Cardiovascular System Flashcards Preview

Histology > Cardiovascular System > Flashcards

Flashcards in Cardiovascular System Deck (31):

Circulatory System

- one of two vascular systems in the body
- Circulates blood, uses heart as a pump


Lymphoid System

- one of two vascular systems in the body
- Unidirectional
- No pump
- Lymphatic fluid will be drained in the lymph nodes and will make its way into the circulatory system



- Lined by single layer of endothelial cells
- Connected by cell junctions
- Has a basal lamina outside around endothelial cell
- Contains pericytes around basal lamina which provide nutrients and maintain viability of endothelial cells


Continuous Capillary

- most common
- found in muscle, skin, lung and brain


Fenstrated Capillary

- Located in intestines, endocrine system, kidneys
- In the kidneys there is a thick basement membrane and no diaphragm
- have fenstrations spanned by diaphragms


Sinusoidal (discontinuous) capillaries

- Located in liver, spleen, bone marrow and endocrine system
- Contain large holes (gaps) where an entire cell can squeeze through


Capillary Exchange Mechanisms

- Open pores/gaps
- Diffusion
- Filtration
- Vesicular transport (transcytosis)
- Transendothelial channels- Vesciles join together to form a channel - allows rapid movement of cells


Vesicular Transport

- Mechanism of capillary exchange
- System of pinocytotic pits and vesicles which move large molecules across the endothelium


Secretory and Metabolic Functions of Endothelial Cells

- Adhesion molecules (diapedesis)
- Produce vasoactive compounds ( NO for vasodilation, endothelin for vasoconstriction
- Anti thrombogenic factors (anti clotting)
- Metabolic conversions (angiotensin I to II, vasoconstriction)


Tunica Intima

- Endothelium
- Connective Tissue
- Internal Elastic Lamina (IEL)


Tunica Media

- Smooth Muscle
- Elastic Fibers
- External Elastic Lamina (EEL)
- Thicker in arteries, thinner in veins


Tunica Adventitia

- Connective Tissue
- vasa vorum
- nerves
- Thinner in arteries, thicker in veins


Elastic Arteries (aorta)

- Large Lumen
- Thick tunica interna
- 40+ layers of smooth muscle in tunica media
- Thin Tunica adventitia
- A lot of elastic fibers throughout tunica media
- needs to have elasticity of aorta for it to expand and contract with the pumping of the heart


Muscular (Distributing) Arteries

- Thin tunica intima
- up to 40 layers of smooth muscle in tunica media
- thin tunica adventitia
- Internal and external elastic laminas
- elastic lamina's looked scalloped due to no longer being under pressure



- Smaller lumen
- Thin tunica intima
- 2-5 layers of smooth muscle in the tunica media
- Thin tunica adventitia
- may or may not have internal elastic lamina


Arteriovenous anastomosis

Seen in skin
- arteriole may short circuit and skip the capillary bed and go straight to venule



- seen in kidney
- ***


Venule- capillary- venule Portal system

- Seen in the liver
- ***


Venule (collecting)

- Small lumen
- Thin tunica intima
- no smooth muslce in tunica media
- Thin tunica adventitia
- no elastic lamina


Venule (muscular)

- Slightly larger lumen than the collecting venule
- thin tunica intima
- 1-2 layers of smooth muscle in tunica media
- thin tunica adventitia
- no elastic lamina


Small to medium Vein

- Larger lumen than venule
- Thin tunica intima (with valves)
- Thin or absent tunica media
- Thick tunica adventitia
- Internal elastic lamina (vague) (almost non existent)


Large Veins (vena cava)

- Large Lumen
- Thick tunica intima
- Thin (several layers) of smooth muscle in tunica media (smooth muscle runs planar)
- Thick tunica adventitia with longitudinal smooth muscle bundles (runs perpendicular to the smooth muscle in tunica media)
- Internal elastic lamina
- Contains vasa vasorum which are blood vessels within blood vessels providing nutrients


Valves in Veins

- Facilitate unidirectional blood flow in veins


Evolution of the Heart

- Fish- mixing of oxy and deoxygenated blood
- Amphibians- separtaion of atria- still some mixing
- Reptiles- partial separation of ventricles and partial separation of oxy and deoxy blood
- Mammals- total separation with 4 chambers


Structure of the heart

- built on a cardiac skeleton of high density collagen connective tissue
- 3 layers
1) Endocardium (inner lining)- homologous to tunica intima
2)Myocardium- homologous to tunica media
3) Epicardium (outer surface)- homologous to tunica adventitia
- Resides in a sac called the pericardium


Purkinje Fibers

- In the endocardium
- facilitate the signaling events that regulate the contraction of the heart


Signal Transduction through the heart

- Sinoatrial node (SA node)- pacemaker of the heart, continuously releases a wave of depolarization
- this is sent to the atrioventricular node (AV node)
- It is then sent to the bundle of His
- Then to purkinje fibers
- Apex of the heart is the first to receive the wave of depolarization


Lympatic System Functions

- return excess 10% of interstitial fluid to blood
- Transport lipids absorbed from intestines
- Immunologic support


Lymphokinetic Motion and Pressure Gradient

Blood Capillaries (highest pressure)---> Interstitial fluid---> Lymph capillaries---> Lymph veins---> Lymph ducts---> Large circulatory veins, vena cava (lowest pressure)


Lymphatic capillaries

- have unique permeability characteristics, filaments (elastic fibers)
- anchor to connective tissue


Lymph Nodes

- All lymph gets filtered by at least one lymph node before it re enters the blood