Endocrine Tissues

Question 1

List examples of endocrine glands and their secretory products

*list all included in table

Answer 1

• APG : ACTH, LH, FSH, TSH
• PPG : Vasopressin, ADH, Oxytocin
• Thyroid gland : T3, T4
• Parathyroid gland : PTH
• Adrenal gland : corticosteroids
• Pancreas : glucagon and insulin

Question 2

What are the types of hormones?

Answer 2

• Peptide hormones : Insulin
• Steroid hormones : oestrogen

Amino Acid-Derived Hormones

• Catecholamines : Adrenaline, noradrenaline
• Thyroid Hormones : T3 and T4

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Question 3

How is Hypothalamus central to homeostasis?

Answer 3

Involed in

• Thermoregulation
• plasma osmolality
• heart rate, blood pressure
• feeding
• circardian rhythms
• stimuli from ANS
• emotion
• lactation

Question 4

What does hypothalamus produce and where do they travel?

*what route do the hormones take and which pituitary gland they end up in

Answer 4

• Vasopressin and oxytocin : travel to PPG through nerves
• 6 hormones : travel to APG via hypothalamo-hypophyseal portal system

Question 5

How does the hypothalamo-hypophyseal portal system differ from the typical circulatory route?

Answer 5

• blood passes through two sets of smaller vessels before returning to heart
• blood from first set of capillaries collects in portal vessels - branch again to supply capillary network to a second location before entering veins

Question 6

What are the hormone regulation pathways by Hypothalamus?

Answer 6

• Direct control by nervous system to Adrenal medulla
• Direct release of hormones to PPG

Question 7

What is the type of secretion involved in endocrine gland?

Answer 7

merocrine secretion

Question 8

What are the indications for Hyperthyroidism and hypothyroidism?

Answer 8

Hyper

• TSH : Low
• T4 & T3 : high

Hypo

• TSH : High
• T4 & T3 : low

Question 9

What are the indications for Hashimoto’s and Grave’s?

Answer 9

Hashimoto’s (autoimmune, hypo)

• TSH : High
• T4 : N to low
• T3 : low
• Ab’s : Anti-TPO, anti TG

Grave’s (over production of thyroid hormone)

• TSH : low
• T4 : N to high
• T3 : High
• Ab’s : TSI, anti-TSH

Question 10

What influences TSH levels?

Answer 10

• NF loop on TRH production
• TSH release at hypothalamus

Question 11

What are the histological features of thyroid gland ?

Answer 11

• Thyroid follicle
• parafollicular cells
• colloid
• epithelium

Question 12

What are parafollicular cells?

Answer 12

• neuroendocrine cells
• migrate into thyroid during thyroid development
• produce thyrocalcitonin

Question 13

What is the role of parafollicular cells?

Answer 13

• monitor plasma calcium concentrations and decreases the levels
• major effect : inhibit osteoclast activity in bone
• minor effect : inhibits renal calcium and phosphate re-absorption in tubular cells

Question 14

What is the function of parathyroid gland?

Answer 14

monitor plasma calcium concentrations

Question 15

How does parathyroid gland regulate calcium concentration?

Answer 15

• when low plasma calcium : PT gland produces more PTH

PTH causes :

• bones to release Ca2+ into blood
• absorb more Ca2+ from GIT

Question 16

What are the histological features of adrenal gland?

Answer 16

• Adipose tissue
• capsule
• cortex (zona glomerulosa, zona fasciculata, zona reticularis)
• Medulla
• blood vessel

Question 17

What are chromaffin cells and what are its functions?

Answer 17

• epithelioid cells, modified neurons
• release adrenaline and noradrenaline when nerve impuleses reach

Question 18

State the functions of zona glomerulosa, zona fasciculata and zona reticularis

Answer 18

zona glomerulosa

• produces aldosterone which regulates BP

zona fasciculata

• produces cortisone/cortisol which mobilises fats, carbohydrates and proteins (not during starvation)

zona reticularis

• produces sex steroid hormones (androgen precursors) which is used to make other sex steroid hormones

Question 19

What is the main function of adrenal cortex?

Answer 19

stress response

Question 20

What is the definition of stress?

Answer 20

A state of real or perceived threat to homeostasis

Question 21

What is the definition of stress response?

Answer 21

Maintenance of homeostais in the presence of aversive stimuli which requires activation of a complex range of responses involving endocrine, nervous and immune systems

Question 22

What are the behavioural changes and physiological adaptations in respond to stress?

Answer 22

behavioural changes

• increased awarness
• increased cognition
• enhanced analgesia

Physiological adaptations

• increased cardiovascular tone
• increased respiratory rate
• decreased vegetative functions

Question 23

What are the types of Adrenal gland responses to stress and describe them

Answer 23

Short term stress response :

• Hypothalamus sends nerve imulses to adrenal medulla through spinal chord
• chromaffin cells secrete catecholamines
• causes increase heart rate and bp, liver converst glycogen to glucose ..

Long term stress response :

• Hypothalamus releases CRH into APG
• Corticotrope cells release ACTH into blood stream and binds to adrenal cortex
• release of mineralocorticoids (causes retention of sodium and water by kidneys) and glucocorticoids (proteins and fats converted to glucose or broken down for energy)
  *

Question 24

What are the histological features of pancreas?

Answer 24

• acinar cell type
• grouped into lobules
• islet
• interlobular duct
• intercalated duct
  *

Question 25

What type of cells are intercalated duct lined with?

Answer 25

cuboidal epithelial cells

Question 26

Which cells are involved in the exocrine and endocrine function of pancreas?

Answer 26

• Exocrine : acini
• Endocrine : islets of Langerhans