Histology Test Two

Front 1

Circulatory System

Back 1

blood filtrate: heart--> vessels--> capillaries (diffusion)

Components: heart, arterial system (from heart to tissues), capillaries, venous system (takes blood back to heart)

Size classification: macrovasculature (>0.1mm); microvasculature

Front 2

Circuits of Circulatory System

Back 2

Two circuits:
- pulmonary (from heart to lungs)
- systemic (from heart to body tissues)

* Portal system- connects two capillary beds

Front 3

General features of blood vessels

Back 3

3 layered walls:
1. tunica intima
2. tunica media (smooth muscle- thick in arteries, thin in veins)
3. tunica adventitia (collagen fibers run along the length- thick in veins, thin in arteries)

*Internal Elastic Lamina- underneath subendothelium (dark-staining structures)

Front 4

Components of Intima

Back 4

1. Endothelium
2. Basal Lamina
3. Subendothelium (smooth muscle associated; loose CT)

Front 5

Vaso Vasorum

Back 5

-collection of blood vessels running toward big blood vessels (ex: to the aorta)

Front 6

Nervi Vascularis

Back 6

collection of nerves

Front 7

Three Size Classes of Arteries

Back 7

1. Elastic (large)
2. Muscular (medium)
3. Small arteries and arterioles (which are even smaller)

Front 8

Elastic (large) arteries

Back 8

- Tunica Intima: multilayer- endothelial, subendothelial, internal elastic membrane (lamina)

- Tunica Media: thickest area (has elastin, smooth muscle; we get more layers as we get older. Not high diffusion rates, just transport)

- Tunica Adventitia- thin, collagen/elastic network; (vaso vasorum and nervi vascularis = innervate outer area)

Front 9

Endothelium Activation (general endothelium)

Back 9

Endothelium functions:
- selective barrier
- nonthrombogenic layer (prevents blood coagulation)
- regulation immune response
- hormone synthesis

Front 10

Muscular Arteries

Back 10

-Tunica Intima: variable (gets more thick as we get older)

- Tunica Media: thickest (smooth muscle (more muscular), little elastic)

- Tunica Adventitia: thick with external elastic lamina; vaso vasorum and nervi vascularis

Front 11

Small Arteries and Arterioles

Back 11

-Tunica Intima: about the same (endothelial and subendothelial lining; internal elastic lamina)

-Tunica Media: variable (small arteries can be 8 layers thick; arterioles can be 2 layers thick)

- Tunica Adventitia: thin and ill-defined (adventitia thinner to allow diffusion; don't need vaso vasorum, etc)

Front 12

Precapillary Sphincters

Back 12

- bands of smooth muscle around ends of arterioles that regulate flow into capillary bed (because they're delicate)

Front 13

Capillaries

Back 13

- site of exchange
- single squamous layer (so one cell layer thick) + basal lamina (basal lamina on outside)
- small diameter (could be smaller than diameter of a RBC)

Front 14

Types of Capillaries

Back 14

1. Continuous (somatic) capillaries
2. Fenestrated
3. Discontinuous (sinusoids) Capillaries

Front 15

Pericytes

Back 15

cells that lie on the outside of capillaries; maintain stability (involved in repair)

Front 16

Continuous (somatic) Capillaries

Back 16

- in muscle, lung, and CNS (not a really high gas exchange amount)
- thin cytoplasm associated; pores through basal lamina

- pericytes: cells that lie on outside of capillaries; maintain stability (involved in repair)

Front 17

Fenestrated Capillaries

Back 17

- found in sites of metabolic absorption (digestive tract, endocrine, kidney, gallbladder)
- basal lamina on outside- gaps present

- pinocytosis: thought to have created a pore completely through the cell. Allows larger things to pass thru capillary system.

Front 18

Discontinuous (sinusoids) Capillaries

Back 18

- found in liver
- gaps (holes) between cells and in basal lamina which allows even larger things to pass through
- highest level of diffusion

Front 19

Functional aspects of capillaries

Back 19

- function: regulate amount of fluid/pressure going through; vasodilators/vasoconstrictors

Front 20

Subclasses of Veins

Back 20

1. Small veins (venules)- postcapillary or muscular venules
2. Medium veins
3. Large veins

- all three tunicas present
- thinner-walled than arteries

Front 21

Venules

Back 21

*Postcapillary (where reabsorption takes place):
- basal lamina and pericytes
- no tunia media

* Muscular:
- < 1 mm diameter
- tunica media (2-3 layers)

Front 22

Medium Veins

Back 22

- Tunica intima: thin
- Tunica media: relatively thin
- Tunica adventitia: thickest (larger in veins; collagen and elastin associated)

Front 23

Artery vs Vein

Back 23

- artery: internal elastic lamina, large tunica media
- veins: smaller tunica media and larger tunica adventivia

Front 24

Large Veins

Back 24

-tunica intima: undefined
-tunica media: thin
-tunica adventitia: thickest, smooth muscle (collagen present as well)

Front 25

Fibrons Skeleton

Back 25

- made of dense CT; four rings that hold the four valves in place; also isolates atria from ventricles

Front 26

Layers of Heart

Back 26

* Endocardium:
- endothelium
- subendothelial layer

*Myocardium

*Epicardium (on outside):
- mesothelium
- subepicardium

Front 27

Valves

Back 27

*Fibrosa- dense CT core
*Spongiosa- loose CT
*Ventricularis- dense CT

Front 28

Regulation of heart beat

Back 28

- sinoatrial node (SA node)
- atrioventricular node (AV node)
- AV bundle (aka bundle of his)
- Purkinje fibers

SA node (top of right atrium)--> impulse stops (by fibrons skeleton) and AV node takes over--> impulse goes to bottom--> picked up by Purkinje fibers--> contraction