Endocrine system 1 Flashcards
What endocrine organs are located in the head/neck? (5)
Parathyroid glands Pineal gland Pituitary gland Hypothalamus Thyroid
Which endocrine organs are located in the trunk of the body? (3)
Pancreas
Adrenal glands
Ovaries/testes
What is the structure of the pituitary gland? (3)
Anterior pituitary gland - mouth (up growth from roof of mouth)
Posterior pituitary gland - neural (down-growth of the brain)
Connected by the pituitary stalk to the hypothalamus
What are the scientific names for vascularised pituitary and neural pituitary? (2)
Vascularised - adenohypophysis
Neural - neurohypophysis
What is the hypothalamus?
Cell bodies and the neurone responsible for the secretion of hypothalamic-releasing factors (hormones)
Where does a hormone initially go once released from the hypothalamus?
They pass along portal vessels to reach a capillary bed of the ANTERIOR PITUITARY which controls secretion
What is endocrine axis route? (7)
Hypothalamus Releasing hormone Anterior pituitary Tropic hormone Peripheral endocrine gland Peripheral hormone Target cell response
How does the endocrine axis adapt to change?
It contains feedback loops, direct and indirect at each stage - stays within a narrow range
What hormone produces LH and FSH (sex hormones)
Gonadotrophin-releasing hormone
What is the main function of the posterior pituitary? (2)
Store vesicles containing hormone
Release into blood when stimulated
What are the 4 key steps in the hypothalamus + posterior pituitary gland?
- Neuroendocrine cells synthesise vasopressin and oxytocin in hypothalamus
- Vesicles transported along neurones
- Stored in axon termini in posterior P
- Hormones released into the blood
What do arginine vasopressin and antidiuretic hormone do? (2)
Blood vessels - increase BP by vasoconstriction V1 receptors (high AVP conc)
Kidney - increase re-absorption of water V2 receptors (AVP) ADH increases urine production (opposite)
What is oxytocin?
Allows breast milk to come out of the breasts
Release stimulated by suckling and by cervical stimulation
What roles the PP have in oxytocin release?
Suckling/cervical distension Sensory nerves increased stimulation Hypothalamus releases hormone down the neural tract PP releases oxytocin Positive feedback cervical distension
Where is the pineal gland located?
Beneath the corpus callous and behind the thalamus
What does the pineal gland release?
Melatonin - derived from tryptophan
What is melatonin? (4)
It is involved with the control of the body’s circadian rhythm in synchrony with there light/dark cycle
- promotes sleep
- seasonal fluctuations
- important for breeding, migration, hibernation
What is the structure of the thyroid gland? (4)
Inwards to out
- Colloid centre
- Microvilli edge of centre
- Cuboidal follicular cells surrounding
- Capillary around the edge
What hormones are made in the thyroid and where are they stored? (3)
Thyroxine (T4) and tri-iodothyronine (T3)
Made and synthesised in colloid of thyroid follicules
Stored in the follicular cells
Where is calcitonin made?
Parafollicular C cells outside of the thyroid
What are the actions of T3 and T4? (2)
Increase metabolism in the body
(Increased basal metabolic rate)
(Increase metabolism of CHOs, proteins and fats
Stimulate growth and development
What does calcitonin do?
Involved in calcium homeostasis, decreases calcium ions
What are the 5 tropic hormones the anterior P produces?
GH - many tissues TSH - thyroid ACTH - adrenal cortex LH/FSH - testes and ovaries Prolactin
