Session 3 Flashcards

Question

features of the bladder

Answer 1

**from lumen inwards** - layer of transitional epithelium (UROTHELIUM) with umbrella cells ★ - lamina propria - muscular layer underneath - adventitia (with fat cells, that act as a shock absorber for the expanding bladder) ★ urothelium - the shapes of the cells differ between relaxed urothelium and stretched (when bladder distended) - the urothelium has umbrella cells (make sure urine, with toxic urea, doesn't escape the bladder) - has intermediate and basal epithelial cells attached to the basement membrane **functions of urothelium** - epithelial cells produce mucus - protects bladder from damage by acidic urine - tight junctions and very well packed, preventing leakage to inner cell layers

Answer 2

- has structure very similar to bladder - except epithelial cells change from transitional → squamous → keratinised squamous (at outlet) - mucus glands produce large amounts of 'sticky' mucus to prevent ingress of pathogens - functionally very similar to GI tract - absorbtion of essential nutrients in the kidney - prevention of pathogen entry (especially in lower urinary tract) - removal of waste products (eg urea)

Answer 3

divided into two parts: 1. conducting portion (nasal cavity to bronchioles) 2. respiratory portion (respiratory bronchioles to alveoli)

Answer 4

**mucosa** - epithelial layer - several cells deep - covered in cilia (moves debris, dust, bacteria etc towards mouth) - lamina propria is very thin - no longitudinal muscularis mucosa layer **submucosa** - connective tissue layer - contains mainly collagen and elastin fibres and many fibroblasts - contains seromucous glands (produce a water mucus that thickens during infection) **C-shaped hyaline cartilage** - can be palpated externally - main function is to keep trachea open - opening is aligned with oesophagus to allow bolus of food to pass - made of two layers: - 1. perichondrium that has fibroblasts that lay down collagen fibres - 2. chondrogenic layer, from which cartilage is formed ## Footnote note: no outer layer of smooth muscle

Answer 5

**mucosa** - epithelial layer - several cells deep - covered in cilia (moves debris, dust, bacteria etc towards mouth) - lamina propria is very thin - no longitudinal muscularis mucosa layer **submucosa** - connective tissue layer - contains mainly collagen and elastin fibres and many fibroblasts - contains seromucous glands (produce a water mucus that thickens during infection) **C-shaped hyaline cartilage** - can be palpated externally - made of two layers: - 1. perichondrium that has fibroblasts that lay down collagen fibres - 2. chondrogenic layer, from which cartilage is formed ## Footnote note: no outer layer of smooth muscle

Answer 6

**secretions form epithelium and submucosal glands of trachea and bronchi contain...** - mucins and water - makes sticky mucus - serum proteins - lubricates the surface - lysozymes - destroys bacteria - anti-proteases - inactivate bacterial enzymes together with a cilia wave, mucus moves materials to the oral cavity where the material can be swallowed **mucocilliary escalator** (more detail on another card)

Answer 7

- found in trachea of lungs - ciliary bodies evident as thin lines (histology) - unusually thick basement membrane - lamina propria rich in immune cells to protect against infection - lamina propria has a layer of elastic fibres - has goblet cells that produce mucus

Answer 8

- histology similar to primary bronchi except... the cartilage is no longer present as a full circle of rings - airway kept open with crescent shaped cartilage - no outer layer of smooth muscle from lumen inwards... - epithelium is pseudostratified and ciliated - bounded by smooth muscle - supported by seromucous glands in the submucosa

Answer 9

**capillaries lined with flattened specialised epithelial cells** - endothelium - attached to fused basal lamina with even thinner epithelial cells on opposite side **folds in basal lamina** - allow for expansion of air sacs when air is drawn into lungs **at the junction, small amounts of collagen** - surrounded by many layers of elastin fibres - role to provide elastic recoil - allows sac to return to empty state on exhalation of gases the connective tissue 'muscle' layers in mucosa are created by collagen and elastin fibres

Answer 10

**sheets of contiguous cells, of varied embyronic origin, that cover the external surface of the body and line internal surfaces, including the body's vessels** embryologic origin: - epithelial tissues are derived from all of the embryological germ layer - *ectoderm* (eg epidermis) - *endoderm* (eg the inner and outer lining of the GI tract) - *mesoderm* (eg the inner linings of body cavities) ## Footnote contiguous = sharing a common border; touching surfaces with epithelial linings include - exterior surface, eg skin - interior spaces opening to exterior (ie GI, resp and genitourinary tract) - interior spaces that don't open to exterior (pericardial, pleural, peritoneum, blood vessels and lymphatic vessels)

Answer 11

**simple (one cell thick)** - squamous - cuboidal - columnar - pseudostratified (specialised + look like they are more than one cell thick) **stratified / compound (more than one cell layer thick)** - squamous - cuboidal - columnar - transitional / urothelium | note: classified based on **top** layer

Answer 12

**primary function is to anchor down the epithelium** * basement membrane = basal lamina + reticular layer * The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits... * Basement membrane is a dense, sheet-like form of extracellular matrix (ECM) that underlie epithelia and endothelia, and surround muscle, fat and Schwann cells * Basement membranes separate tissues and protect them from mechanical stress.

Answer 13

looks flattened and nuclei is pushing plasma membrane up **functions include...** - LUBRICATION (pericardium, pleural membranes, peritoneum/viscera... known collectively as mesothelium). Allows substances to move smoothly - GAS EXCHANGE (type 1 pneumocytes of pulmonary alveoli), fast exchange important - PRODUCT EXCHANGE eg water, nutrients and waste (endothelial cells lining heart and capillaries) - BARRIER (bowman's capsule, skin, oesophagus, conjunctivae of eye, brain)

Answer 14

*a single layer of polygonal cells, whose height and width are approximately equal* - appearance is quite regular - nucleus takes up most of cell **functions include** - ABSORBTION + CONDUIT (exocrine glands) - ABSORBTION + SECRETION (kidney tubules - note here a very thick pink ring around each tubal is the thick basement membrane, preventing fluid accumulation in the surrounding connective tissue layer) - BARRIER / COVERING (ovary) - HORMONE SYNTHESIS, STORAGE + MOBILISATION (thyroid - epithelial cells synthesise thyroglobulin and store in the centre of the follicle ★) ## Footnote ★ centre of the follicle = colloid it's the only organ that stores its product outside of cells reprocess thyroglobulin to produce thyroxine and release that into the blood (hormone)

Answer 15

*a single layer of polygonal cells, whose height and width are approximately equal* - appearance is quite regular - nucleus takes up most of cell **functions include** - ABSORBTION + CONDUIT (exocrine glands) - ABSORBTION + SECRETION (kidney tubules - note here a very thick pink ring around each tubal is the thick basement membrane, preventing fluid accumulation in the surrounding connective tissue layer) - BARRIER / COVERING (ovary) - HORMONE SYNTHESIS, STORAGE + MOBILISATION (thyroid - epithelial cells synthesise thyroglobulin and store in the centre of the follicle ★) ## Footnote ★ centre of the follicle = colloid it's the only organ that stores its product outside of cells reprocess thyroglobulin to produce thyroxine and release that into the blood (hormone)

Answer 16

*a single layer of cells, whose heights are significantly greater than their widths* - eg lines the crypts of Lieberkuhn (intestinal glands) in the mucosa of the colon **main functions:** - ABSORBTION (small intestine, colon and gallbladder) - SECRETION (stomach lining, gastric glands, small intestine and colon) - LUBRICATION (small intestine and colon) **simple columnar with microvilli** - increase the surface area available for absorbtion. Can only be seen as individual entities under electron microscope

Answer 17

**these are tissues in wwhich all cells make contact with the basement membrane, but not all of the cells reach the epithelial cell surface** - this results in nuclei lying at different levels - gives the impression of multiple cell layers - not all cells reach the apical surface - may contain goblet cells - may be ciliated epithelium (eg trachea / mucociliary escalator) - found in lining of nasal cavity, trachea and bronchi **functions include** - SECRETION + CONDUIT (respiratory tract, ductus deferens) - MUCUS SECRETION (respiratory tract) - PARTICLE TRAPPING + REMOVAL (respiratory tract)

Answer 18

- appear clear on H+E histology as they don't bind to sugar easily - goblet cells lack cilia on apical surface, so instead have microvilli - release of mucins through exocytosis - water release increased by release of ions ⚕︎ ## Footnote ⚕︎ deficiency of Cl- release results in very sticky and immovable mucus. Characteristic of Cystic Fibrosis due to mutation in CFTR gene

Answer 19

**mutation in the CFTR gene** → causes deficiency of Cl- → this results in very sticky and immovable mucus in CF, tissues that have mucins and cilia are all affected eg... - airways get clogged and infected with thick and sticky mucus, obstructing breating and damages lungs progressively - liver, where small bile duct gets blocked - pancreas, also involved in digestion - small instestine - thick, non motile stools - reproductive tracts, eg thick mucous plug in cervix - skin where malfunctioning of sweat glands results in very salty sweat and crystals on the surface of the skin

Answer 20

**contain multiple layers of cells, the outermost of which are thin squamous epithelial cells** - top layer is dead and can be easily removed - layers of cells held together by desmosomes - found in all cells close to the external environment **locations include...** - oral cavity - oesophagus - vagina ★ - part of anal canal - surface of cornea - inner surface of eyelid **functions include** - protect against abrasion - reduces water loss but remains moist ## Footnote ★ here, the cells are rich in gylcogen, a substrate for a lactobacilli, which produce lactic acid and therefore maintain a low pH... helps to destroy non native bacteria and viruses ... appears very pink on H+E, with pale centred cells that contains lots of cytoplasm with lots of sugars that can't easily be stained

Answer 21

**contains multiple layers of cells, the outermost of which are squamous cells that have lost their nuclei and cornified (ie become squames of keratin)** - the outermost cells of this epithelium are collectively called the stratum corneum - the epidermis of the skin is the primary site of this type of epithelium - the epidermis contains no blood vessels (it is avascular) - also found inside the lip (oral cavity) **functions include** - protection against abrasion and physical trauma - prevention of water loss - prevention of microbial ingress - shielding against UV light damage

Answer 22

**aka urothelium** - surface cells vary in shape from columnar, cuboidal to flattened - umbrella cells present on top layer, prevents leakage of urine (contains toxic urea) - multiple layers of a variety of cell types - can be relaxed/stretched, depending on the distention of the bladder - location is urinary tract: from renal calyces to ureters, to bladdere to proximal urethra **functions include** - distensibility - protection of underlying tissue from toxic chemicals (very tight junctions between epithelial cells)

Answer 23

- during embryonic development, the heart lungs and gut develop next to a bag-like cavity into which they invaginate - they each become surrounded by serous membrane that has an inner and outer part - like fist going into balloon: fist represents organ, inner balloon wall (visceral serosa) and outer balloon wall (parietal serosa) - serosa surrounds organs, but the organs do not lie within the serous cavity itself - ie pericardial sac, pleural cavity and the peritoneum **visceral** serosal membrane closest to organs in cavity **parietal** serosal membrane lines outer edge of cavity

Answer 24

**mucous** - line vertain interal tubes that open to exterior - eg GI, resp and urinary tracts consists of... - an epithelium lining the lumen of a tube - an adjacent layer of connective tissue (lamina propria) - third layer consisting of smooth muscle cells (muscularis mucosae) - also carries blood, lymphatic vessels and nerves in connective tissue layer) **serous** - thin, two-part membranes which line certain closed body cavities and envelop the viscera - these are spaces that do not open to the exterior - eg peritoneum (abdominal), pleural (lungs) and pericardial (heart) - these serosae exude a lubricating fluid that promotes relatively friction-free movement of the structures they surround consists of... - a simple squamous epithelium (mesothelium) that exudes the watery lubricating fluid - a thin layer of connective tissue that attaches the epithelium to the adjacent tissues - also carries blood, lymphatic vessels and nerves ## Footnote serosae = plural of serous membrane

Answer 25

- **keratin** prevents water loss and protects against abrasion - **cilia** controls micro-movement of luminal contents - **goblet cells** secrete mucus, moistens and lubricates - **microvilli** increases surface area for absorbtion and secretion - **club / clara cells** protect bronchioles and acts as stem cells for respiratory epithelium - **microfold cells** allows rapid sampling of gut microflora - **sterocilia** in the auditory system, which convers pressure waves into electrical signals

Answer 26

on the airway side of the terminal bronchoiles and have club-like apical surface, no cilia and no basal bodies **Functions** - **to protect the bronchiolar epithelium** by secretion of uteroglobin (secretory protein) which is similar in composition to pulmonary surfactant - **detoxification of harmful substances inhaled into the lungs** which is achieved with cytochrome P450 enzymes found in their smooth endoplasmic reticulum act as a stem cell, multiplying and differentiating into ciliated cells to regenerate the bronchiolar epithelium

Answer 27

- found only in the small intestine + very close to lymphatic nodules - M cells have a folded extension that looks like a mushroom cap that samples the lumen by endocytosis - although they are important for the generation of a strong immune response, they are a weak point in intestinal epithelium as many pathogens exploit them as a portal of entry FUNCTIONS - trap pathogens and other molecules - present to underlying dendritic cells that process material - present to lympocytes and macrophages (reside in basal pocket not linked to basement membrane) to raise an immune response or digestions

Answer 28

- in the inner ear, these are the mechanosensing organelles of hair cells - respond to fluid motion for hearing and balance - contain actin and myosin filaments (just like cilia) - longer than normal cilia - in the epididymis and vas deferens, stereocilia facilitate absorbtion of the residual sperm body after spermiation has completed

Answer 29

**early stage** - normal mucus layer thickens - cilia die off - ciliagenesis - 2-4 days **chronic stage** - goblet cells and basal cells proliferate - club cells die - carcinogens induce mutations and malignancy - pneumocytes in the alveoli die ## Footnote proliferate = increase rapidly in number, multiply

Answer 30

**acute bronchitis** - cough and mucus production, breathlessness < 3 months - reduced lung function + breathlessness due to inflammation, swelling and narrowing of the lung airways and excess mucus in the lung passages - increased risk of serious resp diseases later on **chronic bronchitis** - chronic inflammation of the bronchi that produces a cough + mucus production that has at least 2 episodes of cough lasting 3 months or more during a 2 year period - reduced lung function and breathlessness due to inflammation, swelling and narrowing of the lung airways and excess mucus in the lung passages - can cause irreparable damage to bronchioles and alveoli **emphysema** - shortness of breath due to pernament widening of the airspaces distal to the terminal bronchiole without fibrosis (ie destruction of the air sacs) - damage to air sacs, loss of elastic recoil - causes pernament changes to size of alveoli (fuse and enlarge) **COPD** - umbrella condition that includes emphysema and chronic bronchitis **asthma** - wheeze, shortness of breath, chest tightness and could that may vary over time + in intensity, with a variable expiratory airflow limitation - often has a trigger - caused by bronchospasm, obstruction from mucus and narrowing of conducting airways - bronchospasm = tightening of smooth muscle layer in bronchi and bronchioles

Answer 31

**sheets of contiguous cells, of varied embryonic origin, that cover the external surface of the body and line many internal surfaces**

Answer 32

- epithelial cells regenerate rapidly - due to high mitotic rate - allows epithelium to withstand the constant wear and tear it suffers while breaking down food, absorbing nutrients, and eliminating waste - Epithelial tissue contains a large number of stem cells in the lower layers, which constantly divide in order to replace the cells above them - can be renewed in 5-10 days - depends on type of cell (ie how much wear + tear) - renewal process accelerated during wound healing

Answer 33

**parenchymal** cells that occupy most of the tissue volume, express functions that are definitive for the tissue, and interact with all other cell types to facilitate the expression of differentiated function **mesenchymal** cells (such as fibroblasts and smooth muscle cells) are present in all tissues.