Histology Flashcards
(25 cards)
What is the functions of the CVS?
Transport oxygen and nutrients to tissues
Transport carbon dioxide and metabolic waste from the tissues
Temperature regulation
Distribution of hormones and immune cells
Reproductive function in maes- penile erection
Where is blood distributed at a given moment?
65% peripheral veins
20% heart and lungs
10% in peripheral arteries
5% in capillaries
Do the elastic membranes have perforations?
Yes
What are pericytes?
Connective tissue cells with contractile properties often found at intervals in capillaries just outside the basal lamina
What is the microvasculature?
Small arterioles connect to a post capillary venuole through a network of metarterioles, thoroughfare channels and capillaries.
What is a thoroughfare channel?
Allow shunting of blood from the arterial to venous side without passing through capillaries
What is a precapillary sphincter?
Smooth muscle sphincter at the beginning of some capillaries to help control flow through the network
What is the 3 layer structure of the heart?
Endocardium, myocardium and epicardium
What is the structure and function of the epicardium?
Lines the entire surface of the heart including the valves
Endothilium, basal lamina, thin layer of collagen and a layer of dense connective tissue. Some areas have a sub endocardium.
What is a sub endocardium and where is it found?
Lose connective tissue containing small vessels, nerves and branches of the impulse conducting system.
Occurs in the ventricular septum and contains perkinje fibres
What is the structure and function of the myocardium?
Bundles and layers of contractile cardiac muscle fibres. individual muscle fibres are surrounded by delicate, collagenous connective tissue with a rich network of capillaries.
Single central nucleus and intercollated discs to attach cells together and allow the spread of electrical activity.
What is within an intercollated disc in cardiac muscle?
Desomosome to attach intermediate fillaments Adherent junctions (zonula adherens) between actin fillaments (microfillaments) Gap junctions to allow the spread of depolarisation
What is the structure and function of the epicardium?
Outer layer of the heart
Mesothilium, basal lamina, fibroelastic connective tissue and sometimes adipose tissue
Coronary vessels are embedded in the adipose tissue on the surface of the heart
What are the 3 layers of pericardium?
Fibrous, perietal and visceral pericardium
What makes up the fibrous pericardium?
Tough fibrocollagenous tissue
What makes up the serous parietal and visceral pericardium?
Mesothilium with a basal lamia and connective tissue
What is contained in the pericardial cavity?
15-50ml of pericardial fluid providing lubrication for contraction
What is the fibrous skeleton?
Formed by bands of fibrous connective tissue around the valves, between the atria and between the ventricles.
What is the function of the fibrous skeleton?
Supports the valves and provides attachment for cardiac muscle.
Tunnel for the AV bundle is critically important
What is the structure of the heart valves?
Outer layer of endothilial cells with a basa lamina
Layer of collagen and elastic fibres
Core of dense irregular connective tissue- lamina fibrosa that is continuous with the fibrous skeleton of the heart
How are the leaflet valves anchored to the wall of the ventricle?
Papillary muscles attach to the wall of the ventricles ad chordae tendonae (collagen) attch to the papillay muscles and lamina fibrosa.
Are there any blood vessels in the valves?
No
What are the 3 types of cardiac muscle cells?
Contractile cells- 99%
Pacemaker cells- generate electrical impulse
Conducting cells- conduct impulse
NB: Pacemaker and conducting cells are specialised muscle cells NOT nerve cells
What characterises a pacemaker cell?
Smaller than a contractile cell and embedded in a more extensive matrix of connective tissue
Appear paler as they have few organelles contractile fibres and no T tubules
