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NeuroEndo Exam 3 > Histology of Endocrine Organs (Brauer) > Flashcards

Histology of Endocrine Organs (Brauer) Flashcards

1
Q

What is difference between the endocrine and nervous system?

A
  • Nervous:
    • Rapid communication
    • Short lived effects
  • Endocrine:
    • Slower communication via release of hormones into blood and binding on receptor cells
    • Longer lasting effects
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2
Q

What are the stimuli that control hormonal release?

A
  • Humoral
  • Neuronal
  • Hormonal
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3
Q

What is humoral stimuli?

A

Release of hormones are controlled by levels of ions and nutrients in blood/body fluids

Ex: PTH stimulated by low Ca2+ levels

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4
Q

What is neuronal stimuli?

A

Release of hormones stimulated by nerve signals

Ex: Epinephrine is relased from adrenal gland signaling via sympathetic nerve fibers

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5
Q

What is hormonal stimuli?

A

Hormones secreted into the blood by another endocrine tissue

Ex: TSH from pituitary gland stimulates TH release in the thyroid

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6
Q

How are endocrine glands organized?

A

Epithelioid cells arranged as follicles which lack free surfaces (does not open to lumen). They are well vascularized with fenestrated endothelium.

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7
Q

What are the direct targets of hypothalamic hormones?

A
  • Anterior pituitary gland (releasing and inhibiting factors)
  • Kindey and uterus (ADH & Oxytocin stored in posterior pituitary)
  • Adrenal medulla (sympathetic innervation)
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8
Q

What are the indirect targets of hypothalamic hormones and how are the stimulated?

A

Indirectly influenced by stimulating secretion of hormones by the anterior pituitary

TSH –> ​Thyroid gland

ACTH –> Adrenal cortex

Prolactin –> Mammary gland

FSH/LH –> Gonads

GH & MSH –> Bone & other organs

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9
Q

What are the embryoligcal origins of the anterior and posterior pituitary gland?

A
  • Anterior Pituitary: Surface Ectoderm
    • From Rathke’s Pouch
  • Posterior Pituitary: Neuroectoderm
    • From diencephalon
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10
Q

What kind of cell types compose most of the anterior pituitary gland?

A

Glandular epithelial cells controlled by neurohormones released from hypothalamus

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11
Q

What composes most of the posterior pituitary gland?

A

Axons from hypothalamus and support cells

Looks like nerve tissue

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12
Q

Identify the various components of the pituitary gland

A
  • Pars Distalis
  • Pars Nervosa
  • Pars Tuberalis
  • Pars Intermedia
  • Cyst Intemedia: remnant of lumen of Rathke’s pouch
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13
Q

What are some major cell types in the Pars Distalis (Anterior pituitary)?

Are they acidophilic or basophilic?

A

Acidophilic:

  • Somatotropic cells
  • Mammotropic cells

Basophilic:

  • Thyrotropic cells
  • Corticotropic cells
  • Gonadotropic cells

Chromophobes - unknown function

Sinusoidal (fenestrated) capillaries

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14
Q

What do somatotroph cells release?

How do they stain?

A
  • Secrete Growth Hormone (GH) in response to GHRH
  • Acidophilic (lighter)
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15
Q

What do mammotroph cells release?

How do they stain?

A
  • Secrete prolactin to stimulate milk production
  • Acidophilic (stain lighter)
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16
Q

What do corticotroph cells release?

How do they stain?

A
  • Secrete ACTH: stimulates adrenal cortex to secrete stress related hormones and mediate metabolism
  • Basophilic (stains lighter)
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17
Q

What do thyrotroph cells release?

How do they stain?

A
  • Secrete TSH
  • Basophilic (stain darker)
18
Q

What do gonadotropic cells release?

How do they stain?

A
  • Secrete FSH and LH
  • Basophilic (stain darker)
19
Q

What is the Pars Nervosa

A

Posterior part of the Pituitary gland. Continues with the median emince of the hypothalmus via the infundibular stalk. It does not manufacture hormones, rather it stores and releases them from axon terminals

20
Q

What does the pars nervosa consist of?

A
  • Unmyelinated axons from hypothalamus
  • Herring bodies: axonal nerve terminals that store ADH and oxytocin
  • Pituicytes: glia like
  • Fenestrated capillaries
21
Q

How does blood supply to the hypothalamo-hypophyseal portal system work?

A
  1. Primary Capillary Plexus: Hormones released from hypothalamus to anterior pituitary
  2. Hormones travel through portal veins in anterior pituitary
  3. Secondary Capillary Plexus: hormones from anterior pituitary gland enter general circulation to reach targers
22
Q

How does the hypothalmo-hypophyseal tract work in the posterior pituitary gland?

A
  1. Hypothalamus synthesize ADH and oxytocin
  2. ADH and oxytocin are transported to posterior pituitary for storage
  3. ADH and oxytocin are released via hypothalamic signals
23
Q

Where is the pineal gland located?

What does it consist of?

A

Outpocketing of diencephalon’s roof of the third ventricle

Consists of

  • Pinealocytes: secretes melatonin
  • Neuroglia
  • Calcified granular material
24
Q

What is the function of the pineal gland?

A
  • Regulates growth, development, and circadian rhythms
  • Snythesizes serotonin and melatonin
25
Q

What are the histological characteristics of the thyroid gland?

What is unique about the thyroid?

A
  • Contains follicles with a layer of follicular cells (simple cuboidal/simple columnar) surrounding colloid fluid
    • Colloid contains thyroglobulin (storage form of T3 and T4)
  • Only gland to store hormones outside of the cell
26
Q

How are thyroid hormones synthesized and releasd?

A
  1. Thyroglobulin are synthesized in rER, glycosylated in Golgi and stored in lumen (colloid fluid)
  2. Thyroglobulin is iodinated at the apical surface forming T3 and T4
  3. TSH stimulates internalization of thyroglobilun via endocytosis, freeing T3 and T4 and releasing them from basal surface into the blood
27
Q

Parafollicular C Cell

Where is it located?

What is its function?

A

Located near follicles in thyroid gland (periphary).

Function is to secrete calcitonin when blood levels of calcium are high

Calcitionin tones down calcium

28
Q

How does calcitonin lower circultaing calcium levels

A
  1. Stimulates excretion of Ca2+ by kidneys
  2. Decreases Ca2+ releasing activity of osteoclasts
  3. Increases osteogenesis by osteoblasts
29
Q

What is Grave’s Disease and its sypmtoms?

How does it occur?

A
  • Abnormal antibodies stimulate TSH receptors, increasing secretion of T3 and T4 from thyroid
  • Symptoms:
    • Elevated metabolism
    • Sweating
    • Rapid HR
    • Weight Loss
    • Eyeballs may protrude
  • More common in women
30
Q

How does ​hypothyroidism occur?

What is its symptoms?

A
  • Insufficient T3 and T4 production most likely due to an autoimmune disease
  • Symptoms:
    • Low metabolic rate
    • Weight gain
    • Lethargy
    • Chilliness
    • Edema
    • Mental sluggishness
31
Q

What can cause a goiter?

A
  • Thyroid enlargement due to iodine deficiency
  • Follicular cells keep making thyroglobulin but cannot iodinize it to make T3 or T4
32
Q

Parathyroid Glands

Where are they located?

What cell types are present?

What hormones do they release?

A
  • Found on posterior surface of thyroid
  • Function: Release hormones to regulate calcium and phosphate levels
    • Chief cells: Release Parathyroid hormones (PTH) when blood conc. of calcium falls below normal range.
    • Oxyphil cells: function unknown
33
Q

How does PTH regulate calcium levels?

A
  • If calcium levels low (<9.5 mg/dL), parathyroid releases PTH into bloodstream
    • Stimulates osteoclasts to resorb bone and release Ca2+ stores
    • Increase calcium retention by the kidneys
    • Stimulates kidney to convert inactive form of Vitamin D to Calcitriol
    • Calcitriol increases Ca2+ absorption by intestines
  • As calcium levels increase, PTH is inhibited
34
Q

What are the three layers of the adrenal cortex and what are their functions?

A
  • Zona Glomerulosa (mineralcorticoids): Influence Na+ and K+ levels
    • Aldosterone: secreted in response to low BP/BV
  • Zona Fasciculata (glucocorticoids): Influences glucose metabolism and immune system. Controlled by ACTH
    • Cortisol: secreted to deal with stress and mediate glucose. Also negative feedback to immune system
  • Zona Reticularis: Influence secondary sex characteristics
    • Androgens released
35
Q

Label the following components of the adrenal gland.

What hormones are secreted by 1-4?

A
  1. Zona glomerulosa: aldosterone
  2. Zona fasciculata: Cortisol
  3. Zona Reticularis: Androgens
  4. Medulla: NE and EPI
  5. Cortex
  6. Medulla
36
Q

What is the Adrenal Medulla

A
  • Inner core of adrenal gland that consists of chromaffin cells
  • Stiumlated by presynaptic sympathetic to secrete epinephrine and norepinephrine to prepare body for an emergency or flight or fight situation
37
Q

Addison’s Disease

What causes it?

What are its symptoms?

A
  • Hyposecretion of glucocorticoids and mineralcorticoids
    • Blood glucose and sodium levels drop
  • Causes: autoimmune disease or inherited metabolic disease leading to enzyme deficiencies
  • Symptoms
    • Hypotension
    • severe dehyration
    • Fatigue
    • Loss of appetite
38
Q

Cushing’s Syndrome

What causes it?

What are its symptoms?

A
  • Hypersecretion of glucocorticoids
  • Causes:
    • ACTH secreting tumor in pituitary gland
    • Tumor in adrenal cortex
  • Symptoms:
    • High serum glucose levels
    • Protein loss in muscle
    • Muscle weakness
    • Lethargy
    • Swollen Face
    • Fat redistribution
    • Depression of immune responses
39
Q

How is the pancrease organized?

A

Exocrine Portion: majority of pancreas

  • Aids in digestion
  • Organized as pancreatic acini

Endocrine Portion:

  • Organized as pancreatic islets or islets of Langerhans
  • Scattered among exocrine cells
40
Q

What cells are found in the endocrine pancreas?

A
  • Alpha cells: secrete glucagon when glucose levels are low
    • Releases glucose from liver glycogen stores
  • Beta cells: insulin when glucose levels are high
    • Promotes glycogen storage and entry of glucose into cells
  • Delta cells: somatostatin to slow the release of insulin and glucagon
    • Stimulated by high levels of nutrients in the blood
  • F cells: pancreatic polypeptide that inhibits release of somatostatin
41
Q

Explain the pancreatic blood supply

A

Dual blood supply by Acinar vascular system and Insuloacinar portal system

NeuroEndo Exam 3 (16 decks)

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