Histology of the Endocrine System

Question 1

What are the 3 classes of hormone compounds?

Answer 1

1. Steroid (lipid-soluble)
2. Peptide (water-soluble)
3. Amino acid analogues & derivatives (water-soluble)

Question 2

What class of hormone is secreted by cells of the ovary, testes, & adrenal cortex?

Answer 2

Steroid

Question 3

What class of hormone is secreted by cells of the hypothalamus, pituitary, thyroid, parathyroid, pancreas, GI, & Resp. Tract?

Answer 3

Peptide

Question 4

What class of hormone includes thyroxine, epinephrine, and norepinephrine?

Answer 4

Amino Acid Derivates

Question 5

What gland is found at the base of the brain and is connected to the hypothalamus via a stalk?

Answer 5

Pituitary gland

Question 6

What are the two parts of the pituitary gland?

Answer 6

Anterior
Posterior

Question 7

What are the three subdivisions of the anterior pituitary gland? `

Answer 7

1. Pars distalis
2. Pars intermedia
3. Pars tuberalis

Question 8

What does the posterior pituitary gland consist of?

Answer 8

1. Pars nervosa
2. Infundibular stalk

Question 9

What gives rise to the Ant. Pit.? (Embryo)

Answer 9

Ectoderm

Question 10

What gives rise to the post. pit?

Answer 10

Neuroectoderm

Question 11

What is the pituitary portal system comprised of?

Answer 11

Primary capillary plexus and a secondary capillary plexus

Question 12

Hormone releasing factors (RH) are produced by hypothalamic neurons and then released into the…

Answer 12

Primary capillary plexus

Question 13

From the primary capillary plexus, hormone releasing factors (RH) drain into the….
(This is where they act on endocrine cells in the AP)

Answer 13

Secondary capillary plexus

Question 14

What 3 cell types are described in the Pars distalis?

Answer 14

1. acidophils
2. basophils
3. chromophobes

Question 15

What are acidophils?

Answer 15

Bind acid dyes and stain pink or orange

Question 16

What are basophils

Answer 16

Bind basic dyes and typically stain blue

Question 17

What are Chromophobes?

Answer 17

Pale-staining and may represent degranulated chromophils

Question 18

What do acidophils secrete?

Answer 18

Growth Hormone (somatotropin) & Prolactin
(GPA)

Question 19

What do basophils secrete?

Answer 19

ACTH
TSH
FSH
LH
(B-FLAT)

Question 20

T/F: Thyrotropes are acidophils

Answer 20

FALSE; basophils

Question 21

What do thyrotropes produce?

Answer 21

TSH

Question 22

What are thyrotropes stimulated by?

Answer 22

TRH

Question 23

TSHa acts on the ____________, stimulating production of _______ & ________

Answer 23

Thyroid
T3 & T4

Question 24

T/F: Gonadotropes are basophils

Answer 24

True

Question 25

Gonadotropes provide what hormones in both sexes

Answer 25

LH, FSH

Question 26

What are the target organs of gonadotropes?

Answer 26

Testes & Ovaries

Question 27

What are gonadotropes stimulated by?

Answer 27

GnRH

Question 28

T/F: Corticotropes are acidophils

Answer 28

FALSE; basophils

Question 29

Corticotropes produce POMC which is then cleaved into _________________

Answer 29

ACTH

Question 30

What stimulates corticotropes?

Answer 30

CRH

Question 31

ACTH acts on the ____________ to produce ____________

Answer 31

Adrenal cortex; cortisol

Question 32

T/F: Somatotropes are acidophils

Answer 32

TRUE

Question 33

Somatotropes are the most abundant cells in the POSTERIOR pituitary (T/F)?

Answer 33

FALSE - Ant. Pit.

Question 34

What do somatotropes produce?

Answer 34

Growth Hormone

Question 35

What stimulates somatotropes?

Answer 35

GHRH

Question 36

What does GH stimulate?

Answer 36

Liver & other organs to secrete IGF-1 (which promotes stem cell growth)

Question 37

What does GH target directly (w/ anabolic effects)?

Answer 37

Cartilage & Bone

Question 38

T/F: Lactotropes are acidophils

Answer 38

TRUE

Question 39

What do lactotropes produce?

Answer 39

Prolactin - stimulates milk production in the breast

Question 40

What stimulates and inhibits lactotropes?

Answer 40

Stimulates: TRH Inhibits: Dopamine

Question 41

If a patient has a pituitary adenoma and it affects somatotrophs, lactotrophs, and corticotrophs - what would be seen?

Answer 41

Somatotrophs: Excess GH (acromegaly) Lactotrophs: Excess prolactin, decreased FSH & LH, infertility Corticotrophs: Cushing's disease

Question 42

What do pars intermedia cells secrete?

Answer 42

Melanocyte stimulating hormone (MSH) and endorphins

Question 43

Which MSH regulated production of melanin?

Answer 43

Alpha-MSH

Question 44

Posterior pituitary gland is composed of what two things?

Answer 44

1. unmyelinated axons 2. pituicytes (support cells)

Question 45

What is a herring body? Where are they found?

Answer 45

-Dilations or swellings of the axon, filled with neurosecretory vesicles -Post. Pit. Gland Axons

Question 46

What do herring body swellings contain?

Answer 46

ADH & Oxytocin

Question 47

What is the function of ADH? When is it secreted?

Answer 47

-Increased water reabsorption back into circulation form filtrate in kidney tubules -Released in response to extracellular hypertonicity (dehydration)

Question 48

What is the milk-ejection reflex?

Answer 48

Oxytocin acting on mammary gland, causes milk to be "let down" into lactiferous ducts during lactation

Question 49

What is parturition?

Answer 49

Causes uterine contractions during the second and third stages of labor (oxytocin)

Question 50

What does the pineal gland develop from?

Answer 50

Neuroectoderm

Question 51

What two cell types are in the pineal gland?

Answer 51

1. Interstitial glial cells (like astrocytes) 2. Pinealocytes (modified neurons)

Question 52

What do pinealocytes secrete?

Answer 52

Melatonin

Question 53

When is melatonin secreted?

Answer 53

At night

Question 54

What inhibits melatonin secretion?

Answer 54

Light input from the eye

Question 55

What are the calcified concretions found in the pineal gland?

Answer 55

Brain sand (corpora arenacea)

Question 56

What does the thyroid develop from?

Answer 56

Endoderm

Question 57

What is unique about how the thyroid stores its secretory products?

Answer 57

-Stores it extracellularly in the lumen. It is in cyst-like follicles.

Question 58

A thyroid follicle is formed by a _________________________ enclosing a lumen filled with _______________.

Answer 58

Simple Epithelium Colloid

Question 59

Colloid is a viscous gel that contains mostly

Answer 59

Iodinated thyroglobulin

Question 60

What cells types are found in the thyroid follicle?

Answer 60

1. Follicular cells 2. Parafollicular cells

Question 61

In the lumen of follicular cells what is found (besides tyrosine residues)

Answer 61

T4. T3

Question 62

What are the actions of T3 & T4?

Answer 62

-Regulate metabolism and growth -Increase O2 consumption of almost all tissues -Bind to nuclear receptors (inc/dec gene expression)

Question 63

Colloid levels for hyper- and hypo- thyroidism

Answer 63

HYPO: too much colloid HYPER: too little colloid

Question 64

what do parafollicular cells secrete?

Answer 64

calcitonin

Question 65

What is the function of calcitonin?

Answer 65

Lowers Blood Ca++ by inhibiting bone resorption by osteoclasts

Question 66

What is graves disease?

Answer 66

Autoimmune disease where IgG binds to the TSH receptor on follicular cells, activating the secretion of T4 and T3. Hyperthyroid symptoms.

Question 67

What do parathyroid glands develop from?

Answer 67

3rd and 4th pharyngeal pouches (endoderm) in early embryo

Question 68

What two cell types are found in the parathyroid gland?

Answer 68

1. Chief cells 2. Oxyphil cells

Question 69

What do chief cells secrete?

Answer 69

Parathyroid hormone (PTH)

Question 70

What is the function of PTH?

Answer 70

Increase Blood Ca++ levels

Question 71

How does PTH increase blood Ca++?

Answer 71

-Stimulate osteoblast which then stimulate osteoclast -Osteoclast resorb bone and release Ca++

Question 72

What are oxyphil cells?

Answer 72

-Acidophilic cells -Function not known

Question 73

Adrenal gland cortex and medulla derivatives

Answer 73

Cortex: Mesoderm Medulla: Neural Crest Cells

Question 74

What are the 3 zones in the adrenal cortex (superficial to deep)

Answer 74

1. Zona glomerulosa 2. Zona fasciculata 3. Zona reticularis

Question 75

What 3 hormones are produced by the adrenal cortex (steroid hormones)

Answer 75

- mineralocorticoids (aldosterone) - Glucocorticoids (cortisol) - Androgens (DHEA) 3s (Salt, sugar, sex)

Question 76

The zona glomerulosa secretes what to regulate BP?

Answer 76

Aldosterone

Question 77

What stimulates aldosterone production?

Answer 77

Angiotensin II

Question 78

What does the zona fasciculata secrete?

Answer 78

Hydrocortisone (cortisol)

Question 79

What stimulates glucocorticoid production?

Answer 79

ACTH

Question 80

What does the zona reticularis produce?

Answer 80

Weak androgens, mainly DHEA

Question 81

What stimulates androgen production?

Answer 81

ACTH

Question 82

What do androgens do?

Answer 82

Regulate secondary sex characteristics

Question 83

What is unique about ZF and ZR mitochondria?

Answer 83

They have tubular cristae in mitochondria

Question 84

What two cells types are found in the adrenal medulla?

Answer 84

1. Chromaffin cells 2. Parasympathetic ganglion cells

Question 85

What are chromaffin cells?

Answer 85

Modified postganglionic sympathetic neurons (NO axons or dendrites)

Question 86

What do chromaffin cells secrete?

Answer 86

Epinephrine and norepinephrine

Question 87

What do chromaffin cells synthesize in the adrenal medulla?

Answer 87

Norepinephrine and epinephrine

Question 88

Describe cortical blood supply to the adrenal gland

Answer 88

ZG: - Fenestrated capillaries ZF, ZR: - Sinusoids supply

Question 89

Describe medullary blood supply to the adrenal gland

Answer 89

Comes from two sources: -Venous blood (rich in hormones) reaches the medulla through cortical sinusoids -Arterial blood reaches the medulla via direct branches from capsular artery

Question 90

What does contraction of the central adrenomedullary vein do?

Answer 90

-Rapidly released hormones from the medulla into the blood

Question 91

What is addison's disease (AD)?

Answer 91

-Adrenal insufficiency (destruction of adrenal cortex) - yields cortisol deficiency, hyperpigmentation of the skin and oral mucosa (from increased MSH secretion)