Circulatory system histology Flashcards
Which 2 systems comprise the circulatory system?
lymphatic system
cardiovascular system
Roles of CVS system?
transport O2 & nutrients to tissues
transport CO2 & metabolic waste from tissues
temperature regulation
distribution of hormones & immune cells
reproductive function in males (penile erection)
What is the basic 3 layer structure of blood vessels?
tunica intima
tunica media
tunica adventitia
Describe the innermost layer of a blood vessel
intima
single layer squamous epithelial cells (endothelial cells supported by basal lamina + thin layer CT)
Describe the middle layer of blood vessels.
media
predominately smooth muscle
thickness varies
Describe the outermost layer of blood vessels.
adventitia
made of supporting CT
What separates the intimacy and media?
internal elastic membrane
What separates the media and adventitia?
external elastic membrane
Which arteries are the elastic arteries?
the largest ones, e.g. aorta
In which layer of the elastic arteries would the elastic fibres be found?
tunica media
What is the vasa vasorum and in which vessels would it be found?
a blood supply for the large vessels - since only the inner part of the wall can obtain nutrients from the lumen
Describe the structure of the arterioles.
only one or two layers of smooth muscle in their tunica media - almost no adventitia
Describe the structure of capillaries.
endothelial cells + basal lamina
pericytes at intervals just outside basal lamina
What are pericytes?
connective tissue cells with contractile properties
What are the 3 types of capillary?
continuous
fenestrated
sinusoidal / discontinuous
Where would you find the different capillary types?
continuous - muscle, CT, lung, skin, nerves
menstruated - gut mucosa, endocrine glands, kidney glomeruli
sinusoidal - liver, spleen, bone marrow
Which capillary type lack a basal lamina and have large gaps for macromolecules to pass through?
sinusoidal / discontinuous
What are pre-capillary sphincters composed of and where are they found?
smooth muscle
beginning of the capillary
what do capillary networks drain into?
post-capillary venules - important sites for exchange
Post-capillary venules need to acquire … before becoming venules?
intermittent smooth muscle in tunica media
What are “inward extensions of the tunica intima”?
valves in small-medium sized veins
What are the 3 layers of the heart?
Epicardium (outer)
Myocardium
Endocardium
List in order from outside to in, the layers if the heart including pericardium etc
adipose tissue fibrous pericardium pericardium parietal layer of serous pericardium pericardial cavity visceral layer of serous pericardium epicardium myocardium endocardium
What does the endocardium line?
the entire inner surface of the heart, including the valves
What are the layers of the endocardium?
(lumen of heart)
endothelial cells
fibrous tissue (basal lamina + collagen fibres)
cardiac muscle
What does the sub-endocardium contain?
loose CT containing small blood vessels + nerves + Purkinje fibres
What is the structure of the myocardium?
Bundles & layers of contractile cardiac muscle fibres
Individual muscle fibres surrounded by collagenous CT & rich network of capillaries
What is the structure of cardiac muscle cells?
single central nucleus
intercalated discs - pass across fibres at irregular intervals
What is the role of the myocytes’ intercalated discs?
attach adjacent cells and allow spread of electrical activity
What is mesothelium and in which layer of the heart is it found?
a thin layer of simple squamous epithelium
epicardium
Describe the 2 parts of the pericardium.
Fibrous - a sac pf tough fibro-collagenous CT
Serous - layer of simple squamous epithelium, basal lamina + CT
Which serous layer lines the inner surface of the pericardium?
parietal serous pericardium
Which serous layer covers the surface of the heart?
visceral serous pericardium
What separates the 2 serous layers?
pericardial cavity
What is the purpose of the pericardial fluid?
provides lubrication for heart movement
What is the lamina fibrosa and in which heart structure is it found?
core of dense CT of heart valves - is continuous with the fibrous skeleton
What are the leaflets of the mitral and tricuspid valves anchored to?
papillary muscles
How are the leaflets anchored to these muscles?
collagenous strands = chord tendinae
What are the 3 types of specialised cardiac muscle cells?
contractile cells
pacemaker cells
conducting cells
Which specialised cells appear pale?
pacemaker and conducting cells
What is the lymph vascular system?
A system of thin-walled vessels that drain excess interstitial fluid (lymph) into the bloodstream.
What produces flow through the vessels?
Smooth muscle in walls
Hydrostatic pressure in tissue
Compression of vessels by voluntary muscle + valves
