Microanatomy 2-3 Cardiovascular System

Front 1

Endocardium

Back 1

inner lining of the heart; simple squamous (endothelium) + CT

Front 2

Epicardium

Back 2

outer lining of the heart; simple squamous (mesothelium) + CT (adipose)

Front 3

Myocardium

Back 3

actual heart muscle; cardiac muscle + purkinje fibers

Front 4

What structures are continuous w/ the Endocardium's endothelium & basal lamina?

Back 4

they are continuous with endothelium of blood vessels that enter & leave the heart

Front 5

What connects the Endocardium to the Myocardium?

Back 5

Subendothelial layer of fine collagenous fibers and smooth muscle

Front 6

_____ & _____ are fibrous extensions of the endocardium.

Back 6

atrioventricular valves, chordae tendinae

Front 7

The outermost coat of the eipcardium is formed by_______ cells, a serosa (not adventitia) which releases_______.

Back 7

mesothelial, lubricating fluid

Front 8

What type of tissue is just deep to the mesothelial layer of the epicardium and what structures does it contain?

Back 8

Loose CT- mostly adipose, coronary vessels and nerves.

Front 9

What type of tissue replaces cardiac myocytes following myocardial infarction?

Back 9

After 3 days, inflammatory cells infiltrate tissue. Eventually Non-Contractile CT Scars replace the cardiac myocytes.

Front 10

Is cardiac muscle striated?

Back 10

yes

Front 11

Intercalated Discs

Back 11

“spot welds” of desmosomes & gap jnxs connecting cytoplasm of each cell to the cytoplasm of neighbors. Cardiac myocyte contraction initiates depolarization and contraction of downstream neighbors.

Front 12

Where are cardiac myocyte nuclei located?

Back 12

centrally

Front 13

Sinoatrial Node

Back 13

Pacemaker of the heart. Contains modified cardiac m. cells concentrically arranged around a Nodal Artery. Impulse spreads from this node via specialized conduction fibers to the AV node.

Front 14

Atrioventricular Node

Back 14

Located in the septal wall of the Right Atrium. Appears similar to cells of the SA node. The AV node sends impulses down the Bundle of His, which is composed of Purkinje fibers.

Front 15

Purkinje fibers

Back 15

modified cardiac muscle cells just deep to the Endocardial layer; filled with Glycogen and transmit APs much faster than cardiac myocytes

Front 16

Where do Purkinje Fibers travel in the heart?

Back 16

from the AV node to the apex of the heart while also sending branches to the right & left ventricular walls

Front 17

What is the depolarization pathway in the heart from SA node to ventricular walls?

Back 17

SA node→ R. & L. Atria
↘
AV node
↓
R. & L. Bundle Branches(purkinje fibers)
↓
R.& L. Ventricles

Front 18

What is the significance of Purkinje Fiber conduction?

Back 18

allows the heart to squeeze blood from the apex out rather than pushing blood to the apex; contraction has been described as a “wringing out.”

Front 19

What is the fnx cardiac fibrous skeleton w/ respect to insulation?

Back 19

forms layer of insulating CT that electrically isolates atria from ventricles; forms rings around the major vessels, AV canals, and the upper portion of the IV septum; prevents AP passing from atria to ventricles.

Front 20

Sympathetic input from the spinal cord via the ______nerves accelerates & strengthens heartbeat.

Back 20

cardiothoracic splanchnic

Front 21

Parasympathetic input from the_____, via the right and left _____ nerves, slows the heartbeat.

Back 21

brainstem, vagus

Front 22

Symapthetic and Parasympathetic inputs act on the ______.

Back 22

SA node

Front 23

Epinephrine/norepinephrine: released by ______ - increase speed & power of contraction

Back 23

suprarenal (adrenal) glands

Front 24

In hypertension (too much blood volume) cardiac muscle cells in the_____and______ are stretched.

Back 24

right atrium, IV septum

Front 25

In response to hypertension, myocytes release ______hormones to increase urine production as well as______hormones to dump fluid into peripheral tissues and decrease blood volume.

Back 25

diuretic, vasodilation

Front 26

Tunica Intima

Back 26

endothelium + subendothelial CT. Includes internal elastic lamina in larger vessels

Front 27

Tunica Media

Back 27

smooth muscle & external elastic lamina (in large vessels)

Front 28

Tunica Adventitia

Back 28

dense irregular CT with some elastic fibers

Front 29

Large vessels have their own blood vessels, ______, and nerves,______, in the tunica _____, which supplies deeper structures of the vessel as well.

Back 29

vaso vasorum, nervi vasorum, adventitia

Front 30

What are the 3 categories of arteries?

Back 30

Elastic (large) → Muscular (medium) → Arterioles (small)

Front 31

Elastic Arteries

Back 31

carry blood from the heart to muscular arteries

Front 32

Describe the 3 tunics of elastic arteries

Back 32

intima- Elastic fibers form an incomplete internal elastic lamina
media- thick w/ concentric elastic fiber sheets; fenestrated sheets are not the same as the external elastic lamina!
adventitia- thin w/ with elastic & collagen fibers, nerves and vessels.

Front 33

Muscular Arteries

Back 33

Deliver blood to organs.

Front 34

Describe the 3 tunics of muscular arteries

Back 34

intima- thinner than elastic aa.; well developed internal elastic lamina
media- many circular layers of smooth muscle interspersed with elastic fibers; less distinct external elastic lamina
adventitia- collagen and elastic fibers

Front 35

Which type of artery has both internal and external elastic laminae?

Back 35

muscular arteries

Front 36

Arterioles

Back 36

carry blood to tissues and capillary beds; very little subendothelial CT

Front 37

Describe the 3 tunics of Arterioles

Back 37

intima- thin; internal elastic lamina may be present
media- 1-3 layers of smooth m. w/ some elastic fibers
adventitia- thin layer of loose CT w/ longitudinally arranged collagenous & elastic fibers anchoring it to the surrounding CT

Front 38

Restenosis

Back 38

Smooth muscle cell proliferation that may occlude vessel. Occasionally follows angioplasty.

Front 39

Aneurysm

Back 39

ballooning out of artery - weakness in arterial wall. Associated with atherosclerosis, syphilis, CT disorders (Ehlers-Danlos syndrome, Marfan’s syndrome)

Front 40

Capillaries

Back 40

single layer of endothelial cells separating their lumen from surrounding tissues; almost no discernible media or adventitia although remnants remain to anchor to ECM

Front 41

Pericytes

Back 41

surround capillaries; during wound healing, may differentiate into fibroblasts or smooth m. cells

Front 42

Continuous Capillaries

Back 42

have a continuous endothelium & basal lamina; No fenestrations; Located through most of the body; contribute to CNS Blood Brain barrier tight jnxs

Front 43

Fenestrated Capillaries

Back 43

thin endothelium with large openings closed by basal lamina; located in areas that require substances to pass to/from the blood and surrounding tissues- GI tract, endocrine glands, renal glomerular tubules (no basal lamina), choroid plexus, & ciliary body

Front 44

Sinusoidal Capillaries

Back 44

discontinuous; in liver & hemopoietic organs (spleen, bone marrow). Irregular walls, wide gaps between cells, large fenestrations, incomplete basal lamina

Front 45

Trace blood flow from the heart to the body and back to the heart

Back 45

Blood from the heart follows → elastic arteries → muscular arteries → arterioles → capillaries → post-capillary venules → muscular venules → large veins → heart

Front 46

how does blood return to the heart from the periphery against gravity?

Back 46

valves in the walls of the veins and muscular compression

Front 47

Varicose Veins

Back 47

tortuous, dilated veins caused by decease in muscle tone and failure of venous valves. Blood pools and may thrombose within the vessel

Front 48

Aprrox how much of the blood volume is in the venous system?

Back 48

~70%

Front 49

Describe the tunics of veins

Back 49

intima- endothelial cells & little subendothelial CT
media- 1-2 layers of smooth muscle cells + some elastic and reticular fibers
adventita- several layers of collagen fibers that get larger as the veins expand

Front 50

which veins have valves?

Back 50

medium size veins

Front 51

Vein valves are paired, semilunar fold of______.

Back 51

intima

Front 52

What are the factors that push blood through veins back to the heart?

Back 52

muscular contraction + capillary pressure

Front 53

What are the 3 large veins?

Back 53

Superior and inferior vena cava, portal trunk

Front 54

what differentiates large veins from small veins?

Back 54

Thick tunica adventitia with collagenous fibers & longitudinal arranged smooth muscle cells

Front 55

Arteriovenous anastamoses

Back 55

connections between arterioles & venules; specialized smooth muscle sphincter in the tunica media on the arterial side of the shunt

Front 56

how does blood flow through arteriovenous anastomes when the shunt is closed?

Back 56

arterial blood flows into the capillary bed

Front 57

how does blood flow through arteriovenous anastomes when the shunt is open?

Back 57

blood bypasses capillary bed & flows into a vein

Front 58

precapillary sphincters

Back 58

control the amount of blood flowing into the capillary beds; when contracted, blood bypasses the microvascular bed carrying on down the arteriole

Front 59

Early in inflammation, macrophages in surrounding CT secrete cytokines which induce expression of _______ by endothelial cells.

Back 59

E-selectin; Neutrophils bind to selectins & then migrate through the endothelium to reach the inflamed area

Front 60

Atherosclerosis

Back 60

Foam Cell (lipid laden macrophage) formation & fatty deposits in intima, frequently due to hypercholesterolemia. These inflamed deposits may block vessel or cause blood clots to form within affected vessels. In arteries clots can break loose & lodge in the heart, brain or other tissues.

Front 61

deep venous thromboses

Back 61

clots form inside of veins due to lack of movement or from trauma to the vessel itself. Their presence results in edema since the blood cannot pass the clot easily.

Front 62

pulmonary embolism

Back 62

deep venous thrombosis breaks free from its attachment on a vein’s tunica intima, pass through the heart and then block a pulmonary artery or the entire pulmonary trunk.

Front 63

lymphatic vessels

Back 63

The fluid, proteins, enzymes, lipids, antibodies, hormones, & other macromolecules in the interstitial spaces are drained by lymphatic vessels & returned to the subclavian veins

Front 64

Approximately_____ of fluid empties into lymphatics every day.

Back 64

2-4 Liters; Exception: lymph from the brain and spinal cord drains into cerebrospinal fluid (CSF).

Front 65

Do lymph vessels have valves? Smooth m.?

Back 65

Larger lymph vessels have valves to prevent reflux and smooth muscle to propel lymph proximally

Front 66

Lymph Nodes

Back 66

Lymph vessels lead to lymph nodes where lymphatic fluid is concentrated and exposed to lymphocytes

Front 67

Lymphedema

Back 67

Blockage or destruction of these vessels leads to swelling in the regions of the body that are not getting proper drainage.