Histology Flashcards
Three major layers of the heart?
- the inner endocardium of endothelium (and subendothelial connective tissue!)
- the myocardium of cardiac muscle
- the epicardium (connective tissue with many adipocytes and covered by mesothelium)
What 4 characteristics are found in the epicardium?
- Mesothelium
- Connective tissue
- Autonomic nerve bundles
- Adipose tissue
What is the function of the cardiac conducting system?
What are the 4 parts in order?
Modified cardiac muscle fibers that stimulates rhytmic contraction (heartbeat)
- Sinoatrial (SA) node (pacemaker)
- Atrioventricular (AV) node
- Atrioventricular bundle (of His) (in interventricular septim)
- Purkinje Fibers
How do Purkinje fiber differ from contractile fibers (3)?
- larger diameter
- abundant glycogen (therefore pale staining)
- closer to the endothelium
What is the cardiac skeleton?
Three functions of the cardiac skeleton?
The cardiac skeleton is dense fibrous/irregular connective tissue primarily found in the endocardium
- anchoring and supporting heart valves
- provides firm points of insertion for cardiac muscle
- coordinates heartbeat by acting as electrical insulation between atria and ventricles
Three layers/tunics of blood vessels?
- intima
- media
- adventitia
In an artery, the thickest layer is the _1_ and the lumen is _2_. In a vein, the thickest layer is the _3_ and the lumen is _4_. In a vein, the intima forms _5_ IOT restrict backflow. _6_ contain no tunics and only endothelium.
- media
- narrow
- adventitia
- large
- valves
- capillaries
Just as the heart wall is supplied with its own _1_ arteries for nutrients and oxygen, large vessels usually have __ 2 __ (arterioles, capillaries and venules in the _3_ tunic and outer part of the media.
- coronary
- vaso vasorum
- adventitia
In arteries and large veins, the intima includes a prominent limiting layer made of elastin. What is the name of this layer?
Internal elastic lamina
3 types of microvasculature?
- Arterioles
- Capillaires
- Venules (drain capillaries)
What type of blood vessel is this?
- endothelium present
- 1-3 layers of smooth muscle
- Thin connective tissue adventitia
Arterioles
What blood vessel type is this?
- Resists and controls blood flow to capillaries
- Major determinant of systemic blood pressure
Arterioles
What type of blood vessel is this?
- Endothelium present
- Pericytes in Media
- No adventitia
Capillary
What type of blood vessel exchanges metabolites by diffusion to and from cells?
Capillaries
What type of blood vessel is this?
- Endothelium present
- scattered smooth cells in media
- no adventitia
Venule (no valves present!)
What blood vessel drains capillary beds and allows leukocytes to exit vasculature?
Venules
Flow of blood through metarterioles (smaller arteriole branches) is regulated by smooth muscle cell bands called what?
Precapillary sphincters
What is the purpose of arteriovenous shunts in skin?
They allow (through vasoconstriction) arterioles to bypass the capillary networks and connect directly to venules.