Histo Respiratory System

Front 1

1. Function of respiratory system
2. Structural divisions

Back 1

1.
- Gas exchange (O2/CO2 exchange, pH regulation, excretion)
- Phonation
- Olfaction

2.
- Airway: moves air in and out of terminal structures (associated wtih phonation and olfaction)
- respiratory portion: gas exchange.

Front 2

Airway characteristics

Back 2

1. epithelial lining
- barrier function
- ciliated and secretory (goblet) cells
2. Lamina propria: immune cells location
3. submucosa: glands, nerves, blood vessels
4. smooth muscle: regulate airway diameter.

Front 3

Epithelial cells in major airway structures.

Back 3

Trachea & Bronchi
ciliated, goblet, granule (enteroendocrine), brush (sensory).

Bronchioles:
ciliated, goblet, granule, clara.

- brush: general sensory receptor
- granule: release hormones/peptides, local control of macrophage and mucociliary functions through cholinergic signaling mechanism.

- clara cell: secrete surfactant like material to keep bronchioles open and clara cell protein CC16 (diagnostic marker for lung injury).

- basal cell: reserve population for replacing epithelium.

Front 4

Function of mucus:

Back 4

- protects and moistens airway
- traps inhaled particles and pathogens: contains anti-inflammatory and anti-bacterial compounds and mucin proteins (increase viscosity)

Front 5

regulation of normal mucus secretion

Back 5

CN vagus nerve (circadian)
to cholinergic receptors (ACh) and substance P and neurokinin A.

Front 6

Inflammation alter mucus production (chronic condition)

Back 6

1. Inflammation (infection,allergy etc) triggers T cells
2. T cells trigger interleukin:

(a) IL stimulated hyperplasia of mucus secretion cells

(b) IL stimulated ciliated dysfunction:

(c) IL stimulated mucin synthesis, excess mucus synthesis.

Front 7

1. Primary ciliary dyskinesia
2. Cystic fibrosis
3. Asthma (COPD)

Back 7

1. dynein arms are congenitally absent, ciliary beat is compromised and mucus stasis occurs -> more mucus secretion (vicious cycle)

2. altered chlorine channel fucntion lead to increase mucus viscosity, impaired mucus clearnace and mucus stasis (Cl- channel not moving Cl- into mucus so H2O doesn't follow Cl- into mucus -> mucus dehydration)

3. mucus accumulation as result of chornic inflammation and bronchiole diameter decrease through sm mm contraction.

Front 8

Regulators of Asthma

Back 8

1. mast cells (secrete heparin & histamine)
- vasodilation and edema which maintain chronic inflamation
- stimulate eosinophils --> stimulate smooth muscle hypertorphy
- stimulate central nervous system to trigger increase mucus production
2. eosinophils: muscles hypertrophy, secretion of Major Basic Protein associated with epithelial cell damage.

Front 9

Alveolar wall change in asthma.

Back 9

- thickening of smooth muscle layer via mast cell and eosinophil stimulation
- increase constriction of airway
- vasodilation and edema to mobilize more oesinophil etc
- sensor in epithelial cell stimulate CNS to secrete more mucus production.

Normally, constriction is beneficial, but when sm mm wall is thickened, constriction reduce airway too much.

Front 10

Emphysema

Back 10

Loss of gas exchange, not due to airway blockage as in asthma.
1. Inflammatory response leads to macrophage and leukocyte (neutrophil) recruitment (excess)
2. Neutrophil secrete protease and elatase -> alverolar wall break down and alveolar wall and elastic fibers (lose elasticity and recoil)
3. large alveolar space due to break down of alveolar septa -> surface area for gas exchange decreases.

Front 11

Gas exchange structures

Back 11

1. respiratory bronchioles
2. alveolar ducts
3. alveoli
- form barrier between air and blood (gas exchange between air and blood)
- 2 types of pneumocytes
4. capillaries in alveoli
- lined by endothelial cells, thin CT (collagen & elastic fibers) interstitial layer b/t basal layers.

Front 12

Alveolar wall cell types

Back 12

1. Type I pneumocytes (8%)
- small fraction of population but occupy surface b/c extremely thin and large
- interface for gas exchange
- energy-dependent membrane associated pumps to removed exudates/fluid block exchange.

2. Type II penumocytes (16%)
-twice abundant tha type I but occupy 5% surface are
- round
- contain lamellar bodies secrete surfactant, a choline-derived phospholipid that reduce surface tension and prevent collapse of alveolar spaces
- precursor population that differentiates and replace type I cells

3. Alveolar macrophages aka dust cells (10%) - scavenge particular matter, virus, bacterial
- migrate upwards bronchial system then swept out in mucous layer
- or leave alveoli into intersistial sapce form black deposits in septae and pleural surface

4. Capillary endothelial cells: (30%) flattened nuclei

Front 13

Characteristics of trachea, bronchi and bronchioles

Back 13

trachea:

bronchi
- smooth mm with cartilage interspecsed, glands, sm and sk mm.

bronchioles:
- continuous sm mm with no cartilage, no glands, simple columnar epithelium

Front 14

respiratory system
Airway Lab

Back 14

Nasal septum: has goblet cells
Olfactory Epithelium
- no goblet
- (lumen-> base) sustentacular, olfactory cells (bipolar neuron), basal cell in ciliated pseudostratified columnar.
- Bowman's glands in lamina propria.
- large veins

Epiglottis:
- elastic cartilage; oral side stratified squamous epi (parakeratinized); respiratory side pseudo ciliated with goblet cells. Exocrine glands in lamina propria

respiratory epithlium:
1. goblet cells in thinner mucosa
2. no glands or nerve in submucosa

larynx
- large hyaline cartilage; collagen in fibrous lamina propria; submucosa merge with periochondrium of hyaline cartilage.

Trachea: smooth muscle connect perichrondium of noncontinuous hyaline cartilage.

Front 15

Lung Lab

Back 15

Bronchus - only structure with hyaline cartilage in lung

Bronchioles:
- sm muscle
- ciliated cuboidal/pseuostratified epithelium line lumen
- next to pulmonary artery b/c artery tree follow bronchiole tree (no vein)
- respiratory: open directly into aveoli, non-continuous smooth mm
no cartilage

Respiratory Bronchiole:
small bits of smooth muscle and thicker epithelium than in alveoli

Alveoli
- arranged in row
- capillaries in septa
- macrophages: round floating cells
- type II: pale round embedded in epithelium

Lung wtih carbon particles
- black dots
- fibrosis: excess type I collagen fiber (inflam. resp. by TGF) -> alveolar space is smaller

Fetal lung
- large white space: futere bcronchiole, alveoli closed, look like glands.