The endocrine system Flashcards

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1
Q

What is the endocrine system

A

The endocrine system includes all of the endocrine cells and tissues of the body.

Glandular secretory cells surrounded by an extensive network of capillaries that allows for diffusion of hormones from cells to the blood stream

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2
Q

Where do endocrine secretory cells secrete?

A

Directly into the blood

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3
Q

What are the two different classes of hormone

A

Lipid hormones
Water soluble hormones

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4
Q

What hormones are included within the lipid hormone class

A

The lipid-soluble hormones include steroid and thyroid hormones.

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5
Q

What hormones are included in the water soluble hormone class?

A

Amine, peptide and protein hormones

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6
Q

What are the 5 changes that a hormone is able to produce?

A

➢Alters plasma membrane permeability or membrane potential, or both by opening or closing ion channels.
➢Stimulates synthesis of enzymes and other proteins within the cell.
➢Activates or deactivates enzymes.
➢Induces secretory activity.
➢Stimulates mitosis

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7
Q

Where are receptors for water soluble hormones located

A

The cell membrane

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8
Q

Where are receptors for lipid soluble hormones located?

A

Inside the cell

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9
Q

What do the hypothalamus and pituitary gland do

A

They act as a unit, regulating the activity of most of the other endocrine glands.

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10
Q

What does the hypothalamus do?

A

The hypothalamus is a small part of the brain below the thalamus. It secretes several releasing (stimulatory) and suppressing (inhibitory) hormones that regulate nearly all aspects of growth, development, metabolism and homeostasis

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11
Q

Where is the pituitary gland

A

The pituitary gland lies in the hypophyseal fossa of the sphenoid bone below the hypothalamus, to which it is attached by a stalk

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12
Q

What are the two parts of pituitary gland?

A

The anterior pituitary
The posterior pituitary

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13
Q

Where is the anterior pituitary gland

A

An UP growth of glandular epithelium from the pharynx.

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14
Q

Where is the posterior pituitary gland

A

A DOWN growth of nervous tissue from the brain.

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15
Q

What is between the hypothalamus and the posterior pituitary gland?

A

A network of fibres

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16
Q

What does the anterior pituitary gland do

A

The anterior pituitary is supplied indirectly with arterial blood that has passed through the capillaries of the hypothalamus.

As well as providing oxygen and nutrients, this blood transports releasing and inhibiting hormones secreted by the hypothalamus.
These hormones stimulate the release of several other hormones.

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17
Q

What are the anterior pituitary gland hormones? (Tropic hormones; there are 6)

(Think FSH and LH) (GCSE biology)

A
  1. Growth Hormone (Stimulates growth)
  2. Prolactin (lactating for women)
  3. Leutanising hormone (LH) (the production of testosterone in testi and secretion of progesterone and oestrogen)
  4. FSH (formation of sperm and maturation if ovary and oestrogen)
  5. TSH (Stimulates the secretion of thyroid hormones T3 & T4)
  6. Adrenocorticotropic hormone (ACTH) (synthesis and secretion of the glucocorticoid and adrenal androgens by the adrenal cortex)
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18
Q

What does the posterior pituitary gland do

A

The posterior pituitary does not synthesise hormones, but stores and releases hormones produced by the cells of the hypothalamus.

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19
Q

What hormones are released from the posterior pituitary gland?

A
  1. Vasopressin or ADH
    2.Oxytocin
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20
Q

The posterior pituitary gland does not synthesise hormones, what does it do with them instead?

A

Stores and releases hormones produced by cells of hypothalamus

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21
Q

What is there a network of between the hypothalamus and posterior pituitary gland

A

Network of fibres through which the hormones travel through

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22
Q

What is the posterior pituitary gland supplied by

A

Arterial blood

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23
Q

What is vasopressin or antidiuretic hormone? (released by the posterior pituitary)

A

a short peptide that is secreted in response to elevated plasma osmolarity (high salt or low water content) or decreased blood volume.

It acts on the kidney tubules to enhance water reabsorption from the tubular fluid and the formation of more concentrated urine (i.e., a water conservation mechanism).

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24
Q

What is oxytocin (released by posterior pituitary gland)

A

stimulates uterine (uterus) contraction during labour and the contraction of breast ducts during lactation

25
Q

Where is the Thyroid Gland and what does it look like?

A

The thyroid gland is a butterfly-shaped endocrine gland, located on the anterior surface of the neck, just below the larynx and in front of the trachea.

26
Q

How many lobes is the thyroid gland made up of?

A

2 lobes
Right and Left
Connected by isthmus

27
Q

How many arteries supply blood to the thyroid

A

Four arteries supply blood to the thyroid, two on each side, superior and inferior thyroid arteries.

•There is also extensive venous return from the gland.

28
Q

What is the structure of the thyroid gland

A

The gland is formed of small spherical sacs called thyroid follicles.

The wall of the follicle consists primarily of cuboidal epithelial cells called follicular cells that are surrounded by a basement membrane.

29
Q

The follicle cells in the structure of the thyroid gland are under effect by what hormone?

A

Thyroid Stimulating Hormone (TSH) from the anterior pituitary

30
Q

What happens when the follicle cells of the thyroid gland are stimulated

A

They secrete 2 hormones:
Thyroxine (T4)
Tri-iodothyronine (T3)

31
Q

What mainly produces T4 and what mainly produces T3

A

The thyroid gland produces mainly T4 and a smaller amount of T3.

•However, most T3 is produced from T4 outside the thyroid gland in other tissues such as liver, kidney and muscle

32
Q

What is more active T3 or T4

A

T3

33
Q

What are the main functions of T3 and T4?

A
  • Regulate growth, development and reproduction
  • Stimulate metabolic activities
  • Increase sensitivity of the cardiovascular and nervous system to adrenaline and noradrenaline (hormones that relate to acute stress)
34
Q

What cells lay between the follicle cells and what do they do?

A

C cells (parafollicular cells)
These cells secrete calcitonin which helps regulate calcium homeostasis

35
Q

What is the function of calcitonin

A

The main function of calcitonin is to lower raised blood calcium levels by promoting the storage of calcium in bone cells and inhibiting its reabsorption in kidney tubules

36
Q

What are parathyroid glands

A

Two pairs of tiny rounded masses of tissue embedded in the posterior surfaces of the thyroid gland are called parathyroid glands.

•One superior and one inferior parathyroid gland are attached to the right and left thyroid lobes.

37
Q

The parathyroidal glands contain two different type of epithelial cells, what are they?

A

Chief cells (more of them) produce parathyroid hormones (PTH)

The function of the other type is not known

38
Q

What is the main function of parathyroid hormone (PTH)

A

Increase blood calcium levels

(This is achieved by increasing the calcium absorption from the small intestine and calcium reabsorption from the kidney tubules. It also releases calcium from bones into the blood by stimulating osteoclasts (bone-destroying cells)

39
Q

Parathyroidal hormone (PTH) and calcitonin maintain calcium levels which is important for: (MTBN)

A

Muscle contraction
Transmission of nerve impulses
Blood clotting
Normal action of enzymes

40
Q

What and where are the adrenal glands?

A

The glands are composed of two parts that have different structures and functions. The outer is the cortex, and the inner part is the medulla.

Connective tissue covers the gland. The adrenal glands, like the thyroid gland, are highly vascular

41
Q

The adrenal cortex is subdivided into three zones that secrete three types of steroid hormones, what are these 3 zones called?

A

➢The outer zone secretes mineralcorticoids.
➢The middle zone secretes glucocorticoids
➢The inner zone secretes sex hormones

42
Q

What are secreted by the adrenal cortex

A

•Weak sex hormones (mainly androgens) are secreted, in small amounts, by the adrenal cortex in both males and females

43
Q

What is the main mineralocorticoid and what does it do

A

Aldosterone, maintains water and electrolyte balance.

44
Q

What stimulates the secretion of aldosterone from the adrenal cortex?

A

High blood potassium levels stimulate the secretion of aldosterone from the adrenal cortex.

45
Q

What are glucocorticoids and what do they include:

A

Cortisol (the main one)
Corticosterone
Cortisone

46
Q

What are the effects of glucocorticoids (Cortisol, Corticosterone, Cortisone)

A

-Glucose formation
-Lipolysis (breakdown of fat)
-Stimulation of breakdown of proteins
-Promoting sodium and water reabsorption by kidney tubules
-Anti inflammatory actions
-Suppression of immune response
-Delayed wound healing

47
Q

What is the adrenal medulla and what does it do

A

When stimulated by an extensive sympathetic stimulation, the adrenal medulla releases hormones - adrenaline (epinephrine) about 80% and noradrenaline (norepinephrine) about 20%

48
Q

Adrenaline and noradrenaline that is released by the adrenal medulla initiate fight or flight, name some symptoms of this:

A

➢Increasing heart rate.
➢Increasing blood pressure.
➢Diverting blood to essential organs including the heart, brain and skeletal muscles, by dilating their blood vessels and constricting those of less essential, such as the skin.
➢Increasing metabolic rate.
➢Dilating the pupil

49
Q

what is Pancreatic islet and what does it do

A

The pancreas is both an endocrine gland and an exocrine gland.

The acini produce digestive enzymes that are secreted into the GIT through the pancreatic duct.

50
Q

What are the 4 cell types found in the pancreatic islet?

A

➢Alpha or A cells (about 17%) that secrete glucagon.
➢Beta cells or B cells (about 70%) that secrete insulin.
➢Delta cells or D cells (about 7%) that secrete somatostatin.
➢F cells (about 6%) that secrete pancreatic polypeptide

51
Q

Delta/D cells in the pancreatic islet secrete somastatin, what does somastatin do

A

Glucagon raises the blood glucose level, and insulin lowers it. Somatostatin inhibits the secretion of both insulin and glucagon in addition to inhibiting the secretion of growth hormone (GH) from the anterior pituitary.

52
Q

What are the main effects of insulin

A

1.To enhance the useful utilisation of glucose by various organs and tissues for the purpose of oxidation and energy generation.
2.To increase glycogenesis (formation of glycogen from glucose, glycogen is branched chains composed of repeated glucose units)
3.To accelerate protein synthesis (formation of proteins from amino acids).
4.To accelerate lipogenesis (synthesis of fatty acids).
5.To decelerate glycogenolysis (conversion of glycogen to glucose).
6.To decelerate gluconeogenesis (formation of glucose from lactic acid and amino acids).

53
Q

What are the 3 most important insulin antagonists:

A

1.Glucagon
2.Adrenaline
3.Cortisol

54
Q

What are gonads and what do they produce

A

Male and female sex organs
Produce gametes (sperm and oocytes in females)

55
Q

What is the thymus

A

The thymus is a bilobed gland embedded in a mass of connective tissue inside the thoracic cavity, usually behind the sternum.

56
Q

What does the thymus do

A

The thymus produces several hormones, collectively known as thymosins, which play a role in the development and maintenance of normal immunological responses.

57
Q

The thymus promotes the maturation of what type of lymphocyte

A

They promote the maturation of T-lymphocytes,

58
Q

Where is the pineal gland

A

The pineal gland is a small body attached to the third ventricle of the brain at the midline and it is part of the epithalamus.

59
Q

What is the main hormone of the pineal gland

A

Melatonin is the main hormone of the pineal gland.