Structures and anatomy

Question 1

Simple squamous epithelium

Answer 1

Single layer of flat cells - found in absorptive/filtrative tissues, e.g. blood vessel endothelia, mesothelia lining all body cavities (peritoneum, pericardium, pleura)

Question 2

Simple cuboidal epithelium

Answer 2

Single layer of cube-shaped cells - found in glands and ducts, e.g. thyroid (secreting thyroglobulin-containing colloid), walls of kidney tubules, ducts in breast lobules, cervix

Question 3

Simple columnar epithelium

Answer 3

Single layer of columnar cells, often including Goblet cells - lines the digestive tract

Question 4

Pseudostratified epithelium

Answer 4

One layer of cells, but different shapes and sizes give layered appearance, pseudostratified columnar (cilliated) epithelia found in nasal passage (URT), trachea, bronchi (LRT), inner ear, vas deferens, prostate, epididymis

Question 5

Stratified squamous epithelium

Answer 5

Found (for example) in rectum, vulva, pharynx, and conjuctiva, layers of flat cells

Question 6

Transitional epithelium

Answer 6

Changes shape when stretched (transitional relaxed/distended epithelium) - urethra, bladder, ureter

Question 7

Stratified cuboidal epithelium

Answer 7

Found in sweatgland ducts and male urethra

Question 8

Layers of skin

Answer 8

Epidermis - stratum corneum, lucidum, granulosum, spinosum, basale
Dermis - papillary, reticular
Hypodermis

Question 9

Basal lamina protein network

Answer 9

Composed of type IV collagen, laminin, entactin & perlecan so cells cannot pass through - blood supply to epithelia is via diffusion from capillaries in connective tissue underlying basement membrane (basal lamina + lamina reticularis)

Question 10

Upper GI includes…

Answer 10

Oesophagus, stomach, duodenum

Question 11

Lower GI includes…

Answer 11

Jejunum, Illeum (SI) and colon, AKA the large bowel/LI

Question 12

Large intestine - proximal to distal

Answer 12

Caecum -> Ascending colon -> Transverse colon -> Descending colon -> Sigmoid -> Rectum

Question 13

Layers of digestive system epithelia - outside to inside

Answer 13

Serosa (below diaphragm), or adventitia (above diaphragm) -> Longitudinal muscle -> Circular muscle -> Submucosa -> Muscularis mucosa -> Mucosa

Question 14

Peyer’s patches

Answer 14

A group of well-organized lymphoid follicles located in the lamina propria and submucosa of the distal SI(ileum, jejunum and sometimes duodenum) - almost 50% are in the distal ileum; control gut flora and provide immune defense

Question 15

Brunner’s glands

Answer 15

Secrete alkaline mucus to protect duodenal lining from stomach acid

Question 16

Duodenum - unique features/findings

Answer 16

Leaflike villi, crypts of Lieberkuhn, Brunner’s glands in submucosa

Question 17

Jejunum - unique features/findings

Answer 17

Finger-like villi, well-developed picae circulares, crypts of Lieberkuhn but no glands in submucosa

Question 18

Illeum - unique features/findings

Answer 18

Shorter villi, M cells, Peyer’s patches through lamina propria and submucosa

Question 19

Villus lumen contains…

Answer 19

Capillary villus plexus, and a lacteal (lyphatic vessel for lipid drainage)

Question 20

Oesophagus structure

Answer 20

Outer longitudinal muscle, inner circular muscle, then submucosa (with submucosal glands and plexi), muscularis mucosa, and mucosa - wherein mucosal folds are lined by stratified squamous epithelium; muscle is striated/skeletal at upper (pharyngeal) end, then get progressively more smooth-muscle-based

Question 21

Stomach - two sections

Answer 21

Orad area - Fundus and (proximal) part of body - It and the lower oesophageal sphicter relax during swallowing
Caudad area - Distal body and atria - Controls gastric emptying rate

Question 22

Gastric glands - structure and cell types

Answer 22

2+ long, straight tubular glands (ending at the muscularis mucosae) join and open into one pit through a narrow neck
Pit - Simple columnar epithelium, surface mucous cells (non-Goblet - oval nucleus instead of flat, lots of small mucous droplets)
Mucous neck cells in narrow ‘isthmus’
Parietal cells & chief cells

Question 23

Parietal and chief cells in gastric pits

Answer 23

Parietal cells - In upper body of gastric gland, separated by clusters of chief cells, secrete HCl
Chief cells - In lower gastric gland, basal domain is basophilic, apical domain has secretory granules to secrete pepsinogen

Question 24

Connective tissue - types of fibers and staining

Answer 24

Collagen - thick pink, elastic - purple/black, reticular - fine black

Question 25

Adipose connective tissue location and appearance

Answer 25

Throughout body - Single nucleus around lipid droplet

Question 26

Areolar connective tissue location and appearance

Answer 26

Under epithelia, like in digestive tract/respiratory system - Looks like neurons, loose fibers in all directions, fibroblasts interspersed

Question 27

Reticular connective tissue location and appearance

Answer 27

In lymph nodes, Peyer's patches, bone marrow, kidney, liver, spleen - Needs special stain, thicker black fibers, more meshed as opposed to long straight lines (areolar), circular cells in lymph nodes

Question 28

Dense regular connective tissue location and appearance

Answer 28

Tendons, ligaments, aponeuroses, resp. tract - Large bundles of collagen fibers running in one direction, fibroblasts sandwiched inbetween

Question 29

Dense irregular connective tissue location and appearance

Answer 29

Dermis and liver/spleen capsules - Large bundles of parallel collagen fibers, but bundles run in different directions

Question 30

Elastic connective tissue location and appearance

Answer 30

Mainly arteries - Squiggly zig-zags of elastic fibres

Question 31

Elastic cartilage location and appearance

Answer 31

External ears, eustachian tubes, larynx - Continous line of lacunae arranged next to each other, several layers, dark staining elastic fibres around the lacunae

Question 32

Fibrocartilage location and appearance

Answer 32

Inter-vertebral discs, intra-articular cartilage of knee/wrist/TMJ joints - Fibres in-between but lacunae are separated, arranged in different areas/segments

Question 33

Hyaline cartilage location and appearance

Answer 33

Ribs, nose, larynx, trachea - Small bunches of lacunae dispersed evenly throughout the tissue, light/glassy staining around them with no fibres

Question 34

Alveoli structure

Answer 34

Terminal bronchioles -> Respiratory bronchioles -> Alveolar ducts -> Alveolar sacs Surface epithelium - 40% Type I pneumocytes - Simple squamous epithelium, barrier 60% Type II pneumocytes - Larger, rounder cells with more cytoplasm, secrete surfactant + Supporting tissue + Blood vessels

Question 35

Epithelia in bronchi/bronchioles vs. alveoli, and glands

Answer 35

Walls of bronchi and bronchioles are ciliated cuboidal epithelial cells Seromucinous glands exist under bronchal epithelia Bronchioles have no goblet cells, no SM glands, and no cartilage Alveoli are squamous epithelial

Question 36

Liver - general structure

Answer 36

L/R Hepatic duct, common hepatic duct, gallbladder joins, cystic duct, common bile duct, pancreas, pancreatic duct, duodenum, sphincter of Oddi

Question 37

Hepatic triad

Answer 37

Hepatic triads - Portal vein, hepatic artery, bile duct (+ also a lymphatic vessel but not included in triad)

Question 38

Liver - lobule/sinusoid structure

Answer 38

Lobule - Central vein + Acinus Acinus - Sinusoids lined by hepatocytes, Kupffer cells, hepatic artery branch, hepatic portal vein branch, bile duct, bile canaliculi Sinusoid - Lumen + Kupffer cells, fenestrated endothelial cells, space of disse Space of disse - Stellate and dendritic cells Then hepatocytes lining outside of sinusoid, with bile canaliculi interspersed https://imgur.com/a/o8jZhE6

Question 39

Bile secretion

Answer 39

Produced by hepatocytes, modified by cholangiocytes lining bile ducts, transported into gallbladder for storage CCK -> Gallbladder contraction, pushing bile through common bile duct Sphincter of Oddi also relaxes -> Bile enters duodenal lumen Secretin also participates in bile flow into SI, stimulating biliary and pancreatic ductular cells to secrete bicarbonate and water in response to the presence of acid in the duodenum

Question 40

Bile function

Answer 40

Lipid absorption - Emulsifies fats, breaking down large lipid droplets into smaller ones, because bile salts are amphipathic (hydrophilic and -phobic ends) Waste elimination - Excess cholesterol is converted into bile acids, excreted through biliary system via stool

Question 41

Liver - Lobule vs Acinus

Answer 41

The lobule is a hexagonal structure composed of a central portal, with the ... supplying it at the corners. In contrast, the acini divide the lobule into triangular sections, with the portal vein at the apex and the ... on the base.

Question 42

TDLU basic structure (and IHC)

Answer 42

The TDLU is lined by a double layer of cells; an inner epithelial luminal layer and an outer layer of specialized myoepithelial cells that sit on the basement membrane. This outer basal layer stains brown with CK14 IHC in normal breast, not the inside. The TDLU is surrounded by collagen, adipose tissue, and interspersed connective cells - forming the background stroma. CD44 can also stain rare but vital breast stem cells within this double-walled structure.