CVR: Histology Flashcards
Give three examples of plasma proteins.
Albumins, globulins, fibrinogen.
What is the difference between serum and plasma?
Serum is plasma without the clotting factors.
How do you recognise a neutrophil histologically?
Multi-lobed nucleus and granular cytoplasm. Larger than RBCs.
How many types of cytoplasmic granules do neutrophils have and what are they?
3 types.
Primary, secondary, and tertiary granules.
How would you recognise eosinophils histologically?
Bi-lobed, or occasionally tri-lobed nucleus (mickey mouse ears). Distinctive large red cytoplasmic granules. Slightly larger than neutrophils.
How would you identify basophils histologically?
Rare to see.
Bi-lobed nucleus but this is often obscured by many dark stained cytoplasmic granules.
What do basophil granules contain?
Histamine.
How would you identify a lymphocyte histologically?
Large nucleus and clear blue/grey cytoplasm. (can’t differentiate between T and B cells histologically).
How would you identify monocytes histologically?
Distinctive kidney-bean shaped (reniform) nucleus.
Can have some cytoplasmic granules (though officially are classified as agranulocytes).
What three major types of granules are found in platelets and what do they contain?
Alpha-granules: most common, contain proteins for coagulation, inflammation, and wound-healing.
Dense granules: contain small molecules including adenosine, calcium ions. Stimulate platelets at sites of vascular injury.
Lysosomes: contain enzymes.
Where is the haematopoietic bone marrow?
Ends of the long bones and in flat bones e.g. skull, ribs, pelvis, sternum, scapula, vertebra.
In bone marrow, which lies closer to the bony trabeculae, myelon series or erythron series?
Myelon series.
During erythropoiesis, do the cells get bigger or smaller during each progressive step of development?
Smaller!
What is myelopoiesis?
Production/development of white blood cells.
What proportion of the blood is made up of white blood cells?
1% (in the buffy coat)
Which is the predominant leucocyte?
Neutrophils.
40-75% of leucocytes are neutrophils.
20-50% are lymphocytes.
A patient has a Strongyloides stercoralis infestation. This is a parasitic roundworm, Numbers of which cell type increase in patients with worms?
Eosinophil
Where do B-lymphocytes mature in adults?
Bone marrow
How would you identify a plasma cell histologically?
Eccentric nucleus with coarse chromatin - which may look like a clockwork pattern in nucleus, prominent hof (light area next to nucleus - the golgi body).
What is another name for neutrophils?
Polymorphonuclear leucocytes.
When monocytes settle in the liver, what cells do they differentiate into, and what function do they provide?
Kupffer cells.
Monitor blood entering the liver and clear debris, degenerated cells, and potentially harmful materials/bacteria from the gut/bloodstream.
What is the multipotential haematopoeitic stem cell?
Haemocytoblast.
What cell gives rise to platelets?
Megakaryocytes.
Which of these statements concerning erythropoiesis is true?
A: Early precursors are eosinophilic
B: It occurs away from bony trabeculae
C: Nuclear shape becomes increasingly complex
D: Organelle numbers increase
E: The cell gets progressively larger
B: It occurs away from bony trabeculae
Still occurs in the bone marrow, but away from the bony trabeculae.
Eosinophilic = stain pink/purple with H&E, early precursors of RBCs stain blue.
RBCs get progressively smaller as they mature, lose nucleus and organelles.
Respiratory epithelium lines lines the tubular portion of the respiratory tract. Describe this epithelium histologically.
Pseudostratified columnar ciliated epithelium, interspersed by goblet cells.
What sort of epithelium lines the opening of the nose?
Keratinising squamous epithelium.
What does the respiratory epithelium of the nasal cavity rest on?
Richly vascular lamina propria containing seromucinous glands.
Why does the nose contain so many thin walled arterioles?
To warm and humidify inspired air.
How does the olfactory area in the roof of the nasal cavity differ from standard respiratory epithelium?
Olfactory receptor cells with supporting sustentacular and basal cells.
Embedded bipolar neurons with dendritic processes reach the surface of epithelium.
Ducts of serous glands of Bowman.
What is the function of the glands of Bowman in the olfactory centre of the nose?
Produces watery secretion which acts as a solvent of odorous substances.
Irrigate epithelium to refresh it.
What part of the larynx does not have respiratory epithelium?
The vocal cords, which have stratified squamous epithelium, overlying loose irregular fibrous tissue (Reinke’s space).
What sort of cartilage holds open the trachea?
Hyaline cartilage.
What smooth muscle forms the posterior trachea?
Trachealis smooth muscle.
Can you tell the difference between the main, lobar, and segmental bronchi histologically?
No.
How do the bronchioles differ from bronchi histologically?
More sparsely ciliated columnar epithelium, not standard respiratory epithelium.
Both have smooth muscle and some basal neuroendocrine cells.
Bronchioles don’t have cartilaginous rings or seromucinous glands.
Bronchioles have a few goblet cells, and clara cells.
What are clara/club/bronchiolar exocrine cells and where would you find them?
Clara cells are most numerous in terminal bronchioles.
Don’t have cilia. Have many secretory granules.
Function is unknown.
What links the terminal bronchioles and alveolar ducts?
Respiratory bronchioles.
Describe the histological structure of respiratory bronchioles.
Cuboidal ciliated epithelium, spirally-arranged smooth muscle, no cartilage.
Describe the histological structure of alveoli.
Delicate air-filled sacs, surrounded by a network of capillaries sandwiched between the alveoli walls: simple squamous epithelium of type I pneumocytes, with some globular type II pneumocytes.
Which are larger, type I pneumocytes or type II pneumocytes?
Type II pneumocytes.
What do type II pneumocytes do?
Synthesise, store, and release surfactant.
What is surfactant? Why is it important?
Phospholipid based secretion, spreads across alveolus lining.
Reduces surface tension - facilitating expansion and collapse of alveoli during respiration.
Prevents desiccation of alveolus by forming a lipid-like insulating layer over alveolus surface.
Do alveolar macrophages float in the air space inside alveoli?
No, they are adhered to the epithelium, however, often separate during tissue processing so appear to be floating in histological specimens.
In alveoli, how many layers does the air-blood barrier have in simplest possible terms? What are they?
5 layers
1. Surfactant
2. Type 1 pneumocyte
3. Basement membrane
4. Capillary endothelial cell
5. RBC membrane
In alveoli, do type 1 pneumocytes and capillary endothelial cells share a basement membrane or are there two basement membranes between them?
Basement membrane is shared.
Where in the alveoli are the capillary endothelial cells not in direct contact with pneumocytes?
In the alveoli interstitium.
What does the alveoli interstitium contain?
Collagen and elastin fibres, fibroblasts, macrophages.
Describe the visceral pleura histologically.
Flat mesothelial cells resting on a basement membrane, with loose fibrocollagenous connective tissue separating the visceral pleura from the lung tissue.
Which of these is not a feature of respiratory epithelium?
* Basement membrane
* Goblet cells
* Lines the nasopharynx
* Microvilli
* Pseudostratification
Microvilli
Which of these is lined by respiratory epithelium?
* Alveoli
* Bronchi
* Nares
* Roof of nasopharynx
* Vocal cords
Bronchi
What type of tissue holds open the larynx and trachea?
Hyaline cartilage
What tissue bridges the gap between the free ends of C-shaped cartilages in the trachea?
Smooth muscle (trachealis).
Which of the following is present within the walls of bronchi but not bronchioles?
* Arterioles
* Cartilage
* Lymphoid tissue
* Respiratory epithelium
* Smooth muscle
Cartilage
Where is Reinke’s space?
In the vocal cords.
Where are the pores of Kohn?
Alveolar walls.
What are the two main functions of the pores of Kohn?
Provide collateral pathways between alveoli and equalise pressure.
