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Endocrine System Flashcards

1
Q

What does the endocrine system produce?

A

various secretions:
- hormones
- hormonally active substances

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2
Q

Where do hormones and hormonally active substances go?

A
  • enter the circulatory system
  • transport to target cells
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3
Q

What classes are hormones and hormonally active substances divided into?

A

Peptides:
- insulin
- GH
- ACTH

Steroids:
- gonadal
- adrenocortical steroids

Amino Acids / Arachidonic Acid Analogs:
- catecholamines
- prostaglandins

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4
Q

What is the function of the endocrine system?

A
  • coordinates cell activities (organelles and tissues)
  • maintains homeostasis
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5
Q

What are endocrine glands?

A

Glands whose major function is to secrete hormones.

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6
Q

State the endocrine part of the pancreas.

A

endocrine
exocrine- digestion (duct –> enzyme secretion)

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7
Q

What is the difference between endocrine and exocrine glands?

A

endocrine glands: no ducts! (secrete is always hormones!) released into circulatory system!
exocrine glands: has a duct system!

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8
Q

What is a different name used to describe the pituitary gland?

A

hypophysis

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9
Q

What two parts is the pituitary gland composed of?

A

1) Anterior Lobe (adenohypophysis):
- glandular epithelial tissues consisting of 3 parts: pars distalis, intermedia and tuberalis.

2) Posterior Lobe (neurohypophysis):
- neural secretory tissue
- developed from the neuroectoderm of the CNS

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10
Q

What is the anterior lobe of the pituitary gland made up of? Other name?

A

anterior lobe = adenohypophysis
GLANDULAR EPITHELIAL TISSUES
- pars distalis
- pars intermedia
- pars tuberalis

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11
Q

What is the posterior lobe of the pituitary gland made up of? Other name?

A

posterior lobe = neurohypophysis
NEURAL SECRETORY TISSUE
- developed from the neuroectoderm of the CNS

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12
Q

State the overall key points about the pituitary gland.

A
  • small gland
  • attached to the inferior surface of the brain
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13
Q

What similarities do the two pituitary lobes share?

A

rich capillary network (necessary for picking up secreting hormones)

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14
Q

Which part of the anterior lobe glandular epithelial cells is most histologically important? Why?

A

pars distalis: produces most hormones

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15
Q

State the histological composition of the pituitary gland.

A
  • connective tissue stroma (supporting parenchymal cells) (between secretory cells)
  • secretory cells
  • secretory granules in pars distalis are identified as basophils (10%), acidophils (40%) and chromophobes (50%)
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16
Q

How are cells in the pars distalis of the pituitary gland identified? Into what?

A
  • based on staining reactions

endocrine cell secretory granules:
- basophils (10%), (blue - hematoxylin)
- acidophils (40%) (dark red - eosin dye)
- chromophobes (50%) (orange/clear - (dye)phobia)

impossible to depict which cell produces which hormone!

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17
Q

What makes up most of the posterior lobe of the pituitary gland? Other name?

A

Pituitary gland = hypophysis
- extention of the CNS

Axons (projecting from the neuron cell bodies in the supraoptic and paraventricular nuclei of the hypothalamus) make up most of the posterior lobe.

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18
Q

What is the function of the pituitary gland?

A

releases hormones

produced in the supraoptic nuclei of the hypothalamus:
- antidiuretichormone [ADH]
- vasopressin

paraventricular nuclei of the hypothalamus:
- oxytocin

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19
Q

Where are hormones produced for the pituitary gland?

A

in the hypothalAmus

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20
Q

What is the greatest difference between the anterior and posterior lobes of the hypophysis?

A

anterior lobe: produces hormones (secratory epithelial cells);
posterior lobe: stores hormones and releases them at specific times.

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21
Q

What is another name used for the Epiphysis Cerebri?

A

pinneal gland

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22
Q

What is the epiphysis surrounded by?

A

pia mater capsule

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23
Q

State the composition of the epiphysis cerebri.

A

Pinealocytes:
- primary cells
- large
- basophilic cells
- round nuclei
- secrete melatonin (association with circadian rhythms)

Astrocytes:
- interdigitate between the pinealocytes and capillaries
- astocyte like neuroglial cells (metabolism associated)

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24
Q

What is the stroma of the epiphysis cerebri based on?

A

pia mater

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25
What is a special structural component found in the epiphysis cerebri? What is its function? What is it composed of?
**Corpora Arenacea**: - intercellular *calcium* deposits - associated with *aging* (accumulate with age) - do not seem to affect glandular function. - *light-sensitive* endocrine organ is responsible for the production of **melatonin** and **serotonin**. - histological importance: helps indicate the specific location of the epiphysis cerebri | known as "brain sand"
26
What is the thyroid gland surrounded by?
**connective tissue capsule**: - fine septa between the follicles
27
State the arrangement of the parenchyma of the thyroid gland.
- **spherical follicles** - surrounded by a *dense capillary network*
28
State the histological composition of the thyroid gland.
(1) surrounded by a **connective tissue capsule** (fine septa b/w follicles). (2) **parenchyma** arranged in *spherical follicles* (size varies with activity) - size of follicles varies with activity - epithelium of follicles consists of **follicular lining cells ** (*squamous* - *columnar*) - *acidophilic* lining with numerous **cytoplasmic secretory vesicles**, a **basal nucleus** and **microvilli** (apical surface). (3)*surrounded* by a **dense capillary network**. squamous- no hormone production | columnar- hormone producting
29
What is a specific feature of the thyroid gland?
Usually glands are made up of a homogenous mass, yet the thyroid gland has **follicles** (spherical structure compartments).
30
What is the function of follicular cells? Where does this process take place?
produce **thyroid hormones** *T4* and *T3*. synthesis takes place in: - **follicular cells** - **lumen** of the follicle.
31
What is the function of parafollicular cells?
produce **calcitonin** (calcium level regulation).
32
State the composition of the follicle lumen.
Lumen is filled with a *gellike mass* called **colloid**, which contains **thyroglobulin**, an *inactive* storage form of *thyroid hormones*.
33
State the location of the parafollicular cells. How can they be depicted? Other name?
Parafollicular cells = C cells Location: - **outside** the **follicular lining epithelium** - **do not** extend to the lumen of the follicle. Depiction: - **lighter** staining - **larger** - **oval** in shape
34
What is an additional structure surrounding all glands?
rich network of blood vessels!
35
What are the two cells present in the thyroid gland?
- follicular cells (in the follicle) - parafollicular cells (near follicles)
36
State the location of the parathyroid gland. Birds?
External parathyroid glands: - cranial pole of the thyroid - ABSENT in birds and pigs Internal parathyroid glands: - caudal pole - (embedded within the thyroid tissue)
37
What surrounds the parathyroid gland? What does it blend with?
**thin connective tissue capsule** - blends with the **thyroid connective tissue** | thin connective tissue = stroma
38
What extends from the capsule of the parathyroid gland into the parenchyma? What does it contain?
**Fine septa** extend from the capsule into the parenchyma and contain the **rich endocrine blood supply**.
39
Is it possible to depics two glands in one histological slide?
yes! the thyroid and parathyroid gland!
40
What is the parenchymal part of the parathyroid gland composed of?
**Principal cells = Chief Cells:** - polygonal cells - round nucleus - clear cytoplasm - actively produce *parathyroid hormone (PTH)* (increases blood calcium levels). **Oxyphil cells:** - *inactive* (function is unknown) - larger - more intensive colour (pink) - prominent cell membranes - cytoplasm contains *glycogen* or *lipofuscin*.
41
What is the function of the parathyroid hormone?
Parathyroid Hormone (PTH): - increases **blood calcium levels** - increases *mobilization* of calcium from *bone* - increases calcium *absorption* in the intestines, - reduces calcium *loss* in the urine
42
State the positioning of the two cells of the parathyroid gland.
no specific location! chief cells and oxyphil cells are **mixed** together.
43
What are suprarenal glands? Where are they located? What do they represent?
**Suprarenal Glands = Adrenal Glands** - adjacent to the cranial medial border of the kidneys - represent two distinct endocrine tissues.
44
State the major functions of the suprarenal glands. How is it regulated?
**Outer cortex** secretes *steroid hormones*. **Medulla** produces *catecholamines*. * Hormone production is **regulated independently**.
45
What is the suprarenal gland surrounded with? How does this connect with the parenchyma? What is its function?
surrounded by: ***dense fibrous* connective tissue capsule**. * Connective tissue **trabecula** extend into the parenchyma from the capsule and a **fine stroma** *supports* the *glandular cells*.
46
Why is the name of the gland called "suprarenal" instead of "adrenal"?
**Adrenal**= humans, gland positioned ON-TOP of the kidney **Suprarenal**= (kidneys are horizontal), gland is INFRONT of the kidney
47
What does the 'suprarenal' organ qualify as?
double origin organ: - cortex - inner medulla completely different parts, origin and cells --> produce different hormones
48
What is the function of the suprarenal gland medulla and cortex? (simply)
medulla: similar to the autonomic nervous system cortex: hormone producing glands
49
What are the different zones of the supranatal cortex?
CAPSULE 1) zona glomerulosa 2) zona fasciculata 3) zona reticularis ADRENAL MEDULLA
50
State the arrangement of cells in the suprarenal cortex.
- arranged in *cords* or *glomerular structures* - cells: cuboidal/columnar or polygonal - 3 zones - 4 zones in horses and carnivores
51
State the composition of the zona glomerulosa.
- suprarenal cortex - outermost layer - **outer** zone adjacent to the capsule - cells arranged in **glomeruli** or **curved cords** - small cells! large nucleus! --> cells look darker!
52
What is the special zone of carnivores and horses? Where is it located? What is it composed of?
**Zona Intermedia** - **small** **undifferentiated** cells - present between the zona glomerulosa and zona fasiculata - in **horses** and **carnivores**.
53
State the composition of the zona fasciculata.
- characteristic **foamy cytoplasm** --> large amount of *lipid*. - **widest** zones - larger cells - arranged in columns --> linear pattern arrangement
54
State the composition of the zona reticularis.
- **smaller** cells - **no** specific arrangement --> 3D network - cytoplasm may have **brown** pigment--> darker appearance - adjacent to the *suprarenal medulla* - **innermost** zone of the cortex
55
What hormones are produced in the zona glomerulosa? What produces them?
Zona glomerulosa cells form *ovoid clusters* and produce **mineralocorticoids** (*aldosterone*).
56
What hormones are produced in the zona fasciculata? What produces them?
Zona fasciculata cells are arranged in *long straight cords* and produce **glucocorticoids** (*cortisol*). | stress hormone!
57
What hormones are produced in the zona reticularis? What produces them?
Zona reticularis cells are arranged in *anastomosing cords* produce weak **androgens**.
58
State the composition of the suprarenal medulla. What is it composed of? What cell populations are present in animals? What do they contain?
**Medullary Endocrine** Cells = **Chromaffin** Cells - clear cytoplasm - modified *postganglionic sympathetic* neurons * In animals, **two populations** of endocrine cells are recognized based on the **catecholamines** present in *cytoplasmic membrane-bounded dense granules*. contain one of the catecholamines: - *adrenalin* (epinephrine) - *noradrenalin* (norepinephrine), + *chromogranins* (binding proteins for the catecholamines)
59
What is the function of chromogranins? Where are they found?
- in *cytoplasmic membrane-bounded dense granules*. - binding proteins for the catecholamines
60
What surrounds chromaffin cells? How are they arranged?
- arranged in clumps - surrounded by sinusoidal capillaries
61
How do chromaffin cells look like?
- clear cytoplasm - may appear brown due to the oxidation process
62
What cells are present in the suprarenal gland? How do they look? What are they composed of?
**Epinephrine cells**: - *light* chromaffin stains - *majority* of medullary cells **Norepinephrine cells**: - *dark* chromaffin stains - *minority* of medullary cells
63
State the structure of pancreatic islets. Other name?
**Endocrine pancreatic islets** = **islets of Langerhans**: - *scattered* among exocrine secretory units. - *clusters* of endocrine cells. - connected by *gap junctions* (facilitate intercellular communication)
64
Explain Type A pancreatic islets.
- **dense** cytoplasmic granules. - secretes glucagon, cholecystokinin, gastric inhibitory protein and ACTH-endorphin.
65
State the function of type A pancreatic cell secretions.
* **Glucagon** stimulates *glycogen breakdown* which increases blood glucose levels. * **Cholecystokinin** stimulates *contraction of the gallbladder* and release of pancreatic enzymes. * **Gastric inihibitory protein** *inhibits* the secretion of *gastric acid* and *pepsin* and stimulates the release of insulin in the pancreas.
66
Explain Type B pancreatic islets.
- most **numerous** cell in the islet. - produce **proinsulin**
67
State the function of type B pancreatic cell secretions.
During transport from the Golgi apparatus to the cell surface, the **proinsulin** is converted to **insulin**. - The secretory vesicles fuse with the cell membrane, insulin is released, and the hormone enters nearby capillaries.
68
Explain Type D pancreatic islets.
- **large** - pale cytoplasmic granules. - secrete: **somatostatin** and vasoactive intestinal peptide (**VIP**)
69
State the function of type D pancreatic cell secretions.
- **Somatostatin** *inhibits insulin* and *glucagon* secretion in a local paracrine fashion. - **VIP** *induces glycogen break down* and stimulates gastrointestinal fluid secretion.
70
State the names of other pancreatic islets. What are their functions?
**Pancreatic polypeptide cells** (PP cells or F cells): - increases *glycogenolysis* and regulates *gastrointestinal* activity. **G cells**. - stimulates production of *gastric acid* by parietal cells in the stomach.
71
State the composition of testis. What cells? What is secreted?
**Leydig cells** = **interstitial cells** - found near the *seminiferous tubules* in the testicle. - round/polyhedral - large nucleus. - produce *testosterone*.
72
Is it possible to distinguish between the different pacreatic islet cells?
NO! - but its possible to depict the pancreatic islet themselves
73
State the composition of ovaries. What cells? What is secreted?
- **granulosa** cells - **thecal** cells produce ovarian **hormones**. (Other places where estrogens are produced: liver, pancreas, adrenal glands, skin, brain, adipose tissue etc.)
74
State the composition of the corpus luteum. What cells? What is secreted?
The granulosa cells and thecal cells *enlarge* and transforms to **endocrinous cell populations** of the corpus luteum. Two different types of endocrinous cells: - **Granulated luteocytes** (develop from granulosa cells) - **Thecaluteocytes** (develop from theca cells) Produces hormone **progesterone**
75
State the composition of the adipose tissue. What cells? What is secreted?
Produces **leptin**, **adiponectic** and **resistin** - regulates *energy metabolism*

Histology (22 decks)

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