15: Cardiovascular Histology Flashcards
What two systems make up the circulatory system?
Cardiovascular system - heart, arteries, capillaries and veins
Lymphatic system
Where is 65% of the body’s blood found?
Peripheral veins
Name the three fundamental layers of blood vessels, in order of inner ► outer layer.
Inner = tunica intima
Middle = tunica media
Outer = tunica adventitia
What name is given to the single layer of squamous epithelial cells lining the tunica intima of blood vessels?
ENDOthelial cells, or the endothelium
What is the tunica media composed of?
Single layer of endothelial cells
Basal lamina
Thin layer of connective tissue
What is the tunica media predominantly made up of?
Smooth muscle
What is the tunica adventitia made up of?
Connective tissue
The very largest arteries in the body are also known as ___ arteries.
elastic
Name an elastic artery found in the body.
Aorta
Why is the aorta termed an elastic artery?
It has many sheets of elastic fibres which provide elastic recoil
In large arteries, the vessles have themselves a blood supply - what is this supply called?
Vasa vasorum
You can tell that the vessels are progressing from arteries to veins because the amount of ___ ___ decreases
smooth muscle
Capillaries are often composed of just a single layer of ___ cells and a basal lamina.
endothelial
What is the name given to cells found at intervals outside the basal lamina of capillaries?
Pericytes
What are pericytes?
Connective tissue cells with contractile properties
found at intervals outside the basal lamina of capillaries
Name the three types of capillary found in humans.
Continous capillary
Fenestrated capillary
Sinusoidal / discontinuous capillary
Continous capillaries are found most / least commonly in the body.
most
Why fenestrated capillaries given that name?
Small pores in vessel wall
Where are fenestrated capillaries found?
Gut mucosa
Endocrine glands
Kidney glomeruli
Sinusoidal capillaries lack a ___ ___.
basal lamina
What can pass through the large gaps found in sinusoidal capillaries?
Macromolecules (even some cells)
Where are sinusoidal capillaries found?
Liver
Spleen
Bone marrow
Which structures, found in veins, are inward extensions of the tunica intima?
Valves
Name the three layers of the heart (superficial to deep).
Epicardium (or visceral serous pericardium)
Myocardium
Endocardium
How can cardiac muscle cells be differentiated from skeletal muscle cells?
Cardiac muscle cells tend to have a single, central nucleus (sometimes two)
Skeletal muscle cells have tons of nuclei clustered to one side of the cell
In which cells are intercalated discs found?
What is their function?
Cardiac muscle cells (cardiac myocytes)
Provide adhesion - allow tension to travel from cell-to-cell during contraction
Name three structures found within the intercalated discs of cardiac myocytes.
Desmosomes
Adherent junctions
Gap junctions
The epicardium of the heart has a single layer of flattened epithelium - what is this tissue called?
Mesothelium
Name the three layers of the pericardium
Fibrous pericardium
Parietal serous pericardium
Visceral serous pericardium
What is found in the pericardial cavity, and what function does it serve?
Pericardial fluid
Provides lubrication for heart movement
What is found on the outer part of heart valves?
Outer endothelial layer with basal lamina
What name is given to the core of dense connective tissue found within heart valves?
Lamina fibrosa
Which structures anchor the leaflets of the atrioventricular valves to the muscles in the walls of the ventricles?
What are these muscles called?
Chordae tendinae
Papillary muscles
There are three types of cardiac myocyte - what are they called?
Contractile cells (99%)
Pacemaker cells
Conducting cells
Pacemaker cells found in the AV node can be distinguised from other cardiac cells by their ___ appearance.
pale
The Purkinje fibres are much ___ than other cardiac muscle cells.
larger
Like pacemaker cells found in the AV node, Purkinje fibres also appear very ___ under the microscope.
pale
Lymphatic vessels drain tissue fluid and return it to veins - where?
In the base of the neck
