Week 7 - Lecture 1 - Function and Regulation of Hormones

Question 1

Characteristics of hormones

Answer 1

chemicals with various structure, from simple to complex

formed originally in tissues or organs which affect the growth and/or function of other target tissue or organs (or in some case secretory tissue)

Question 2

7 regulatory functions of hormones

Answer 2

1. energy metabolism
2. growth and development
3. muscle and fat distribution
4. fluid and electrolyte balance
5. sexual maturation
6. reproduction
7. stress response

Question 3

Features common to all hormones : control

Answer 3

hormone synthesis and release is controlled by tissues and organs

the hypothalamic-pituitary axis in the brain is an important control centre for many hormones

Question 4

Features common to all hormones : patterns

Answer 4

hormones exhibit predictable patterns of

• secretion
• metabolism
• elimination

Question 5

features common to all hormones : feedback

Answer 5

hormones listen and adjust based on negative or positive feedback loops

Question 6

features common to all hormones : action

Answer 6

hormones exhibit two primary functions

• to act on target organs to achieve an effect or
• to act on glands to produce another hormone

Question 7

features common to all hormones : receptor binding

Answer 7

to exert an effect, hormones must locate and attach onto target tissues

Question 8

The hypothalamic - pituitary axis

Answer 8

pituitary gland (hypophysis) has two major lobes

posterior pituitary
- neural tissue

anterior pituitary (Adenohypophysis) 
-glandular tissue

Question 9

The hypothalamic-pituitary axis 2

Answer 9

the hypothalamus responds to various stimuli (neurotransmitters and stressors) to produce the following hormones to transport to the pituitary:

1. hormones that act on the anterior pituitary lobe
   - prolactin

releasing hormones

• growth hormone-releasing hormone (GHRH)
• Thyrotropin-releasing hormone (TRH)
• Corticotropin - releasing hormone (CRH)
• Gonadotropin-releasing hormone

inhibiting hormones

• somatostatin (inhibits growth hormone and thyroid stimulating hormones)
• Dopamine (inhibits prolactin )

2. Hormones that act on the posterior pituitary lobes:
   Antidiuretic hormone (ADH)
   Oxytocin

Question 10

posterior pituitary

Answer 10

downgrowth of hypothalamic neural tissue

neural connection to hypothalamus (hypothalamic- hypophyseal tract)

Nuclei of hypothalamus synthesise neurohormones oxytocin and antidiuretic hormone (ADH)

Neurohormones are transported to posterior pituitary for release into the blood stream

Question 11

Anterior lobe

Answer 11

Originates as outpocketing of oral mucosa

vascular connection to hypothalamus 
- hypophyseal portal system 
 primary capillary plexus 
 hypophyseal portal veins 
 secondary capillary plexus 

carries releasing and inhibiting hormones to anterior pituitary to regulate hormone secretion

Question 12

Anterior Pituitary hormone action 1

Answer 12

the hypothalamus produces the hormone

the hormone travels to the anterior pituitary

the hormone is released unchanged into the circulation

example - prolactin

Question 13

anterior pituitary hormone action 2

Answer 13

the hypothalamus produces a releasing hormone

the releasing hormone travels to and acts upon the anterior pituitary

the pituitary is stimulated to produce and release a different hormone into the circulation

example : growth hormone

Question 14

anterior pituitary hormone action 3

Answer 14

the hypothalamus produces a releasing hormone

the anterior pituitary is activated to release a stimulating hormone

the stimulating hormone acts on the gland to produce and secrete a final hormone that tis released into the circulation

example : thyroid hormone