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Body Logistics > Session 5 - Glands > Flashcards

Session 5 - Glands Flashcards

1
Q

Define a gland

A

An epithelial cell or an aggregation of epithelial cells that are specialised in the secretion of a substance

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2
Q

How do you classify different types of glandular tissue?

A

1) Where the products are secreted: Endocrine or exocrine

2) What the mode of secretion is: Merocrine, Apocrine or Holocrine

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3
Q

Explain the differences between endocrine and exocrine glands

A

Endocrine glands secretes hormones directly into the blood. Exocrine glands secrete their products into a location via a duct

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4
Q

Define Merocrine secretion and give an example

A

Secretion through exocytosis. Fusion of vesicles with apical surface (insulin)

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5
Q

Define Apocrine secretion

A

The partial loss of cytoplasm due to the non-membrane bound compounds gathering at the apical surface and as such pushing on it (mammory glands)

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6
Q

Define Holocrine secretion

A

The complete loss of the cytoplasm or cell (sebaceous glands)

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7
Q

Define Cytocrine secretion

A

Cell released as secretion (spematid)

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8
Q

Describe how glands are formed

A

1) Growth signal received (FGF growth factor)
2) Proliferation of cells occurs and extracellular protein degradation enzymes are released
3) Epithelial cells invade space created
a) 4) Exocrine gland - Central cells die of to produce duct (canaliculisation). 2 Cell types produced: glandular and ductal
b) 4) Endocrine gland - Produce angiogenic factors to stimulate blood vessel growth in and around the epithelial cells
b) 5) Endocrine gland - Link to surface is broken through apoptosis

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9
Q

How does branching of glands occur during development?

A

1) tubule elongation (growth factor 1 active, 2 not)

2) tubule branching (growth factor 2 active, 1 not)

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10
Q

Name all 8 types of exocrine ductal morphology and give an example of each.

A

Simple tubular - Intestinal glands
Simple coiled tubular - sweat glands
Simple branched tubular - Gastric glands
Simple alveolar - Not common, one in end of penis
Simple branched alveolar - sebaceous glands
Compound tubular - duodenal glands of small intestine
Compound alveolar - Mammary glands
Compound tubuloalveolar glands - Salivary glands

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11
Q

What is a myoepithelial cell and what is their role?

A

Cells that feature features of both an epithelial cell and a smooth muscle cell
They help to eject secretions from the duct (by squeezing the top section)

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12
Q

What order do the ducts follow?

A

Acinus - where the product is secreted

1) Intercolated Duct
2) Striated Duct - Reabsorbs Na+ ions
3) Excretory Duct - sometimes has smooth muscle around it
4) Collecting Duct - not very common normally excretory duct is last

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13
Q

Explain the development of the breast

A

1) initial development the same as the salivary but stops until puberty
2) Puberty - oestrogen and progesterone produced by the ovaries restarts breast development
oestrogen - ductal elongation
progesterone - side branching
3) during pregnancy prolactin stimulates the production of breast secretions (colostrum and milk)
prolactin - Alveologenesis and lactogenic differentiation

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14
Q

What are the two modes of merocrine secretion?

A

Regulated - secretory granules accumulate and are released upon stimulation
Constitutive - continuously released. Vesicles often have plasma proteins associated to them to repopulate the cell membrane

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15
Q

Describe in detail the process of regulated merocrine secretion.

A

This is an active process

1) vesicles are packaged with contents
2) active secretion requires specific signal (Ca2+ ions)
3) Vesicle migrates to the cell surface along microtubules (this uses energy hense why it is an active process)
4) In the presence of Ca2+ ion, membrane of vesicles fuses with plasmalemma
5) contents released into the intercellular space

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16
Q

Define Glycosylation

A

The covalent attachment of a sugar to a protein or lipid by an enzyme. This usually occurs in the Golgi apparatus

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17
Q

What is the difference between phagocytosis and pinocytosis?

A

Phagocytosis is where cells engulf other cells or particles where as pinocytosis is the process where liquid droplets are ingested by cells. (they are both forms of endocytosis)

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18
Q

Name the 4 types of trans-epithelial transport.

A

1) paracellular - transport via aqueous channels between cells via tight junctions
2) transcellular- transport of lipid soluble molecules that pass through the membranes
3) Carrier proteins into and out of the cell
4) Endocytosis and then exocytosis

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19
Q

what are the 4 types of glandular control?

A

Humoral control - feedback loop though endocrine system
Nervous control - via innervation of nerves
Hormonal control - Hormonal secretions
Neurocrine control - eg: hypothalamus and pituitary. Neurotransmitter enters the blood stream and then travel to stimulate target cell

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20
Q

Why is PTH essential to life but calcitonin isn’t?

A

PTH is essential as it regulates the concentrations of Vitamin D for calcium absorption from the diet. If this wasn’t present I.E. no Parathyroid gland then we wouldn’t be able to absorb Calcium. Calcitonin only reduces calcium levels so is important to prevent seizures but not essential

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21
Q

Name the 5 major endocrine glands and tissues

A 
Pituitary (anterior and posterior)
Thyroid
Parathyroid
Adrenal Glands
Pancreas
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22
Q

Where is the pituitary gland located and what does it secrete?

A

It is found at the base of the brain
Anterior: TSH, ACTH, Gonadotrophins (FSH, LH, GH (growth hormone)).
Posterior: ADH (vasopressin), Oxytocin

23
Q

Where is the thyroid gland located and what does it secrete?

A

It is found anterior to the tranchea

It secretes T4 and T3

24
Q

Where is the Parathyroid gland located and what does it secrete?

A

Dorsal to the thyroid, 4 glands 2 pairs on each lobe

PTH

25
Q

Where is the adrenal gland located and what does it secrete?

A

It is found on the top of the kidneys
It secretes Cortex: Coticosteroids, small amounts of androgen, oestrogen and progesterone.
Medulla: Catecholamines (adrenaline and noradrenaline)

26
Q

Where is the pancreas located and what does it secrete?

A

It is located left of and behind the stomach
It has both endo and exocrine function and so secretes
Endocrine: Islets of langerhans, Glucagon and insulin
Exocrine: digestive enzymes secreted into the duodenum

27
Q

Name 4 types of hormones

A

Glycoproteins/Peptide hormones
Steroid hormones
Catecholamines
Thyroid hormones

28
Q

Where are glycoprotein/ peptide hormones synthesised and stored. How are they transported. Where are their receptors and and what is the cellular response. Give some examples?

A

Synthesis and storage - made in advance (glycosylated in the Golgi apparatus) and stores in secretory vesicles
Transport in the blood - Dissolved in blood plasma
Location of receptor - Cell membrane
Response - Activation of second messenger; may activate genes
Examples - Insulin, Glucagon, Prolactin

29
Q

Where are steroid hormones synthesised and stored. How are they transported. Where are their receptors and and what is the cellular response. Give some examples?

A

Synthesis and storage - Synthesised on demand from precursors (primarily cholestrol)
Transport in the blood - Bound to carrier proteins like albumen in the blood
Location of receptor - Cytoplasm or nucleus; some have membrane receptors too
Response - Activation of genes
Examples - Oestrogen, Androgens

30
Q

Where are Catecholamine hormones synthesised and stored. How are they transported. Where are their receptors and and what is the cellular response. Give some examples?

A

Synthesis and storage - Made in advance and stored in vesicles
Transport in the blood - Dissolved in plasma of the blood
Location of receptor - Cell membrane
Response - Activation of the 2nd messenger systems
Examples - Adrenaline and noradrenaline

31
Q

Where are thyroid hormones synthesised and stored. How are they transported. Where are their receptors and and what is the cellular response. Give some examples?

A

Synthesis and storage - Made in advance; precursor stored in secretory vesicle
Transport in the blood - Bound to carrier proteins
Location of receptor - Nucleus
Response - Activation of genes
Examples - T4 and T3

32
Q

Give some examples of how the hypothalamus is central to homeostasis and name some hormones that are secreted

A

Involved in:
Thermoregulation, Plasma osmolality, heart rate, blood pressure, feeding, satiety (had enough to eat), lactation
hormones secreted: Vasopressin (ADH), Oxytocin, 6 hormones to anterior via hypothalamo-hypophyseal portal system

33
Q

What are the two main lobes of the pituitary and how are they connected to the pituitary?

A

Anterior lobe - Connected via the portal system from the hypothalamus
Posterior lobe - connected via direct innovation from nerves. The hormone is synthesised in the hypothalamus and is transported down the nerve and as such it acts as a Neurocrine system

34
Q

Define a portal system and give 2 examples

A

The system of blood vessels that has two distinct groups of capillary beds.
Hepatic portal
hypothalamo-hypophyseal portal system

35
Q

Why is there always a small concentration of hormones from the hypothalamus and the pituitary gland in the blood?

A

All hormones released in here are subject to both regulated and more crucially constitutive merocrine secretion.

36
Q

Describe the embryonic development of the endocrine system

A

Starts in week 5+

1) pituitary develops from neurohypophyseal bud and hypophyseal pouch
2) Thyroid develops from the floor of pharynx - 2nd pouch
3) Parathyroid and thymus develop from 3rd and 4th pharangeal pouches
4) pancreas from the foregut
5) Adrenals from the intermediate medoderm and neural crest

37
Q

describe the thyroid and where it is found

A

butterfly shaped and located just below the larynx and anterior to the trachea

38
Q

define hyper and hypothyroidism

A

high T3 or 4 = hyper

low T3 or T4 = hypo

39
Q

describe how TSH levels are regulated

A

TRH is released from the hypothalamus and enters the portal system where it stimulated the release of TSH which in turn stimulates the release of thyroid hormones. These then increase the blood concentration which is sensed by the hypothalamus and inhibits TRH secretion and as a result TSH secretion.

40
Q

What levels of TSH, T4, T3 and antibodies indicates hyperthyroidism?

A

Low TSH (as it’s production is being inhibited by high T3 and 4 but thyroid is over producing)
High T3 and 4
No antibodies

41
Q

What levels of TSH, T4, T3 and antibodies indicates hypothyroidism?

A

High TSH (as it’s production is being increased by low T3 and 4 but thyroid is under producing)
Low T3 and 4
No antibodies

42
Q

What levels of TSH, T4, T3 and antibodies indicates Hashimotos?

A

High TSH, Normal to low T4 and low T3.

Anti-TPO and Anti-TG are present in blood

43
Q

What levels of TSH, T4, T3 and antibodies indicates graves?

A

Low TSH, Normal to high T4 and high T3.

TSI and anti-TSH present in the blood

44
Q

What is the role of the parafolicular cells and where are they found?

A

They are found in the thyroid and release calcitonin in response to high plasma calcium levels
calcitonin:
- inhibits osteoclast activity, renal reabsorption of calcium and counteracts PTH

45
Q

What is the role of the parathyroid hormone?

A

monitors plasma calcium levels:

- low = release of PTH which increases osteoclast activity and absorbs more calcium from GI tract

46
Q

Why is Calcium important?

A

Calcium is important in the nervous, muscular and skeletal systems. It allows for electrical control of the muscular contraction and also is needed for bone structure. As such in high concentrations it can lead to seizure and rigor

47
Q

Describe what the role of adrenal medulla is

A

composed of chromaffin cells and is innervated directly by presynaptic myelinated sympathetic nerves and as such when stimulated releases catecholamines such as adrenaline and noradrenanline

48
Q

name the layer of the adrenal cortex in order from outside to the medulla and outline there role

A

Outer - Zona Glomerulosa - Aldosterone regulates blood pressure
Middle - Zona Fasciculata - Glucocorticoids mobilises fats, proteins and carbs.
Inner - Zona Reticularis - Androgen Precursors (DHEA)

49
Q

Define stress

A

a state of real or perceived threat to homeostasis

50
Q

Outline the 3 main responses in fight or flight

A

Ramping up blood pressure
Dumping glucose into the blood
Shutting down non-emergency services

51
Q

Where are the principle stress responses localised?

A

Hypothalamus
anterior lobe of pituitary
adrenal gland

52
Q

Describe how the adrenal gland has 2 responses to stress (short and prolonged)

A

Short - Hypothalamus innervates spinal cord and spinal cord innervates adrenal medulla. Which releases catecholamines
Prolonged - Hyothalamus releases CRH, anterior pituitary senses CRH and releases ACTH into blood. This targets adrenal cortex and releases mineralocorticoids and glucocorticoids

53
Q

Name some endo and exocrine products of the pancreas

A

Endocrine - Insulin, Glucagon, Somatostatin (inhibits insulin and glucagon)
Exocrine- Trypsinogen (pro enzyme for proteases), Lipase and Amylase

Body Logistics (12 decks)

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