Histology Flashcards
Identify the cartilaginous and muscular structures of the trachea and outline their function
- C-shaped rings of hyaline cartilage, to support the mucosa
- Trachealis joins the free ends posteriorly, to reduce tracheal diameter and increase intrathroacic pressure
Outline the five components of the respiratory epithelia of the trachea
- Pseudostratified Ciliated Columnar Epithelia
- Goblet Cells
- Serous Glands
- Basal Cells
- Stem Cells
Are the ciliated columnar cells, goblet and basal cells more plentiful in the upper or lower trachea?
- Ciliated epithelia more plentiful in lower trachea
- Goblet and basal cells more common in upper trachea
Aside from the respiratory epithelia, outline the other histological layers of the trachea
- Lamina Propria
- Smooth Muscle
- Submucosa
- Perichondrium
Identify four histological differences between the trachea and primary bronchi?
- Epithelia is less tall
- Lamina propria contains more elastin
- Submucosa contains fewer serous glands
- Cartilage is flattened and composed of intercalated discs
Identify six histological components of the tertiary bronchi
- Tall columnar epithelium
- Lamina Propria, containing elastin
- Smooth muscle, for expiratory contraction
- Submucosa, containing sparse serous glands
- Cartilage is flattened and composed of irregular plates
- Adventitia containing lymphocytes (MALT)
Do the bronchioles contain cartilage and / or submucosal glands?
- They contain neither cartilage nor submucosal glands
Which type of epithelia do bronchioles possess?
- Ciliated columnar epithelium
What is the function of the smooth muscle contained within the bronchioles?
- Controls resistance to airflow within the lungs
Which vessel lies next to the bronchiole?
- Pulmonary artery
Identify the two types of bronchioles
- Terminal bronchi are proximal and conductive
- Respiratory bronchi are distal and involved in gaseous exchange
Identify the additional cell type present in bronchioles that is not present and identify three functions of this cell
- Clara Cell:
- Produces surfactant components
- Stem cells
- Contain enzyme system that detoxify noxious substances
Identify the structures distal to the respiratory bronchioles
- Alveolar Ducts
- Alveolar Sacs
- Alveoli
What are alveolar rings?
- Found within walls of alveolar ducts
- Contain smooth muscle, collagen and elastic fibres
What name is given to the small opening in the alveoli that allow movement of air between adjacent alveoli and where are they located?
- Alveolar Pores of Kohn
- Alveolar Septa
Identify the two types of Pneumocytes and their function
- Type 1: Squamous cells that line the alveoli
- Type 2: Secrete surfactant
What is the respiratory membrane composed of?
- Type 1 pneumocytes
- Fused basement membrane
- Cytoplasm of capillary endothelial cell
Identify the structure of a cardiac muscle fibre
- Long cylindrical cell
- Striated
- Two centrally located nuclei
What are intercalated discs and identify two functions
- Intracellular junctions
- Provide points of anchorage
- Permit rapid spread of contractile stimuli from one cell to another
Outline the three layers of the vessels of the circulatory system
- Tunica Intima composed of endothelial cells
- Tunica Media composed of smooth muscle
- Tunica Adventitia
Outline the histological features of the elastic arteries, with reference to their three layers
- Tunica Intima is flat
- Tunica Media is broad and elastic
- Tunica Adventitia contains small vasa vasorum
- Also present are fibroblasts and myointimal cells
Why are myointimal cells not considered epithelia?
- They are not invested by basement membrane
What is the clinical significance of myointimal cells?
- Accumulate lipid with age
- Results in atherosclerosis
Outline the histological features of the muscular arteries, with reference to their three layers
- Tunica Intima is thin
- Tunica Media is broad and composed of muscle with scanty elastic fibres
- Tunica Adventitia is composed of collagen
Describe the two layers of lamina in muscular arteries and where they are located
- Internal elastic lamina between tunica interna and tunica media
- External elastic lamina between tunica median and tunica adventitia
Which layer of the elastic lamina is usually absent in smaller muscular arteries?
- External elastic lamina
What two changes occur in the transition between arteries and arterioles?
- Loss of the internal elastic lamina
- Reducing in number of muscle layers in the media
What is the function of the microcirculation?
- Exchange of gases, fluids, nutrients and metabolic waste products
What name is given to the cells where this exchange process takes place?
- Capillaries
- Which form an interconnected network
What controls blood flow within the capillaries?
- Precapillary sphincters
What are metarterioles?
- Capillaries with a larger diameter
- Characterised by a discontinuous outer layer of smooth muscle
Describe the histological structure of the capillaries with reference to endothelium, nuclei and additional cells
- Single layer of flattened endothelial cells
- Flattened nuclei
- Pericytes which have a contractile function
Identify the force compelling venous blood to the heart
- Smooth muscle
- External compression of skeletal muscle
How is back-flow of blood prevented in veins?
Failure of this process results in what condition?
- Valves which are derived from the intima
- Varicose veins
Identify the 3 types of venules and how they differ from one another structurally
- Postcapillary which are smallest
- Confluence which are larger with more pericytes
- Muscular Venules which acquire a layer of smooth muscle
How do the walls and lumens differ in arteries and veins?
- Walls are thinner in veins
- Lumens are larger in veins
What is meant by the term vena comitantes?
- Multiple veins
- Closely associated with arteries in peripheral regions
Outline the histological features of the small and medium sized veins, with reference to their three layers
- Tunica Intima is thin
- Tunica media consists of 2-4 layers of circumferential muscle fibre
- ## Tunica Adventitia is thick and consists of collagen fibres
Outline the histological features of the large veins, with reference to their three layers
- Tunica Intima is thin
- Tunica media contains several layers of smooth muscle separated by elastic fibres
- Tunica adventitia is thick and consists of collagen and vasa vasorum
Outline the histological features of the vena cava with reference to their three layers
- Tunica Intima is composed of fibro-elastic tissue
- Tunica Median is narrow and composed of circular smooth muscle
- Tunica adventitia is thick and consists of collagen and longitudinal smooth muscle
Identify the shape of a cardiac muscle fibre
- Long, cylindrical
Describe the number and position of cardiac muscle fibre nuclei
- One or two
- Centrally located
Are cardiac muscle fibres striated?
- Yes
What structure extends into the splenic parenchyma from the capsule?
- Trabeculae
Identify four functions of the spleen
- Production of immunological responses against blood-borne viruses
- Removal or particulate matter and defective blood cells
- Recycling iron to the bone marrow
- Haematopoiesis in the foetus
What is the splenic parenchyma?
- Splenic Cords / Cords of Billroth
- Composed of macrophages which are responsible for destruction of aged or damaged cells
What is open circulation in relation the the spleen?
- Blood cells entering parenchyma squeeze through walls of sinuses
- To drain out of organ via splenic vein
What is the peri-arteriolar lymphoid sheath?
- Cylindrical sheath in white pulp
- Consisting of T cells
- That surround a central artery
What are the follicles in the spleen?
- Areas of B cells
- That surround the peri-arteriolar lymphoid sheath
- Containing germinal centres
- Mantle zone consisting of small lymphocytes
- Marginal zone
What is the perilymphoid red pulp?
- Red pulp
- Around the marginal zone
- That contains lymphocytes
- And is devoid of sinuses
