Topic 6 - Glands Flashcards

1
Q

What is a gland?

A
  • epithelial cell(s) that are specialised for the secretion of a substance
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2
Q

What are the two ways to classify a gland?

A
  1. By their structure

2. By how their products are released

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3
Q

What makes a gland endocrine?

A
  • no duct
  • secrets hormones directly into bloodstream
  • all the epithelial cells secrete the hormone in that particular gland
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4
Q

What makes a gland exocrine?

A
  • ducted (more specific/ localised delivery)
  • secretes enzymes/lubricants usually
  • only cells at the apex of the duct secrete the products
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5
Q

Give examples of endocrine glands.

A
  • Pituitary (hypothysis), thyroid, parathyroid
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6
Q

Give examples of exocrine glands.

A
  • salivary, pancreas, mammary, sweat, sebaceous, lachrymal
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7
Q

Why is it useful for some duct epithelial cells in a gland to alter their morphology and become myoepithelial cells?

A
  • then have features of both a smooth muscle cell and an epithelial cell
  • can squeeze to eject the secretions from the duct
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8
Q

What are acinae?

A
  • an acinus is a cavity at the end of a gland where all the secretory cells reside
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9
Q

What are the functions of the striated duct?

A
  • keep the ductal system open

- reabsorb sodium ions

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10
Q

What are the 3(4) ways that glands secrete products?

A
  1. Merocrine - fusion of vesicles with apical membrane before budding off (exocytosis) e.g. endocrine glands in pancreas
  2. Apocrine - the top part of the cell is pinched off and forms the secretion e.g. lactating mammary gland and external genitalia sweat glands
  3. Holocrine - Mature cell dies and becomes secretory product e.g. sebaceous gland in skin, tarsal glands in eyelid
    (4) . Cytocrine - living cells released as secretion e.g. spermatozoa is only example of this
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11
Q

Briefly explain the 2 different types of Merocrine secretion.

A
  1. Regulated Secretion - accumulation of secretory product in large vesicles and is released via exocytosis upon receiving stimulation signal. ACTIVE PROCESS, Requires Ca2+ ions and ATP to work
  2. Constitutive Secretion - Secretory product is packaged into small vesicles and continuously released to the cell surface
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12
Q

Explain Holocrine secretion.

A
  1. Secretory cell gradually fills up with secretory product (granules)
  2. Cell organelles degenerate (not enough room)
  3. Cells die
  4. Plasma membrane breaks and the contents are spilled out
  5. Dead cells are replaced by mitotically dividing basal cells
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13
Q

What is glycosylation of a protein/lipid?

And what is its role?

A
  • covalent attachment of sugars by enzymes to proteins/lipids to form glycoproteins/glycolipids
  • aids protein folding/prevents digestion by lipases or proteases/cell recognition
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14
Q

Define phagocytosis and pinocytosis.

A

Phagocytosis - The process by which cells engulf or envelop other cells/particles
Pinocytosis - process by which liquid (e.g. lipid) droplets are ingested by cells
Both are endocytosis

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15
Q

What are the 3 types of glandular control?

A
  1. Humoral
  2. Neural
  3. Hormonal
    All 3 via negative feedback loops
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16
Q

The pituitary gland, other name? Location? Hormones?

A
  1. Hypophysis
  2. Base of brain
  3. TSH (thyroid stimulating hormone), ACTH (Adrenocorticotrophic hormone), FSH (follicle stimulating hormone), LH (luteinising hormone), growth hormone, prolactin, MSH (melanocyte stimulating hormone), ADH OR vasopressin (anti diuretic hormone), oxytocin
17
Q

Thyroid gland, location? Hormones?

A
  1. Anterior to the trachea (two lobes)

2. Thyroxine (T4), tri-iodothyroinine (T3)

18
Q

Parathyroid gland, location? Hormones?

A
  1. 4 of them (2 pairs), each lies on the dorsal surface of the thyroid gland
  2. PTH (Parathyroid hormone/parathormone, parathyrin)
19
Q

Adrenal glands, location? Hormones?

A
  1. Sits atop each kidney (Cortex surrounds each medulla)

2. Corticosteroids, androgens, oestrogen, progestin

20
Q

Pancreas, location? Hormones?

A
  1. Left of and behind the stomach
  2. Exocrine = secretes digestive enzymes into duodenum
    Endocrine (islet of langerhans): alpha cells = glucagons, beta cells = insulin
21
Q

What are the two amino acid derived hormone types?

A
  • thyroid hormones (T3, T4)

- catecholamines (adrenaline, noradrenaline)

22
Q

What is described as the master conductor of the endocrine system?

A

Hypothalamus

23
Q

Explain the way the hypothalamus works with relation to hormones.

A
  • Vasopressin and oxytocin travel to posterior pituitary via nerves
  • six other hormones travel via the hypothalamo-hypophyseal portal system to the anterior pituitary in the blood
24
Q

How does a portal circulatory system differ from a normal one? And where are the only 2 portal circ systems found in humans?

A
  1. Blood travel-
    Normal: Arteries, arterioles, capillaries, venule, veins
    Portal: Arteries, arterioles, capillary bed 1, capillary bed 2, venule, veins
  2. Head: between the hypothalamus and pituitary (hypophysis)
    Abdomen
25
Q

Which gland is known as the “butterfly” gland due to its shape and appearance?

A

Thyroid gland

26
Q

What parameters will indicate hyper and hypothyroidism?

A
Hyperthyroidism = high T3/T4
Hypothyroidism = low T3/T4
27
Q

What is the function of parafollicular (in the thyroid follicle) cells (C cells)?

A
  • making calcitonin to lower calcium in blood plasma

- inhibits the action of osteoclasts (they break down bone to release calcium)

28
Q

What does the parathyroid gland do?

A
  • monitor blood plasma calcium levels
  • if blood calcium is low, they will make PTH (parathyroid hormone)
  • PTH causes the bones to release their calcium into the blood and to absorb more from the GI tract
  • negative feedback loop so once calcium levels have reached set point the glands stop producing PTH
29
Q

Why is an overactive parathyroid a big problem?

A
  • overproduction of PTH
  • high levels of blood calcium
  • calcium is involved in the electrical system for our nerves and muscles (contraction)
30
Q

What is the stress response?

A
  • When an individual is faced with homeostatic challenges, a number of behavioural and physiological changes are initiated to improve survival chances
  • Behavioural = increased awareness + cognition, euphoria, enhanced analgesia
  • Physiological = increased cardiovascular tone, respiratory rate, intermediate metabolism
  • decreased vegetative function (reproductive/feeding/digestion/growth/immunity)
31
Q

List all the cell types found in the islet of langerhans and what they secrete.

A

Alpha cells = glucagon
Beta cells = insulin
Delta cells = somatostatin (inhibits insulin and glucagon secretion)
F cells - pancreatic polypeptide