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1st Term / PHA115 > Week 19 / Endocrine system 3 > Flashcards

Week 19 / Endocrine system 3 Flashcards

1
Q

Q: What is the role of mineralocorticoids (aldosterone)?

A

A: Aldosterone is essential for life and regulates Na⁺ and K⁺ balance, as well as extracellular fluid (ECF) volume.

Principal site of action: Distal & collecting tubules of the kidney.
Action: Promotes Na⁺ retention and K⁺ excretion, leading to fluid retention and expansion of ECF volume.
Regulation: Secretion is regulated by angiotensin II (RAAS), elevated serum K⁺ levels, and ACTH (minor).

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2
Q

Q: What are the roles of glucocorticoids (cortisol)?

A

A: Cortisol plays a key role in the regulation of carbohydrate, protein, and fat metabolism.

Gluconeogenesis: Increases blood glucose levels through increased glucose production and cellular glucose uptake.

Protein metabolism: Decreases protein synthesis and increases protein catabolism in muscle, leading to the mobilization of free amino acids.

Lipolysis: Increases the mobilization and oxidation of free fatty acids.

Stress adaptation: Plays a key role in adapting the body to stress.

Anti-inflammatory & immunosuppressive effects: Exerts these effects in response to stress or injury.

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3
Q

Q: What are the roles of sex hormones (androgenic DHEA)?

A

A: Sex hormones (androgenic DHEA) supplement the sex hormones secreted by the gonads.

Minor effects on reproductive function: Have a smaller role in reproductive processes.
Physiologically significant in females:
Growth of pubic and axillary hair.
Enhancement of the pubertal growth spurt.
Development and maintenance of female sex drive.
Promotion of protein anabolism and growth.

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4
Q

Q: What is the Adrenal Medulla?

A

A: The Adrenal Medulla is a modified sympathetic postganglionic neuron.

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5
Q

Q: How is the Adrenal Medulla innervated?

A

A: The Adrenal Medulla is innervated by preganglionic sympathetic axons.

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6
Q

Q: What hormones are secreted by the Adrenal Medulla?

A

A: The Adrenal Medulla secretes Adrenaline, Noradrenaline, and Dopamine.

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7
Q

Q: What are the main functions of the Adrenal Medulla?

A

A: The main functions of the Adrenal Medulla are:

Reinforcement of “fight-or-flight” responses.
Maintenance of arterial blood pressure.
Increased heart rate, cardiac output, and respiratory rate.
Increased glycogenolysis and glucose mobilisation.
Increased lipolysis and mobilisation of free fatty acids.

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8
Q

Q: What is the Endocrine Pancreas?

A

A: The Endocrine Pancreas consists of clusters of secretory cells called Islets of Langerhans.

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9
Q

Q: What are the types of secretory cells in the Islets of Langerhans?

A

A: The Islets of Langerhans comprise three types of secretory cells:

Alpha (α) cells
Beta (β) cells
Delta (δ) cells

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10
Q

Q: What do Alpha (α) cells secrete?

A

A: Alpha (α) cells secrete glucagon.

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11
Q

Q: What do Beta (β) cells secrete?

A

A: Beta (β) cells secrete insulin.

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12
Q

Q: What do Delta (δ) cells secrete?

A

A: Delta (δ) cells secrete somatostatin.

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13
Q

Q: How are secretions from the Endocrine Pancreas regulated?

A

A: Secretions from the Endocrine Pancreas are regulated by changes in blood glucose concentration.

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14
Q

Q: What type of hormone is Insulin and what is its primary role?

A

A: Insulin is an important anabolic hormone that regulates fuel metabolism.

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15
Q

Q: How does Insulin affect blood levels of glucose, fatty acids, and amino acids?

A

A: Insulin promotes the cellular uptake and storage of glucose, fatty acids, and amino acids, which lowers their blood levels.

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16
Q

Q: What processes does Insulin enhance?

A

A: Insulin enhances:

Glycogenesis (conversion of glucose to glycogen)
Triglyceride synthesis
Protein synthesis

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17
Q

Q: What processes does Insulin inhibit?

A

A: Insulin inhibits:

Glycogenolysis (breakdown of glycogen)
Gluconeogenesis (production of glucose)
Lipolysis (breakdown of fats)
Protein degradation

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18
Q

Q: How does Insulin mediate its effects?

A

A: Insulin mediates its effects via insulin receptors, which are TK-linked (tyrosine kinase-linked).

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19
Q

Q: How does Glucagon act in relation to Insulin?

A

A: Glucagon generally opposes the actions of insulin.

20
Q

Q: What does Glucagon do to energy-rich molecules?

A

A: Glucagon mobilizes energy-rich molecules from storage sites into the bloodstream, increasing their blood levels.

20
Q

Q: What processes are promoted by Glucagon?

A

A: Glucagon promotes:

Glycogenolysis (breakdown of glycogen)
Gluconeogenesis (production of glucose)
Hepatic glucose production and release
Lipolysis (breakdown of fats)
Ketogenesis (production of ketones)

21
Q

Q: What processes are inhibited by Glucagon?

A

A: Glucagon inhibits:

Triglyceride synthesis
Protein synthesis
Protein degradation

22
Q

Q: What triggers the secretion of Glucagon?

A

A: Glucagon is secreted in response to a fall in blood glucose concentration.

23
Q

Q: Where is Parathyroid hormone (PTH) secreted from?

A

A: PTH is secreted by the parathyroid glands, which are located on the dorsal surface of the thyroid glands.

24
Q

Q: What is the primary role of Parathyroid hormone (PTH) in calcium homeostasis?

A

A: PTH is the single most important regulator of blood calcium (Ca²⁺) levels.

25
Q

Q: How does PTH raise plasma calcium levels?

A

A: PTH raises plasma calcium levels through three mechanisms:

Bone resorption — increasing the release of calcium into the blood.
Renal reabsorption — increasing calcium reabsorption in the kidneys.
Activation of vitamin D — leading to increased intestinal absorption of calcium.

26
Q

Q: How is the secretion of Parathyroid hormone (PTH) regulated?

A

A: The secretion of PTH is regulated by blood calcium levels.

27
Q

Q: How is Vitamin D (cholecalciferol) synthesized?

A

A: Vitamin D is synthesized by the skin and activated in the liver and kidneys. It can also be supplemented by dietary intake.

27
Q

Q: What is the second most important regulator of blood calcium levels?

A

A: Vitamin D is the second most important regulator of blood calcium (Ca²⁺) levels.

28
Q

Q: How does Vitamin D control plasma calcium levels?

A

A: Vitamin D controls plasma calcium levels via three mechanisms:

Increased intestinal absorption of calcium, leading to increased blood calcium levels.
Bone resorption, releasing calcium into the blood.
Decreased synthesis of parathyroid hormone (PTH).

29
Q

Q: Where is Calcitonin secreted from?

A

A: Calcitonin is secreted by the parafollicular (C) cells of the thyroid gland.

30
Q

Q: What are the effects of Calcitonin on blood calcium levels?

A

A: Calcitonin lowers plasma calcium levels by:

Decreasing bone resorption, leading to reduced release of calcium into the blood.
Decreasing renal reabsorption of calcium, leading to increased excretion and lowered blood calcium levels.

31
Q

Q: How does Calcitonin regulate blood calcium levels?

A

A: Calcitonin is a minor physiological regulator of blood calcium levels, and its secretion is regulated by blood calcium levels.

32
Q

Q: What are the gonads and what do they consist of?

A

A: The gonads are the sex organs, comprising the testes (male) and the ovaries (female).

33
Q

Q: What are the primary functions of the testes?

A

A: The testes have two primary functions:

Production of sperm (spermatogenesis).
Secretion of male sex hormones (androgens), primarily testosterone.

34
Q

Q: What are the primary functions of the ovaries?

A

A: The ovaries have two primary functions:

Production of ova (egg cells) (oogenesis).
Secretion of female sex hormones, including estrogens and progestins/progestogens (primarily progesterone).

35
Q

Q: What is testosterone and where is it secreted?

A

A: Testosterone is a male sex hormone secreted by the Leydig cells of the testes. It is converted into dihydrotestosterone (DHT) in target tissues.

36
Q

Q: When does testosterone production increase?

A

A: Testosterone production increases rapidly at puberty.

37
Q

Q: What are the key functions of testosterone?

A

A: Key functions of testosterone include:

Promoting development of male reproductive organs.

Promoting development and maintenance of male secondary sexual characteristics (e.g., facial hair, deeper voice).

Increasing and maintaining sexual drive and desire.

Increasing bone thickness and periosteal bone formation.

Increasing basal metabolic rate and muscle mass.

Promoting RBC formation and protecting against anemia.

38
Q

Q: What is oestrogen and where is it secreted from?

A

A: Oestrogen (specifically oestradiol) is secreted by the granulosa cells of the ovarian follicle.

39
Q

Q: When does oestrogen production increase?

A

A: Oestrogen production increases rapidly at puberty.

40
Q

Q: What are the key functions of oestrogen?

A

A: Key functions of oestrogen include:

Promoting maturation and maintenance of the reproductive organs in their mature functional state.

Promoting development and maintenance of female secondary sexual characteristics (e.g., breasts, pubic hair, fat distribution).

Playing critical roles, along with progesterone, in the normal female reproductive cycle (menstruation, pregnancy, childbirth).

Reducing bone resorption and increasing bone density.

Mediating important cardio- and vaso-protective effects.

41
Q

Q: What is progesterone and where is it secreted from?

A

A: Progesterone is secreted by granulosa and theca cells of the ovarian follicle.

42
Q

Q: When does progesterone production increase?

A

A: Progesterone production increases markedly during the luteal phase.

43
Q

Q: What is another name for progesterone and why?

A

A: Progesterone is called the “hormone of pregnancy” due to its critical role in pregnancy.

44
Q

Q: What are the key functions of progesterone?

A

A: Key functions of progesterone include:

Playing critical roles, along with oestradiol, in the normal female reproductive cycle.

Helping mediate sexual response in the brain.

Preparing the uterus for implantation.

Rendering the cervical canal impenetrable to sperm after implantation.

Inhibiting uterine contractions during gestation.

Inhibiting the Na+-retaining activity of aldosterone, leading to natriuresis and fluid retention.

1st Term / PHA115 (35 decks)

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