Endocrine System Flashcards
1
Q
what is the endocrine system + what is it’s functions ?
A
- specialised ductless glands
- secrete hormones into the bloodstream
- response involved in metabolism, growth or reproduction
2
Q
what are the 2 divisions of the endocrine system ?
A
- central endocrine glands
- peripheral endocrine glands
3
Q
3 central endocrine glands
A
- pituitary glands
- hypothalamus
- pineal gland
4
Q
4 peripheral endocrine glands
A
- thyroid glands
- adrenal glands
- endocrine pancreas
- parathyroid glands
5
Q
what is the function of parathyroid glands ?
A
- regulate level of calcium in the blood
6
Q
what is the role of the thyroid gland ?
A
- regulate metabolism
7
Q
what is the function of the adrenal gland ?
A
- help trigger fight or flight response
8
Q
what is the function of the pineal gland ?
A
- secretes melatonin (hormone of darkness)
- promotes sleep
- influences reproductive activity
- located in the diencephalon in the brain
- production stimulated by SCN (biological clock)
9
Q
what is the function of the pancreas ?
A
- regulated blood glucose levels by producing glucagon + insulin
10
Q
what is the function of the pituitary gland ?
A
- master gland
- secretes many different hormones which can effect other glands
11
Q
function of the endocrine system
A
- cellular metabolism
- cell growth, development, reproduction
- adaptive changes
- control circulatory and digestive system
12
Q
chemical classification of hormones in the endocrine system ?
A
- amines, amino acids
- polypeptides, proteins, glycoproteins
- steroids
- hydrophilic vs lipophilic
13
Q
what is the most common type of hormone in the body?
A
- peptide hormone
14
Q
how and where are peptide/protein hormones synthesised?
A
- by the vesicle-mediated pathway
- synthesised in rER + packaged in vesicles
15
Q
how and where are steroid hormones synthesised?
A
- non-vesicle mediated pathway
- synthesised is sER + directly released
16
Q
what hormones use free + unbound transport ?
A
- amine/peptide hormones
17
Q
what hormones use protein carrier-bound transport ?
A
- steroid + thyroid hormones
18
Q
Hormone Secretion & Regulation
A
timing/pattern
- Pulsatile/Cyclical: Hormones are released in bursts
- Diurnal/Circadian Rhythm: Hormones follow daily or 24-hour patterns
negative-feedback control
- end-product inhibition
19
Q
what are the types of hormone receptors?
A
- nuclear/intracellular
- cell surface receptors
20
Q
what is hyposecretion ?
A
- The endocrine gland secretes too little of its hormone
- types = primary,secondary,tertiary
21
Q
what is hyper-secretion ?
A
- The endocrine gland secretes too much of its hormone.
- types = primary, secondary,tertiary
22
Q
what is abnormal target cell responsiveness + 2 types?
A
- Changes in target cells that affect how they respond to hormones.
- Receptor Down-Regulation (Hyporesponsiveness)
- Receptor Up-Regulation (Hyperresponsiveness):
23
Q
Where are the hypothalamus and pituitary glands located?
A
- the hypothalamus and pituitary glands are located in the diencephalon of the brain.
-the pituitary gland lies in a pocket of bone at the base of the brain.
24
Q
What is the function of the hypothalamus and pituitary glands?
A
- function cooperatively as the ‘master regulators’ of the endocrine system.
- control critical homeostatic and metabolic functions.
25
What are the two lobes of the pituitary gland and their functions?
- Anterior Pituitary (Adenohypophysis): Secretes and releases 6 major hormones.
- Posterior Pituitary (Neurohypophysis): Stores and releases 2 hormones.
26
what is the function of the hypothalamus?
- brain's coordinating centre for endocrine, behavioural, and autonomic nervous system functions
27
How does the hypothalamus act as a neuroendocrine transducer?
- receiving and integrating multiple brain signals.
- converting signals into chemical messages.
-releasing chemical messengers (hormones) to control the secretion of pituitary hormones.
-pituitary hormones control the activity of peripheral endocrine glands.
28
What are hypothalamic releasing hormones?
- hormones produced by the hypothalamus that stimulate the release of other hormones from the anterior pituitary
29
How do hypothalamic releasing hormones affect the anterior pituitary?
- releasing hormones are sent to the anterior pituitary, which then releases its stored tropic hormones into the systemic circulation
30
How are hypothalamic releasing hormones transported to the anterior pituitary?
- action potentials trigger the release of hormones into the portal vessels, which carry them to the anterior pituitary
- where they stimulate the release of tropic hormones.
31
what is the role of Growth Hormone (GH)?
- important role in intermediary metabolism
32
what are the effects of Growth Hormone (GH) on metabolism?
- Anti-insulin effects:
- Increases lipolysis = leading to free fatty acid (FFA) mobilization and use as fuel.
- Inhibits peripheral cellular glucose uptake = increases blood glucose levels and reduces the use of glucose as fuel.
33
What regulates the secretion of Growth Hormone (GH)?
- GHRH (Growth Hormone-Releasing Hormone) and somatostatin from the hypothalamus.
- Ghrelin from the gastric fundus.
34
How is Growth Hormone (GH) output related to growth?
- GH output increases with size to maintain the concentration of GH pulses needed to sustain growth during childhood.
35
What factors influence GH secretion?
- nutritional state
36
What other hormones are involved in physical growth?
- Thyroxine
- Sex steroids
37
What happens if there is undersecretion + overproduction of (GH)?
- dwarfism
- gigantism
38
what happens if there is overproduction of Growth Hormone (GH) after maturity?
- after maturity, overproduction of GH causes acromegaly.
39
what is the role of Follicle-Stimulating Hormone (FSH) in ?
- stimulates the growth and development of ovarian follicles and promotes the ovarian secretion of oestrogen
– promotes ovarian secretion of oestrogen (F)
– Required for sperm production (M)
– Secretion stimulated by GnRH from the hypothalamus
40
what is the role of Luteinizing hormone (LH)?
– Responsible for ovulation & development of the corpus luteum
(F)
– Regulates ovarian secretion of sex hormones (F)
– Stimulates testes to secrete testosterone (M)
– Secretion stimulated by GnRH from hypothalamus
41
what is the role of prolactin (PRL) ?
- enhances breast development & milk production in females;
elevated in pregnancy and lactation
– Overproduction leads to infertility
– Secretion inhibited by DA from hypothalamus (drugs
dopamine antagonist)
42
what is the role of Thyroid-stimulating hormone (TSH) ?
- Stimulates secretion of thyroid hormones
– Promotes vascularisation & growth of the thyroid gland
– Secretion stimulated by TRH from hypothalamus
43
what is the role of adrenocorticotropic hormone?
– Stimulates secretion of cortisol by adrenal cortex
– Controls growth of the adrenal cortex
– Secretion stimulated by CRH from hypothalamus
– Inhibiting pain/stress signal
44
what are the 6 anterior pituitary hormones?
- Luteinizing hormone (LH)
- Follicle-stimulating hormone (FSH)
- Adrenocorticotropic hormone (ACTH)
- Growth Hormone (GH)
- Thyroid Stimulating Hormones (TSH)
- Prolactin (PRL)
45
what are the 2 types of posterior pituitary hormones ?
- vasopressin
- oxytocin
46
what is the role vasopressin ?
– Antidiuretic hormone (ADH)
– Controls water balance in the body
– Promotes renal water re-absorption = regulation of plasma volume & osmotic pressure
47
what is the role of oxytocin?
– Stimulates uterine contraction during childbirth & milk
ejection during breast-feeding
– Secretion inhibited by DA from hypothalamus
48
Melanocyte-Stimulating Hormone (MSH)
- Structure: Similar to ACTH.
- Role in Animals: Regulates skin pigmentation by stimulating melanocytes and controls sodium excretion.
- Mechanism: α-MSH binds to the MC-1 receptor on melanocytes, activating tyrosinase, which is required for melanin synthesis.
- Human Significance: Mutations in the MC-1 receptor are linked to people who tan poorly
49
location of thyroid gland ?
- located in the neck below lathe rynx
- 2 lobes of endocrine tissue joined by a narrow strip of gland (isthmus)
50
what are the 2 cell types of the thyroid gland ?
- foliicular cells = Secrete Tetra-iodothyronine (T4/thyroxine) and Tri-iodothyronine (T3), both iodine-containing hormones.
- parafollicular cells =secrete calcitonin
51
4 functions of thyroid hormone ?
- effect on normal growth + CNS Development
- effect on metabolic rate + heat production
- effect on intermediary metabolism
- effect on sympathetic activity
52
What is the effect of thyroid hormone on normal growth and CNS development?
- Mediates normal growth through GH and IGF-1.
- Stimulates GH secretion and hepatic production of IGF-1.
- Promotes protein synthesis and skeletal growth via GH & IGF-1.
- Required for normal nervous system development in infants and children
- promotes normal CNS activity in adults.
53
What is the effect of thyroid hormone on metabolic rate and heat production?
- Increases basal metabolic rate and heat production (calorigenic effect).
- Main regulator of resting O2 consumption and energy expenditure.
54
How does thyroid hormone affect intermediary metabolism?
- Biphasic effects on carbohydrate, fat, and protein metabolism.
55
How does thyroid hormone affect sympathetic activity?
- Increases cellular responsiveness to catecholamines through β-receptor upregulation.
56
What are the two main components of the adrenal glands?
- Adrenal Cortex (outer layer)
Adrenal Medulla (inner layer)
57
What 3 steroid hormones are secreted by the adrenal cortex?
- Mineralocorticoids (e.g., aldosterone)
- Glucocorticoids (e.g., cortisol)
- Sex hormones (e.g., DHEA)
58
What hormones are secreted by the adrenal medulla?
- The adrenal medulla secretes catecholamines, including adrenaline (AD) and noradrenaline (NA)
59
What is the role of mineralocorticoids (aldosterone)?
- helping maintain Na+ and K+ balance
- regulate extracellular fluid (ECF) volume.
60
What are the functions of glucocorticoids (cortisol)?
- Carbohydrate, protein, and fat metabolism
- Stress adaptation
- Anti-inflammatory and immunosuppressive effects
61
What are the functions of sex hormones (DHEA) from the adrenal glands?
-Supplements sex hormones secreted by the gonads
- Exerts minor effects on reproductive function
- Promotes protein anabolism and growth
62
HPA Axis and Feedback System (body's response to stress, pain, trauma etc)
- Hypothalamus releases CRH (Corticotropin-Releasing Hormone).
- CRH triggers the anterioir pituitary gland to release ACTH (Adrenocorticotropic Hormone).
- ACTH stimulates the adrenal cortex to release cortisol
- targets tissues
63
what is the main function of the adrenal medulla ?
- reinforces fight or flight
main functions:
- inc respiratory rate
- inc glycogenolysis = increased glucose mobilisation
- inc lipolysis = increased mobilisation of free fatty acids
64
what are the 3 types of cells in the islet of Langerhans ?
- α - gulcagon
- β - insulin (binsulin)
- δ (delta) - somatostatin
