CTO Quiz #5

Question 1

What are the functions of the endocrine system?

Answer 1

The functions include: regulation of growth, reproduction, metabolism, fluid levels, glandular secretion etc.

Question 2

How does the hypothalamus affect the endocrine system?

Answer 2

The hypothalamus is the site of release of the releasing and inhibiting factors that enter the hypothalamo-hypophyseal portal system and affect anterior pituitary function. It is also the site of neurons that manufacture oxytocin (paraventricular nucleus) and vasopressin (supraoptic nucleus) that send axons through the hypothalmo-hypophyseal tract to end in the posterior pituitary gland. These hormones are released into the blood stream, although they are not made in the posterior pituitary.

Question 3

What is the “master gland of the body”?

Answer 3

The pituitary gland controls many other endocrine glands.

Question 4

What are the functions of oxytocin?

Answer 4

Oxytocin acts on uterine smooth muscle during labor as part of a positive feedback loop. It also contracts myoepithelial cells of mammary alveoli for milk letdown. This may be stimulated by suckling or by psychological factors such as a baby crying.

Question 5

What is the function of antidiuretic hormone?

Answer 5

ADH promotes water resorption from the collecting tubules & vasoconstriction

Question 6

What is the embyologic origin of the adenohypophysis?

Answer 6

The adeohypophysis (anterior pituitary) derives from Rathke’s Pouch

Question 7

What is the capillary organization of the anterior pituitary?

Answer 7

Many capillaries are part of the hypothalamo-hypophyseal portal system that takes releasing factors from the median eminence of the hypothalamus to the anterior pituitary. This system has many fenestrated capillaries and no barrier (such as the blood-brain barrier) in the hypothalamus or the anterior pituitary.

Question 8

What do acidophils of the adenohypophysis secrete?

Answer 8

Acidophils secrete growth hormone (GH; via growth hormone releasing hormone), and prolactin (PRL). These have direct effect on end-organs rather than on other endocrine organs.

Question 9

What does growth hormone do?

Answer 9

Growth Hormone (GH) is produced by somatotropes under the influence of growth hormone releasing hormone (GRH). It increases the synthesis of growth factors, increasing cell division, protein synthesis, and lipolysis. It also helps regulate blood sugar. Low sugar results in increase GRH, which increases GH, which results in glycogen breakdown. High blood sugar results in increased somatostatin release (growth hormone inhibiting factor), which decreases GH and results in less sugar breakdown.

Question 10

What does prolactin do?

Answer 10

Prolactin (PRL) promotes milk production. It is produced by lactotrophs and is normally inhibited by the hypothalamus via dopamine release into the hypothalamo-hypophyseal portal system. Suckling reduces this inhibition.

Question 11

What do basophils of the adenohypophysis do?

Answer 11

Basophils secrete ACTH (corticotropes), TSH (thyrotropes), and FSH, LH (gonadotropes).

Question 12

What do chromophobes of the adenohypophysis do?

Answer 12

Chromophobes are probably not active in secreting hormones. They may be resting or replacement cells.

Question 13

What does the thyroid gland control?

Answer 13

The thyroid gland controls metabolism, heat regulation, growth and nervous development.

Question 14

Describe the histologic appearance of the thyroid.

Answer 14

The thyroid is characterized by large follicles lined by cuboidal follicular cells. There is colloid within the follicles (more in inactive glands) and there are parafollicular “C” cells between the follicles. As with all endocrine glands, there are many capillaries.

Question 15

What is colloid?

Answer 15

Colloid made of the protein thyroglobulin. This is secreted into follicle by the follicular cells. These cells take up iodine and pump it into the follicle where it iodinates thyroglobulin to make T3 and T4.

Question 16

How is thyroid hormone secreted?

Answer 16

Under the influence of TSH, follicular cells reuptake thyroglobulin and liberate T3 & T4. This is secreted into the blood stream.

Question 17

What is the significance of resorption lacunae?

Answer 17

Resorption lacunae are the regions near the active follicular cells where processes of these cells have internalized thyroglobulin, leaving an empty-appearing region adjacent to the cell. These are more prominent in an active thryroid.

Question 18

What do parafollicular (C) cells do?

Answer 18

C cells make calcitonin, which decreases Calcium in blood by several mechanisms, including decreasing intestinal absorption and renal tubular resorption of calcium and by inhibiting osteoclasts in the bone.

Question 19

Why is calcium regulation important?

Answer 19

Hypocalcemia results in muscle cramps and muscle tetany. Hypercalcemia results in muscle weakness and can produce confusion and stupor.

Question 20

Where are the parathyroid glands?

Answer 20

There are usually 4 of them on the back of the thyroid gland. However, the location is variable.

Question 21

What kind of cells are in the parayroid glands?

Answer 21

Chief cells secrete PTH (parathyroid hormone). Oxyphil cells are more eosinophilic, partially due to lots of mitochondria. These cells have no known function.

Question 22

What does parathyroid hormone do?

Answer 22

PTH increases Calcium in the blood. It does this by stimulating osteoclasts to break down bone. It also increases calcium resorption from the GI tract by activating vitamin D and incrases calcium resorption from the renal tubules.

Question 23

What are the layers of the adrenal cortex?

Answer 23

The layers of the adrenal cortex (from superficial to deep) are the zona glomerulosa, the zona fasciculate and the zona reticularis.

Question 24

What does the zona glomerulosa do?

Answer 24

The zona glomerulosa cells secrete mineralocorticoids (aldosterone), which helps regulate electrolyte and water levels. The hormone is under the influence of the renin-angiotensin system.

Question 25

What does the zona fasciculata do?

Answer 25

The zona fasiculata cells secrete glucocorticoids (cortisol). This is a hormone that helps the body deal with stressful situations. It increases blood sugar, fat, amino acids, and blood pressure. It has a circadian rhythm, being high in the morning. This is regulated by ACTH from the adenohypophysis.

Question 26

What does the zona reticularis do?

Answer 26

The zona reticularis secretes androgens. It has little effect in males, but is responsible for testosterone in women and makes estrogen in postmenopausal women.

Question 27

Where does the adrenal medulla arise from?

Answer 27

The adrenal medulla arises from neural crest cells, in a similar manner to sympathetic ganglion cells.

Question 28

What are the cells of the adrenal medulla called and what do they do?

Answer 28

The cells of the adrenal medulla are called chromaffin cells. They are innervated by sympathetics preganglionic neurons and secrete epinephrine and some norepinephrine. These hormones will increase blood pressure, heart rate and blood glucose.

Question 29

What is the endocrine portion of the pancreas called?

Answer 29

The endocrine portion of the pancreas is called the pancreatic islets of Langerhans.

Question 30

What types of cells are in the endocrine pancreas and what do they do?

Answer 30

Beta cells secrete insulin in response to high blood sugar, which is responsible for getting glucose into cells, thereby lowering blood sugar. Alpha cells secrete glucagon in response to low blood sugar. This hormone causes the liver to break down glycogen into glucose and deliver it to the blood. Delta cells secrete somatostatin, which inhibits local hormone production (insulin and glucagon). F cells produce pancreatic polypeptide (which helps regulate other hormone release).

Question 31

What are the cells of the pineal gland called and what are the distinctive histologic features?

Answer 31

The functional cells of the pineal gland are pinealocytes. Corpora arenacea (mineral deposits that show up on CT/MRI) are the most distinctive feature.

Question 32

What does the pineal gland do?

Answer 32

This gland produces melatonin (important in the circadian clock).

Question 33

What kind of epithelium lines most of the oral cavity?

Answer 33

The oral cavity is lined by stratified non-keratinized squamous epithelium

Question 34

What is the histologic structure of the tongue?

Answer 34

It is mostly skeletal muscle lined by stratified squamous nonkeratinized epithelium. There are connective tissue bands and minor salivary glands between bundles of skeletal muscle. The posterior 1/3 of the tongue has lymphoid tissue (lingual tonsil) under the stratified squamous epithelium.

Question 35

What kinds of papillae are on the tongue and what are their structures?

Answer 35

Filiform papillae are the most numerous and appear as short bristles. Fungifom papillae are broader and often have taste buds on their sides. Circumvallate papillae form a row just anterior to the sulcus terminalis and contain a large number of taste buds.

Question 36

What divides the anterior 2/3 of the tongue from the posterior 1/3

Answer 36

The sulcus terminalis.

Question 37

What kind of epithelium lines the pharynx?

Answer 37

The oro- and laryngopharynx are lined by stratified non-keratinized squamous epithelium. The nasopharynx is lined by pseudostratified columnar epithelium with cilia (like most of respiratory tract)

Question 38

What is the innermost lining of the GI tract called, and what are its sub-layers?

Answer 38

The mucosa is the lining of the GI tract. It is comprised of an epithelium, a lamina propria and a muscularis mucosa (smooth muscle).

Question 39

What is the submucosa?

Answer 39

This is the connective tissue layer between the muscularis mucosa and the muscularis externa.

Question 40

What is the structure of the muscularis exterena of the GI tract?

Answer 40

Generally, there is an inner circular and an outer longitudinal layer. The stomach may have an additional layer.

Question 41

What is the outer layer of the GI tract and what is its structure?

Answer 41

There is a layer of connective tissue surrounding the outside of the GI tract. Where there is no mesentery, it is called an adventitia. This layer blends with other connective tissue around the organ. In portions of the GI tract that have a mesentery, there is an added layer of simple squamous mesothelial cells and underlying connective tissue. Where this is present, the outer layer is called a serosa.

Question 42

What kind of epithelium lines most of the GI tract?

Answer 42

Most of the GI tract is lined by simple columnar epithelium.

Question 43

What portions of the GI tract have stratified squamous epithelium?

Answer 43

The oral cavity, most of the pharynx, the esophagus and the anus have stratified squamous epithelium.

Question 44

What portions of the GI tract have submucoasal mucous glands?

Answer 44

The duodenum and the esophagus have submucoasal mucous glands.

Question 45

What is unusual about the muscularis externa of the esophagus?

Answer 45

It consists of skeletal muscle in the proximal third and smooth muscle in distal third (blends in the middle).

Question 46

What portion of the intestines does not have villi?

Answer 46

The colon has no villi.

Question 47

What kind of cell is found in the epithelium of the small and large intestine, but lacking from the stomach?

Answer 47

There are no goblet cells in the stomach.

Question 48

What do most of the surface epithelial cells of the stomach manufacture?

Answer 48

The surface mucous cells produce a sticky mucus with high pH, and lots of bicarbonate

Question 49

What are the infoldings of the stomach mucosa called?

Answer 49

Gastric pits increase the surface area of the stomach to allow surface mucous cells to produce lots of alkaline mucous to protect the lining.

Question 50

What cells of the gastric glands manufacture and secrete hydrochloric acid and what is unusual about their structure? What else do they secrete?

Answer 50

Parietal (oxyntic) cells. These cells have canaliculi to increase surface area. They secrete HCl, using carbonic anhydrase to make acid. The need for pumps to move the hydrogen ions means a high need for ATP and, thus, a lot of mitochondria. These cells also secrete intrinsic factor, needed for the absorption of vitamin B12 from the ileum.

Question 51

What are the cells that make most of the gastric enzymes?

Answer 51

Chief cells produce pepsinogen, which is stored in many zymogen granules.

Question 52

What is the function of enteroendocrine cells in the gastric glands?

Answer 52

Enteroendocrine cells secrete gastrin, which stimulates acid production by parietal cells.

Question 53

Where are the stem cells of the gastric epithelium located?

Answer 53

These are located near the neck of the gastric glands and multiply to replace the lining cells.

Question 54

Outside of parietal cells, chief cells and enteroendocrine cells, what other cells are found in the gastric glands?

Answer 54

Mucous neck cells make a different type of mucus from the surface mucous cells.

Question 55

From large to small, what are the folds of the small intestine that increase surface area?

Answer 55

In the small intestine, plicae circularis are the largest folds. Villi are next largest and microvilli are smallest.

Question 56

What forms the core of an intestinal villus?

Answer 56

The lamina propria forms the core of a villus.

Question 57

Where in the GI tract would you find villi?

Answer 57

Villi are found only in the small intestine.

Question 58

In what layer of the intestine would you find intestinal glands?

Answer 58

Intestinal glands are found in the lamina propria.

Question 59

Where do you find stem cells in the intestines and how long does it take to replace the intestinal lining?

Answer 59

The depths of the intestinal glands contain stem cells (3-6 day complete turnover).

Question 60

Outside of enterocytes and goblet cells, what other cells would you find in the epithelium of the intestinal glands?

Answer 60

Paneth cells secrete lysozyme from granules for bacterial defense.

Question 61

What hormones are produced by cells of the duodenum?

Answer 61

Cholecystokinin (affects the gallbladder) & secretin (affects the pancreas).

Question 62

What are the submucosal glands of the duodenum called?

Answer 62

Brunner's glands produce alkaline mucous (unique structure) in order to help neutralize stomach acid.

Question 63

Which part of the small intestine has the greatest surface area?

Answer 63

The jejunum has the most SA for absorption (long villi and abundant plicae circularis).

Question 64

What is the most obvious difference between the jejunum and the ileum?

Answer 64

The ileum has much more lymphoid tissue, often in Peyer's patches (which are visible to eye).

Question 65

What kind of unique cells are located in the mucosa of the ileum?

Answer 65

M-cells sample antigens and present it to lymph tissue in the region of Peyer's patches.

Question 66

What is uniquely absorbed from the ileum?

Answer 66

The terminal ileum absorbs bile acids & vitamin B12 (requires gastric intrinsic factor).

Question 67

Where does most of the resorption of water and electrolytes take place?

Answer 67

In the small intestines.

Question 68

What is unique about the muscularis externa of the colon?

Answer 68

The longitudinal layer of the muscularis externa (outer layer) has 3 bands.

Question 69

What are the most striking differences between the epithelial layer of the large and small intestine?

Answer 69

The colon has more goblet cells and no villi.

Question 70

What are the prominent bulges in the wall of the large intestine?

Answer 70

These are haustra (large bulges between taenia coli).

Question 71

What is the most striking histologic feature of the appendix?

Answer 71

The appendix has lots of lymphoid tissue with many lymphoid follicles.

Question 72

What is the most striking difference between the rectum and the rest of the colon?

Answer 72

The outer longitudinal smooth muscle layer of the rectum is complete.

Question 73

What happens to the epithelium at the recto-anal junction?

Answer 73

There is a transition from simple columnar epithelium to stratified squamous (keratinized).

Question 74

Where do you find ganglion cells in the GI tract walls?

Answer 74

There is an enteric nervous system which can function autonomously. The ganglion cells (with which parasympathetic preganglionic nerve fibers synapse) are fund in Meissner's plexus (in the submucosa) or Auerbach's plexus (between the layers of the muscularis externa).

Question 75

What kind of glands are the salivary glands.

Answer 75

Salivary glands are compound tubuloalveolar glands. The parotid gland is serous, the submandibular is seromucous and the sublingual glands are mostly mucous glands.

Question 76

What kinds of cells are located between gland cells and basement membrane to aid in movement of secretions out of the acini?

Answer 76

Myoepithelial cells around secretory units help in drainage.

Question 77

What ducts are involved in the progression of product from the acini to the oral cavity of the salivary glands?

Answer 77

Intercalated ducts drain the acini and have a low cuboidal epithelium. Striated ducts have high cuboidal to low columnar epithelium and contain lots of mitochondria and basal infoldings. They are involved in ion transport also secrete lysozyme and transport IgA antibody. These drain into the interlobar ducts, which are between lobules. They are often large (and may have a stratified columnar lining). They are found in connective tissue septae.

Question 78

What is the structure of a pancreatic acinus?

Answer 78

The pancreatic acini make up the bulk of the exocrine portion of the pancreas. They are composed exclusively of serous cells and produce proenzymes that will be activated in the duodenum. They look similar to salivary glend acini except they lack striated ducts and myoepithelial cells and they have centroacinar cells. The fluid part of the secretion is alkaline (bicarbonate rich).

Question 79

What are the functions of the liver?

Answer 79

Hepatic functions include protein synthesis (including transport molecules and clotting factors), bile secretion, detoxification, storage (lipids, glycogen), and gluconeogenesis.

Question 80

What is a portal triad?

Answer 80

The portal triad includes a branch of the portal vein, hepatic artery, and bile duct tributary.

Question 81

What is the lining of the liver sinusoids?

Answer 81

Liver sinusoids have discontinuous capillaries for easy exchange of substanced with the space of Disse.

Question 82

What are Kupffer cells?

Answer 82

These are resident macrophage in the sinusoidal space.

Question 83

What other cells are found in the spaces of Disse?

Answer 83

Ito cells are in the space of Disse. They metabolize vitamin A.

Question 84

Where is the basal aspect of a hepatocyte?

Answer 84

The basal portion of a hepatocyte borders the sinusoid.

Question 85

What is the apical portion of the hepatocyte?

Answer 85

The apical portion of the hepatocyte is the part that forms the wall of the bile canaliculus (there are tight junctions of a junctional complex that separate the apical domain of the hepatocyte from the lateral portion that borders the adjacent hepatocytes).

Question 86

How does bile leave the liver?

Answer 86

The bile cnaliculi drain into the bile ductules that empty into the bile duct tributaries that are in the portal triad.

Question 87

What is the epithelial lining of the bile ducts?

Answer 87

It is simple columnar epithelium.

Question 88

What is the epithelial lining of the gallbladder?

Answer 88

There are simple columnar cells with microvilli.

Question 89

What are the differences between the wall of the small intestine and that of the gallbladder?

Answer 89

The epithelium of the gallbladder has no goblet cells. There is a large lamina propria but no submucosa and the gallbladder lacks a muscularis mucosa. There are mucosal folds but no villi. The muscularis externa is not regularly arranged.

Question 90

What is the function of the gallbladder?

Answer 90

The gallbladder stores and concentrates bile. It removes sodium and chloride from bile (water follows passively). These are pumped from the lateral aspects of the cells, from whence they get into the intercellular space.