Endocrinology Flashcards
1
Q
What are the endocrine glands?
A
- Endocrine glands, are specialised organs that secrete chemical mediators (hormones) into the circulation.
- Hormones (a regulatory substance of cellular activity) act at sites remote from the site of production
- Target tissues/organs dictated by expression of receptors for the hormone
2
Q
Define
- Endocrine
- Autocrine
- Paracrine
A
- Endocrine - Act on remote tissues
- Autocrine - Mediators act on the cell where they are produced
- Paracrine - mediators act on adjacent cells
3
Q
Which processes are controlled by hormones within the body?
A
- Homeostatic mechanisms in the body
- Energy production, utilisation and storage
- Growth and development
- Reproduction
- Many others
4
Q
What are the categories of Hormones?
A
- Peptides (e.g. ACTH, Prolactin, Insulin Oxytocin)
- Glycoproteins (e.g. LH, FSH, TSH)
- Amino-derived (e.g.ThyroidHormones Thyroxine(T4))
- Steroids (e.g. Cortisol, Testosterone, Vitamin D
- Catecholamines (e.g. Adrenaline + Noradrenaline)
- Others (Fatty acid based hormones)
5
Q
Where do hormones act?
A
- Cell Surface Receptors
- Intracellular Nuclear Receptors
6
Q
How do Hormones work through Cell Surface Receptors?
A
- Proteins and amines bind cell surface receptors
- This triggers intracellular secondary messenger systems which propagate the signal into and throughout a cell
- Hormones that do this include Insulin, or Growth Hormone.
7
Q
What are some Intracellular 2nd Messenger Systems?
A
- Phospholipid systems (e.g. Insulin)
- Cyclic AMP
- Intracellular calcium
8
Q
How do hormones work through nuclear receptrors?
A
- Steroid hormones can diffuse directly into cells and bind intracellular receptors.
- The steroid-receptor complex then moves into the nucleus and activates or suppresses specific genes
- Examples of hormones that do this are Testosterone and Cortisol
9
Q
How is speed affect through the 2 different mechanisms of action?
A
Both can elicit powerful effects with very low hormones concentrations
- Protein hormones via a cell surface receptor can act very quickly (30s – 2 mins) but have shorter effects lasting minutes.
- Steroid hormones can take hours to activate a response but by altering gene expression, steroids produce morelong lasting effects.
10
Q
How is the endocrine response modulated?
A
- Sets of endocrine glands are usually organized into hierarchical loops that allow feedforward and feedback to regulate
- Can be short or long loops
- Vast majority of endocrine pathways are self limiting – incorporate some form of negative feedback loop.
11
Q
What are some major pathways in Clinical Biochemistry?
A
- Hypothalamus – Pituitary – Adrenal (HPA) axis
- Hypothalamus – Pituitary – Gonadal axis
- Hypothalamus – Pituitary – Thyroid axis
- Anti Diuretic Hormone (ADH) – water balance
12
Q
What is the hypothalamus and pituitary gland?
A
- Hypothalamus: Area of the brain involved in a wide range of homeostatic & metabolic processes. Exerts many of its effects through stimulation of the Pituitary gland.
- Pituitary Gland is divided into 2 sections/lobes.
13
Q
How does the hypothalamus communicate with the pituitary gland?
A
- Stimulates the Anterior pituitary using peptides hormones carried by capillaries.
- Stimulates the Posterior pituitary using neuronal signals.
14
Q
Which hormones are released by the anterior pituitary?
A
- Adrenocorticotrophic hormone (ACTH)
- Growth hormone (GH)
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Prolactin
- Thyroid stimulating hormone (TSH)
15
Q
Which hormones are released by the Posterior Pituitary?
A
- Antidiuretic hormone (ADH) (aka Arginine vasopressin (AVP))
- Oxytocin
