Endocrine

Question 1

what are the main functions of the endocrine systems?

Answer 1

1) Maintain body homeostasis.
2) Help the body to react to stress in concert with the nervous system.
3) Regulate growth and development, including sexual development and reproduction

Question 2

what are the main types of hormones?

Answer 2

1) Protein and glycoprotein hormones. Examples: Insulin, parathormone.
2) Small peptide hormones. Examples: vasopressin, oxytocin.
3) Hormones that are derivatives of amino acids. Examples: thyroxin, adrenalin
4) Steroids derived from cholesterol. Examples: testosterone, cortisol.

Question 3

how does the endocrine system accomplish these functions?

Answer 3

the synthesis and secretion of hormones, chemical messengers that typically are released into the blood to act at specific distant receptors

Question 4

what does the endocrine system consist of?

Answer 4

• major endocrine organs
• organs with a partial, but significant , endocrine role
• diffuse endocrine system: scattered cells within organs that fulfil an endocrine function

Question 5

what is most of endocrine tissue origin?

Answer 5

epithelial origin

Question 6

what is the exception to endocrine tissue that is not epithelial origin?

Answer 6

adrenal medulla (basically a modified sympathetic ganglion, it is derived from the neural crest), hypothalamus (part of the brain), posterior pituitary (part of the brain)

Question 7

Name 4 major endocrine glands.

Answer 7

Pituitary gland
Hypothalamus
Pineal gland
Thyroid gland

Question 8

what controls the pituitary gland?

Answer 8

hypothalamus

Question 9

why is the pituitary gland called the master gland?

Answer 9

its hormones regulate the activity of many other endocrine glands

Question 10

why does the pituitary gland sit?

Answer 10

in the sella turcica of the sphenoid bone, and is just below the hypothalamus

Question 11

what are the two lobes of the pituitary gland?

Answer 11

• anterior lobe or adenohypophysis

- posterior lobe or neurohypophysis

Question 12

how does the posterior lobe/ neurohypophysis develop?

Answer 12

downward growth of the hypothalamus and stays attached to the hypothalamus by the pituitary stalk

Question 13

how does the anterior lobe/adenohypophysis develop?

Answer 13

upward pocket of epithelium in the roof of the oral cavity called Rathke’s pouch

Question 14

Describe the hypothalamic- hypophyseal portal system?

Answer 14

a system that delivers factors to the anterior pituitary at relatively high concentration as hormone secretion in the anterior lobe of the pituitary is itself controlled by hormones from the hypothalamus above

Question 15

Describe the structure of the anterior pituitary.

Answer 15

consists of packed secretory cells interspersed with fenestrated endothelium-lined vascular sinuses. These vessels are the second capillary bed in the hypothalamic-hypophyseal portal system

Question 16

how do the secretory cells in the anterior pituitary react to dyes?

Answer 16

• Acidophils: stain with acid dyes.
• Basophils: stain with basic dyes.
• Chromophobes: take up either stain only very weakly

Question 17

what are acidophils and basophils collectively called?

Answer 17

chromophils

Question 18

Describe the structure of the posterior pituitary.

Answer 18

• consists of the axons of nerve cells in the supraoptic and paraventricular nuclei of the hypothalamus. These travel down the pituitary stalk and terminate near capillaries in the posterior pituitary
• Within the posterior pituitary there are special glial cells called pituicytes (P). Swellings in the axons, called Herring bodies (HB), represent aggregations of oxytocin or antidiuretic hormone (vasopressin).

Question 19

what is the functional unit of the thyroid gland?

Answer 19

thyroid follicle, a spherical space lined by epithelial cells that are low cuboidal when inactive

Question 20

what do the 2 main thyroid hormones do : T3 and T4?

Answer 20

regulate cell basal metabolism rate and heat production. They also have a role in development and growth

Question 21

Describe thyroid C cells.

Answer 21

C cells or parafollicular cells are found adjacent to the follicular cells. They are within the basal lamina that surrounds the follicle, but are not in contact with the colloid. They are easy to see in sections stained for their secretory product: calcitonin. Calcitonin inhibits osteoclast activity and lowers blood calcium. C cells are derivatives of the neural crest - these cells invade the thyroid during embryological development

Question 22

what produces parathyroid hormone :a polypeptide hormone that is necessary for life?

Answer 22

Usually 4 small oval glands on the posterior surface of the thyroid gland

Question 23

How does parathormone increase serum calcium by?

Answer 23

• Stimulating release of calcium from bone
• Increasing renal calcium reabsporption
• Increasing calcium absorption from the gut

Question 24

what are the 3 cell types in the parathyroid glands?

Answer 24

• principal of chief cells-secrete PTH
• oxyphils- larger eosinophilic cells
• occasional adipose cells

Question 25

what are the two different embryological origins of the two parts of the adrenal gland?

Answer 25

- The adrenal cortex is formed of epithelial cells. - The adrenal medulla is formed of neural crest cells (like the sympathetic ganglia and dorsal root ganglia). It is essentially a modified sympathetic ganglion where the postganglionic neurons have lost their axons and instead release their transmitter (adrenalin or noradrenalin) into the blood

Question 26

what is the adrenal gland surrounded by?

Answer 26

a thick capsule with connective tissue trabeculae extending inward through the cortex

Question 27

what are the 3 distinct layers or zones of the adrenal cortex?

Answer 27

From outer to inner: - Zona Glomerulosa - Zona Fasciculata - Zona Reticularis

Question 28

What are the 3 types of cholesterol-based steroid hormones secreted by the adrenal cortex?

Answer 28

1) Mineralocorticoids - involved electrolyte and fluid homeostasis 2) Glucocorticoids - involved in metabolism 3) Sex hormones

Question 29

what is the function of the adrenal medulla?

Answer 29

- reinforces the action of the sympathethic nervous system at times of stress - contain granules of adrenaline and noradrenaline that are released into the blood in response to sympathetic stimulation. This prepares the body for the ‘fight or flight’ response, increasing heart rate, raising blood pressure, causing bronchodilation

Question 30

what gland is both exocrine and endocrine?

Answer 30

pancreas

Question 31

what are the 3 principal cell types in the pancreatic islets?

Answer 31

1) Insulin secreting cells -Causes lowering of blood glucose (lack of insulin causes type I diabetes mellitus) 2) Glucagon secreting cells -Causes elevation of blood glucose (e.g. release into bloodstream from liver). 3) Somatostatin secreting cells- inhibits insulin and glucagon secretion but role is unclear

Question 32

what does the testes produce?

Answer 32

spermatozoa, but also secrete the male sex hormone testosterone

Question 33

what does the ovaries produce?

Answer 33

ova, but also secrete the female sex hormones oestrogen and progesterone