, parathyroid, adrenal
glands, pancreas, ovary and testes
What are the 4 classes of hormones?
- Peptides
- Amines
- Iodothyronines
- Cholesterol derivatives and steroids
How are water soluble hormones transported?
Unbound to proteins
How do water soluble hormones interact with cells?
Bind to surface receptor
What is the half life of water soluble hormones?
Short
How quickly is the clearance for water soluble hormones?
Fast
What are examples of water soluble hormones?
Peptides, monoamines
How are lipid soluble hormones transported?
Protein bound
How do lipid soluble hormones interact with cells?
Diffusing into cells
What is the half life of lipid soluble hormones?
Long
How quickly is the clearance for lipid soluble hormones?
Slow
What are examples of lipid soluble hormones?
Thyroid hormones, steroids
Are peptides / monoamines stored?
Yes stored in vesicles
Are steroids stored?
No synthesised on demand
Describe features of peptide hormones
- Peptides vary in length
- Can be linear or ring structures and can bind to carbohydrates
- Peptide hormones can be used as granular store
What is the process of the synthesis of peptide hormones?
Synthesis: preprohormone –> prohormone
Packaging: Prohormone –> hormone
Storage: hormone
Secretion: hormone
Describe features of amine hormones
Water soluble, stored in secretory granules, release pulsatile, rapid clearance
Describe features of iodothyronines
- Thyroid hormones are not water soluble
- 99% is protein bound
- Only 20% of T3 in the circulation is secreted directly by thyroid
- Secretory cells release thyroglobulin into colloid – acts as base for thyroid hormone synthesis
- Incorporation of iodine on tyrosine molecules to form iodothyrosines
- Conjugation of iodothyrosines gives rise to T3 and T4 and stored in colloid bound to thyroglobulin
- T3 and T4 are
cleaved from thyroglobulin when TSH stimulates the movement of colloid into secretory
cell
Which type of hormone has receptors on cell membranes?
Peptide
Which type of hormone has receptors mainly in cytoplasm?
Steroid
What are some examples of steroid hormones who’s receptors are in cytoplasm?
Glucocorticoids (cortisol)
Mineralocorticoids (aldosterone)
Androgens (testosterone)
Progesterone
Which type of hormone mainly has receptors in the nucleus?
Thyroid
Which hormones have receptors in the nucleus?
Oestrogen
Thyroid hormone
Vitamin D
What are the different types of cholesterol derivatives and steroid hormones?
- Vitamin D
- Adrenocortical and gonadal steroids