Cardiovascular Histology Flashcards
What are the functions of the cardiovascular system ?
- delivers oxygen
- transports hormones & metabolites
- delivers nutrients
- removes waste
- maintains homeostasis
Describe the 3 layered structure of the heart
- Endocardium (inside)
- Myocardium
- Epicardium (outside)
What would you find in the Endocardium?
- squamoys epithelia
- basement membrane
What would you find in the Myocardium ?
- muscle & elastin
What would you find in the Epicardium?
- squamous epithelia
- basemement membrane
- connective tissue
- blood vessels
Define an I-band
(isotropic)
- lightest region where only actin filaments are present
Define a Z-line
- thin dark line within the I-band that anchors actin filaments
Define an A-Band
- entire length of thick filament
Define an M-line
- appears in the thin dark line withing A-band
Define a H-zone
- named for lighter region of A-band that contains myosin but no actin
What makes up the the conduction system?
- Sino-atrial node
- Atrio-ventricular node
- right bundle of His
- left bundle of His
- Purkinje Fibres
How are the atrioventricular valves connected & controlled ?
- connected to the ventricle wall by chodrae tendieae
- regulated by papillary muslces
How does Elastin Van Gieson’s stain affect heart tissue ?
- Elastin fibres = black/blue
- Nuclei = black/blue
- Collagen = red
- muscle & other = yellow
How do arteries differ from veins ?
- arteries have thicker, more muscular walls with enlarged tunica media layer
What are typically Elastic Arteries ?
- major distribution vessels
- examples = aorta, common carotid & large pulmonary
What are typically Muscular Arteries ?
- distributing branches
- Examples = radial, femoral, coronary & cerebral
What are arterioles typically?
- terminal branches
- example = supply capillary beds
Describe Elastic arteries
- arteries close to the heart must be able to expand & recoil in order to maintain a constant blood pressue throughout the heartbeat cycle
- they can do this as they contain a large number of elastic fibres
What are the 3 layers of a blood vessel ?
- tunica intima (inside)
- tunica media
- tunica adventitia (outside)
Describe Muscular Arteries
- smaller branches of elastic arteries
- contain fewer elastic fibres but more smooth muscle
- able to actively regulate blood flow to meet demand by muscular contraction
Describe Arterioles
- tunica media of arterioles is only 1/2 muscle cells thick
- responsive = vasodilate at low CO2 & vasocontrict under sympathetic stimulation
- more pressure is required to push blood through a constricted veseel than through a dilated one
- the force opposing blood flow is called resistance, hence artierioles are also known as ‘resistance vessels’
What makes up the venous system?
- larger veins, small & medium-sized veins and venules
What qualifies as a larger vein?
- major collection vessels
- examples = femoral vein, vena cava & pulmonary vein
