1. A quick review Sam Craik
Endocrinology
A quick review
Sam Craik

2. What is endocrinology B. Paracrine B A
The transmission of a hormone message from one cell...
Transports via the blood stream.
Arrives at a distant cell elsewhere in the body.
Triggering a response from this cell.
A. Autocrine
C. Endocrine C

3. Hormone Types - Peptide
Synthesised from one or more amino acid.
Peptides often produced as inactive pro-hormones.
Can be stored in vesicles for quick release.
Act at target’s plasma membrane.
Second messengers activated.
Rapid response.
Examples:
Serotonin (amino acid derived)
T3, T4 (dipeptide)
Insulin (polypeptide)

4. Hormone Types - Lipid
Derived from lipids: often cholesterol, sometimes fatty acids.
Cholesterol converted to pregnalone.
From here it is converted to steroid hormones.
Slow fluctuations in steroid homone levels.
Lipid soluble - Act on intracellular receptors.
This affects gene expression, slow response.
Examples:
Testosterone, Oestrogen, Progesterone.
Cortisol
Prostaglandins (Fatty Acid)

5. Anterior Pituitary Hypothalamus Ant Pituitary Target
Growth Hormone Releasing Hormone (GHRH)
Growth Hormone
Cell division + Differentiation
Thyrotropin Releasing Hormone (TRH)
Thyroid Secreting Hormone
T3 + T4 (Thyroid)
Corticotrophin Releasing Hormone (CRH)
Adrenocorticotrophin Hormone (ACTH)
Cortisol (Adrenal Cortex)
Prolactin
Lactation (Mammary)
Gonadotrophin Releasing Hormone (GnRH)
Follicle Stimulating Hormone (FSH)
Gonads
Luteinizing Hormone (LH)

6. Posterior Pituitary Oxytocin – Induction of childbirth, milk ejection.
Vasopressin – Increased water absorption in kidney.
Both are produced in the Hypothalamus and transported down a nerve axon in vesicles to the posterior pituitary where it is released into the blood. This is Neuroendocrine action. A D
D. Neuroendocrine

7. Feedback
Postive and negative feedback can occur where a hormone within a series acts back on the earlier hormones to activate or inhibit their release.
Hypothalamus
Ant Pituitary
Ovary
GnRH
FSH
Oestrogen
Hypothalamus
Ant Pituitary
Ovary
GnRH
FSH
Oestrogen
+ve Feedback
-ve Feedback

8. Growth Hormone Deficiency Excess Hypothalamus
Short Stature
Loss of growth stimulation (bone and muscle growth, fat brakdown)
Hypothalamus
Excess
Gigantism in children, excessive long bone growth.
Acromegaly in adults, epiphyseal fusion occurred already.
Growth in soft tissues and flat bones.
GHRH
Ant Pituitary
Growth
Hormone
Liver
IGF-1

9. Thyroid Hormones Deficiency Hypothyroidism Congenital
Control rate of cellular metabolism
Deficiency
Hypothyroidism
Congenital
Iodine Deficiency
Hashimotos (AI)
Tiredness
Weight Gain
Memory problems
Depression
Goitre
Hypothalamus
Excess
Hyperthyroidism
Graves Disease (AI)
Restlessness
Weight Loss
Irritability
Goitre
TRH
Ant Pituitary
TSH
Thyroid
T3 + T4

10. Glucocorticoids Deficiency Addison’s Disease
Hypothalamus
Deficiency
Addison’s Disease
Destruction of Adrenal Cortex causes reduction in production of glucocorticoids (eg: Cortisol), mineralocorticoids and sex steroids.
Often autoimmune
Sometimes Tubercolosis
Weight loss
Anorexia
Weakness
CRH
Ant Pituitary
ACTH
Adrenal Cortex
Cortisol

11. Glucocorticoids Excess Cushing Syndrome
Hypothalamus
Excess
Cushing Syndrome
Can be at hypothalmic, pituitary or adrenal level.
Cortisol has a negative feedback on ACTH.
Can use ACTH levels to detect where problem is.
High ACTH = Hypothalamus or Pituitary, excess ACTH produced.
Low ACTH = Adrenal Cortex, excess Cortisol independent of ACTH, feeds back to inhibit.
Thin limbs (fat/muscle breakdown)
Central weight gain (storage of released fats/glucose)
CRH
Ant Pituitary
ACTH
Adrenal Cortex
Cortisol