Endocrine Tissues Flashcards
List examples of endocrine glands and their secretory products
*list all included in table
- APG : ACTH, LH, FSH, TSH
- PPG : Vasopressin, ADH, Oxytocin
- Thyroid gland : T3, T4
- Parathyroid gland : PTH
- Adrenal gland : corticosteroids
- Pancreas : glucagon and insulin
What are the types of hormones?
- Peptide hormones : Insulin
- Steroid hormones : oestrogen
Amino Acid-Derived Hormones
- Catecholamines : Adrenaline, noradrenaline
- Thyroid Hormones : T3 and T4
How is Hypothalamus central to homeostasis?
Involed in
- Thermoregulation
- plasma osmolality
- heart rate, blood pressure
- feeding
- circardian rhythms
- stimuli from ANS
- emotion
- lactation
What does hypothalamus produce and where do they travel?
*what route do the hormones take and which pituitary gland they end up in
- Vasopressin and oxytocin : travel to PPG through nerves
- 6 hormones : travel to APG via hypothalamo-hypophyseal portal system
How does the hypothalamo-hypophyseal portal system differ from the typical circulatory route?
- 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
What are the hormone regulation pathways by Hypothalamus?
- Direct control by nervous system to Adrenal medulla
- Direct release of hormones to PPG
What is the type of secretion involved in endocrine gland?
merocrine secretion
What are the indications for Hyperthyroidism and hypothyroidism?
Hyper
- TSH : Low
- T4 & T3 : high
Hypo
- TSH : High
- T4 & T3 : low
What are the indications for Hashimoto’s and Grave’s?
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
What influences TSH levels?
- NF loop on TRH production
- TSH release at hypothalamus
What are the histological features of thyroid gland ?
- Thyroid follicle
- parafollicular cells
- colloid
- epithelium
What are parafollicular cells?
- neuroendocrine cells
- migrate into thyroid during thyroid development
- produce thyrocalcitonin
What is the role of parafollicular cells?
- 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
What is the function of parathyroid gland?
monitor plasma calcium concentrations
How does parathyroid gland regulate calcium concentration?
- when low plasma calcium : PT gland produces more PTH
PTH causes :
- bones to release Ca2+ into blood
- absorb more Ca2+ from GIT
What are the histological features of adrenal gland?
- Adipose tissue
- capsule
- cortex (zona glomerulosa, zona fasciculata, zona reticularis)
- Medulla
- blood vessel
What are chromaffin cells and what are its functions?
- epithelioid cells, modified neurons
- release adrenaline and noradrenaline when nerve impuleses reach
State the functions of zona glomerulosa, zona fasciculata and zona reticularis
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
What is the main function of adrenal cortex?
stress response
What is the definition of stress?
A state of real or perceived threat to homeostasis
What is the definition of stress response?
Maintenance of homeostais in the presence of aversive stimuli which requires activation of a complex range of responses involving endocrine, nervous and immune systems
What are the behavioural changes and physiological adaptations in respond to stress?
behavioural changes
- increased awarness
- increased cognition
- enhanced analgesia
Physiological adaptations
- increased cardiovascular tone
- increased respiratory rate
- decreased vegetative functions
What are the types of Adrenal gland responses to stress and describe them
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)
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What are the histological features of pancreas?
- acinar cell type
- grouped into lobules
- islet
- interlobular duct
- intercalated duct
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