Internal surfaces/Histology Flashcards
What structures are within the mucosa?
Epithelium, lamina propria, muscularis mucosa
Which layers are after the mucosa?
submucosa, muscularis externa, adventitia or serosa
What is unique about the muscularis externa of the esophagus? Which cell types line it?
Has a mix of smooth and skeletal muscle as swallowing is both voluntary and involuntary, epithelial is non-keratinished squamous and basal (stem) cells
What surrounds the esophagus?
Adventitia
What type of gland is present in the esophagus’ submucosa?
Mucous secreting gland
Name the 4 regions of the stomach (stomach’s ‘mucosa’)
A. Cardia: mucus production
B. Fundus: Gastric pits, gastric glands secreting gastric juices: HCl, inactive pepsinogen, digestive enzymes and hormones
C: Body
D. Pylorus: mucus production
Which cell type secretes inactive pepsinogen?
Chief cells in the fundus of the stomach
What is unique about the muscularis externa of the stomach?
Inner Circular, outer longitudinal AND oblique layer, when all 3 contract chyme is produced
What surrounds the stomach?
Serosa membrane
What do paneth cells do and where are they?
They are an innate, mucosal defence in the small intestine that release lysozymes and defensins
What surrounds the small intestine?
The mesentery: tissues that attach the intestines to the posterior abdominal wall formed by a double fold of the peritoneum
Which epithelia line the small intestine?
Simple columnar on the villi
Which gland is specific to the duodenum, what is its function and what type of gland is it? What surrounds the duodenum?
Brunner’s glands (branched tubular) in the submucosa secrete alkaline mucus to counteract the acidic chyme: this protects the mucous membrane and creates optimal pH for enzymatic digestion
Surrounded by adventitia
What is unique about the muscularis externa of the jejunum? Label it on the diagram
What surrounds the jejunum?
Has an Auerbach’s plexus dividing the inner circular and outer longitudinal layer of the muscularis externa, it is B
Surrounded by serosa
What differentiates the inner circular layer from the outer longitudinal layer of muscularis externa? How might you differentiate them on histology?
The outer longitudinal layer has more defined nuclei, and relaxes slower
Name the 3 layers to the serosa?
Parietal (outer) layer: produces surfactant secretions
Serous cavity: contains the lubricating fluid, allows friction free movement
Visceral (inner) layer: produces surfactant secretions
What structure is unique to the ileum? What are they and what do they do?
Peyer’s patches in the lamina propria, they are aggregates of lymphoid follicles for immune surveillance and can release immunoglobulins and protect against pathogens
What structures are unique to the colon? What differentiates the colon from the small intestines?
Has a thinner mucosa, submucosa and muscularis externa with no plicae circularis:
Crypts of lieberkun amongst the epithelial: which has cells involved in host defence and signalling, stem cells and goblet cells
The longitudinal layer of muscularis externa has 3 distinct bands called taenia coli
What aspects of the digestive tract aid its role in absorption?
Plicae circularis, villi, microvilli, and the SI is 4-6 m long
What makes the conducting and respiratory portion of the resp tract?
Conducting: nasal cavity/mouth -> bronchioles
Resp: Terminal bronchioles -> alveoli
Which epithelia lines the upper resp tract?
Pseudostratified ciliated columnar
Which epithelia are in the nasal cavity? What gland is within the lamina propria?
Olfactory and respiratory epithelia:
Olfactory make up the superior part of the nasal cavity, they have olfactory chemoreceptors that can sense smell and have olfactory nerves.
Respiratory epithelia line the rest of the nasal cavity; they are thinner, have mucus-secreting glands, abundant goblet cells and no nerves
Bowman’s glands are within the nose which produce fluid to dissolve odiferous substances
Name the layers of the trachea and how they interact with the esophagus
- Pseudostratified epithelia
- Lamina propria
- Submucosa: has seromucus glands (tubuloacinar)
- C shaped cartilage
- fibroelastic membrane
- Trachealis muscle: relaxes on swallowing and contracts when you cough, it joins hyaline cartilage to the esophagus
What changes as you move down the bronchus-bronchioles?
Epithelia changes from pseudostratified columnar to some simple cuboidal which helps gas exchange
The muscularis mucosa (smooth muscle) and cartilage eventually disappears as you move down the bronchioles
What are the 3 types of cells in the alveoli?
Type 1: simple squamous for gas diffusion
Type 2: simple cuboidal secrete surfactant
Type 3: alveolar macrophages
Where are the transitional epithelia? What is their role?
Line the urinary tract from the renal calyces to the proximal urethra, they provide a distensible barrier against the underlying cytotoxic effects of urine
Name the layers of the ureter
- Transitional epithelia
- Thick fibroelastic lamina propria
- muscularis externa: peristaltic waves to propel urine to the bladder
- Adventitia
Describe the layers of the bladder
- Epithelium: transitional and umbrella cells, basal cells are visible when the bladder is relaxed
- Lamina propria
- Submucosa
- Muscularis: 3 layers forming the detrusor muscle
- Upper is covered in serosa and the rest by adventitia
What lines the female and male urethra?
What glands are present in the distal region, and what type of gland are they?
Proximally transitional cells for both sexes
Distally: sebaceous glands (branched acinar)
Male: Stratified columnar
Female: stratified squamous non-keratinised
What method of secretion do the salivary glands use?
Exocrine
What type of gland is the parotid? How would it appear on histology? What epithelia aids their secretions?
Branched acinar, columnar epithelia aid their serous secretions, they stain the darkest (serous)
What type of gland is the submandibular? What aids their secretions?
Tubuloacinar, secretes serous and mucus so has mixed light and dark portions, striations on the ducts reabsorb Na+ to help draw water out of cells and hydrate the saliva, lined with simple columnar and myoepithelial cells
What type of gland is the sublingual gland? What does it secrete and what epithelia surrounds it?
Tubuloacinar, secretes mucus to stains lighter, surrounded by stratified squamous non-keratinised
What type of glands are the liver and pancreas?
Mixed: endocrine and exocrine portions
What are the exocrine and endocrine functions of the liver?
Exocrine: produces bile through the lobules (functional unit): aided by simple cuboidal and simple columnar epithelia
Endocrine: Produces plasma proteins; albumin, fibrinogen, transferrin, apolipoproteins
What is the role of hepatocytes?
Protein synthesis, detoxification and storage (TAGs, glycogen, iron), production of bile
What makes up the portal triad?
Bile duct (simple cuboidal epithelia), portal vein (large and irregular), hepatic artery (smaller with endothelium)
What are the exocrine and endocrine functions of the pancreas? What epithelia aid secretions?
Exocrine: serous acini drain into a branched duct system (ductal epithelia are cuboidal and columnar) and produce bicarbonate containing fluid for the transport of the hydrolytic enzymes
Endocrine: Islet of Langerhans (round, pale and oval) releases insulin and glucagon
What method of secretion is used by glands in the skin?
Exocrine
What type of gland is a sebaceous gland and where are they? What type of secretion do they produce and what method of excretion do they use? What stimulates their secretions?
Simple branched acinar, located all over in the body except in smooth regions and use holocrine secretion: sebatocytes secrete sebum, which is stimulated by sex hormones around puberty
What stimulates sweat glands and what type of gland are they? What method of excretion od do they use?
Simple coiled tubular, stimulated by sympathetic. Merocrine secretion and apocrine in hair areas
