Histo Midterm 2 - Circulatory System

Question 1

What are the 3 tissue types in the walls of blood vessels?

Answer 1

Endothelium (simple squamous epithelium)
Muscle tissue (smooth muscle in all but capillaries)
CT (collagen and elastic fibers)

Question 2

What is the general plan of the circulatory system?

Answer 2

Heart -> Artery -> Arteriole -> Capillary -> Venule -> Vein -> Heart

Question 3

What is the structural plan of blood vessels?

Answer 3

Tunica intima
Tunica media
Tunic adventitia

Question 4

What are the 3 different types of vessels and their functions?

Answer 4

Artery - transport oxygenated blood to tissue
Vein - transport deoxygenated blood back to lungs
Capillary - moves oxygenated blood to tissue and deoxygenated blood into veins

Question 5

How do the 3 layers of the wall differ between classes

Answer 5

Tunic intima
-Internal elastic lamina (arteries/not veins)
Tunica media
-External elastic lamina (arteries/not veins)
Tunic Adventitia
-Layers of collagen 1 and elastic fibers
-Lager vessels have vasa vasorum

Question 6

What are the major characteristics of each class of artery?

Answer 6

Conducting arteries
 -Large/Elastic
Distributing arteries
 -Medium/muscular
Arterioles
 -Small arteries

Capillaries

Small Veins
-Venules
Medium Veins
Large Veins

Question 7

What are the features of large/elastic artery?

Answer 7

Locations: Aorta, Brachiocephalic, Subclavian

Tunica intima: thicker due to presence of elastic laminas

Tunica media: thick with smooth muscle, collagen, and elastic fibers

Question 8

What are the features of Medium/muscular artery?

Answer 8

Location: muscles

Tunica intima: prominent internal elastic lamina

Tunic media: 20-40 layers of smooth muscle; may have external elastic lamina

Tunica adventitia: may find lymphatics, vasa vasorum, and nerves

Question 9

What are the features of arterioles?

Answer 9

Tunica intima: thin layer; prominent internal elastic lamina

Tunic media: 10 or less layers of smooth muscle

Tunica adventitia: thin layer

Function: Regulate blood pressure and determine blood flow to tissues

Question 10

What are the features of Capillaries?

Answer 10

Function: exchange vessels (where diffusion takes place)

Tunica intima: single layer

8 micron diameter (size of RBC)

Basal lamina determines type of capillaries

Question 11

What are the variations of capillaries?

Answer 11

Continuous/somatic 
 - typical capillary
 - 2-3 endothelial cells attached via tight junctions
Fenestrated/visceral 
 -opening between endothelial cells
 -diaphragm connections
 -basal lamina continuous
 -Found in: Kidneys, other viscera
Discontinuous/sinusoidal
 -enlarged diameter
 -endothelial cells separated by spaces (no diaphragm)
 -Basal lamina discontinuous
 -found in: liver, hematopoetic tissue

Question 12

What are pericytes?

Answer 12

Specialized cells found around capillaries
In place of smooth muscle to help regulate flow
help form new blood vessels

Question 13

What are the features of Venules?

Answer 13

Tunica intima

Tunica media - pericytes

Question 14

What are the features of medium veins?

Answer 14

Irregular lumen

Tunica intima

Tunica Media

Tunica adventitia - thickest layer

Question 15

What are the features of large veins?

Answer 15

Found in: subclavian, brachiocephalic, internal jugular, vena cada

Tunica intima - well developed

Tunica media - thin

Tunica adventitia - thickest layer

May have longitudinal smooth muscle and valves (endothelium + CT)

Question 16

What is the histology of lymphatic vessels?

Answer 16

Return extracellular fluid to the bloodstream (lymph)
Circulation is one direction only (valves)
Made of: single layer endothelial cells and incomplete basal lamina
Found in: all tissue except CNS and Bone Marrow

Question 17

What are the 3 layers of the heart?

Answer 17

Endocardium
-Endothelial cells, subendothelial layer, subendocardial layer (purkinje fibers)
Myocardium
-cardiac muscle
Epicardium/visceral pericardium
-mesothelium, subepicardial layer loose CT (veins, nerves, ganglia, and adipose)

Question 18

How does cardiac muscle originate and insert?

Answer 18

Fibrous skeleton (dense CT) has distinct regions that separate artrial from ventricles

Trigone fibrosa - between aorta and atrioventricular orifices; serve as origin and insertion points for cardiac muscles

Annuli fibrosi - attachment site for atrioventricular valves

Question 19

What is the difference between macrovasculature and microvasculature?

Answer 19

Macrovasculature can be seen with the unaided eye

Microvasculature need a microscope to be seen