1. Endocrinology Introduction Flashcards
What are the 2 categories of hormones?
Steroids (fat-soluble) OR Non-Steroids (water-soluble)
Give an example of a fat soluble hormone.
Steroids e.g. cortisol.
Are fat soluble hormones stored in vesicles or synthesised on demand?
Fat soluble hormones e.g. steroids are synthesised on demand.
What are steroid hormones made of and where?
Made of cholesterol
Made by the adrenal glands and the gonads
Where in a cell are steroid cell receptors located?
Steroid cell receptors are located in the cytoplasm.
Give examples of non-steroid hormones.
Peptides e.g. insulin, glucagon, TRH, LH, FSH
Proteins/Amino acid hormones from the AA, Tyrosine
e.g. thyroid hormones, adrenaline, noradrenaline
How do water soluble hormones e.g. peptides get into a cell?
They bind to cell surface receptors.
Where in a cell are peptide cell receptors located?
Peptide cell receptors are located on the cell membrane.
Are water soluble hormones stored in vesicles or synthesised on demand?
Water soluble hormones e.g. peptides are stored in vesicles.
Name the glands involved in the endocrine system.
- Hypothalamus
- Pituitary glands - anterior and posterior
-Thyroid and parathyroid glands - Adrenal glands
- Gonads
Describe and structure of the hypothalamus and the pituitary gland.
Hypothalamus: paraventricular + supraoptic nuclei
Hypothalamus -> Pituitary stalk -> Pituitary glands
Pituitary glands -> 1) Anterior lobe - glandular tissue
2) Posterior lobe - axons from 2 nuclei
What are the 2 categories of hormones released by the hypothalamus? State the hormones released.
**Stimulatory: **
~ Thyrotropin releasing hormone -> TRH
~ Corticotropin releasing hormone -> CRH
~ Gonadotropin releasing hormone -> GnRH
~ Growth hormone releasing hormone -> GHRH
and
Inhibitory:
~ Growth homrone inhibiting hormone AKA Somatostatin -> GHIH
~ Prolactin inhibiting factor AKA Dopamine
Give an example of an amine hormone.
Noradrenaline and adrenaline.
Give 5 ways in which hormone action is controlled.
- Hormone metabolism.
- Hormone receptor induction.
- Hormone receptor down-regulation.
- Synergism e.g. glucagon and adrenaline.
- Antagonism e.g. glucagon and insulin.
Where is the thyroid gland located?
Anteriorly in the neck at the level of C5-T1 vertebrae;
Deep to the sternothyroid and sternohyoid muscles
Describe the shape of the thyroid
- 2 lobes: left and right
- Lobes united over the trachea by a thin ‘Isthmus’ (usually anterior to the 2nd + 3rd tracheal rings)
- H-shaped appearance
- Some have a 3rd lobe!
- Covered by a fibrous capsule
- Covered by deep cervical fascia
Where are the parathyroid glands located?
Medial half of the posterior surface of each lobe of the thyroid gland inside its fibrous sheath.
Superior parathyroid glands:
- Inferior border of the cricoid cartilage
Inferior parathyroid glands:
- Inferior poles of the thyroid gland
Where do the parathyroid glands develop from?
Inferior parathyroid -> 3rd Dorsal pharyngeal pouch
Superior parathyroid -> 4th Dorsal pharyngeal pouch
How are the parafollicular cells (C-cells) of the thryroid gland developed?
4th pharyngeal pouch -> Ventral -> Ultimopharyngeal body -> C-cells
Where does the thyroid gland develop from?
From the endoderm at the base of the tongue, independent of the pharyngeal apparatus.
Descends down the neck; parathyroid glands latch on; cells from the ultimopharyngeal body migrate + join it; continues to rest at the base of the neck
What layer of the trilaminar disc is the anterior pituitary derived from?
Ectoderm (Rathke’s pouch).
What is the posterior pituitary derived form?
The floor of the ventricles.
What is the anatomical connection between the hypothalamus and the anterior pituitary gland?
Hypothalamo-hypophyseal-portal system
- A system of tiny capillaries that moves hormones quickly from the hypothalamus to the anterior pituitary.
