Endocrinology

Question 1

Why are hormones essential?

Answer 1

Hormones control that the body’s external and internal environments remain balanced (homeostasis). This is done in various ways throughout the body, but the concept is the same: glands release chemical messengers into the bloodstream which carries them to target organs.

Functions of hormones are:

• Homeostasis
• Growth and development
• Reproduction
• Energy metabolism
• Behaviour

Question 2

What types of releasing there are? What types of hormones? What type of receptors?

Answer 2

Types of releasing:

1. neurotransmitters
2. endocrine
   
   • non-neuronal (epinephrine; estrogen; testosterone)
   • neuronal (FSH; LH)
3. paracrine (growth factor; testosterone)
4. autocrine (estrogen)
5. juxtacrine

Types of hormone:

1. water-soluble (amines/amino-acid derived)
2. lipid-soluble (steroid)

Types of receptors:

1. Intracellular receptor
2. Membrane receptor

Question 3

What are some mechanisms to create homeostasis?

Answer 3

1. Positive Feed-forward: stimulation
2. Negative Feed-back: inhibition
3. Positive Feed-back
4. Negative Feed-forward

Question 4

What hormones are released by the hypothalamus? What do they do?

Answer 4

Hypothalamus is the organ responsible for the control and regulation of all hormones that circulate in the body, due to its hormones that control other endocrine glands.
It receive inputs from many regions of the brain, creating an area of integration between neuronal and hormonal regulation.

The hypothalamus release TRH (thyroid-stimulation hormone), CRH (corticotropin-releasing hormone) and GnRH (gonadotropin-releasing hormone).

GnRH is responsible for the stimulation of the pituitary gland, which secrete LH and FSH for both genders.

Question 5

What hormones are released by the pituitary gland? What do they do?

Answer 5

The pituitary gland is another super-organ, because its hormones regulate other endocrine glands.

1. Posterior pituitary
2. Anterior pituitary (release of LH and FSH, responsible for the stimulation of main reproductive organs in both genders)

Question 6

Where do sex hormones have effects?

Answer 6

1. Testosterone:
   
   • stimulation of spermatogenesis
   • affection of CNS function (libido)
   • stimulation of metabolism (protein synthesis, blood cell formation,
     muscle growth)
   • secondary sex characteristics (facial hair, muscle mass, body size)
   • maintain accessory glands and organs of male reproductive tract
     = baldness

Question 7

Why doctors can prescribe intake of hormones?

Answer 7

Prostaglandin E1 is prescribed as treatment for erectile dysfunction, so that Ca2+ can decrease and allow blood to flow in smooth muscles

Question 8

Is there a correlation between hormones and our appearance?

Answer 8

• Pheromones

- Androgens (lateral growth in cheekbones, chin, mandible; eyebrow ridges grow forward)

Question 9

What are some examples of steroid hormones?

Answer 9

All steroid hormones are synthesised from cholesterol.

• androgens
• estrogens
• progesterone