3.10b Microanatomy of the Lymphatic and Heart

Question 1

Valves:

Answer 1

-in all types of venules that carry blood against gravity
-prevent backflow of blood
*folds of interna with core of collagen fibers

Question 2

Sensory receptors:

Answer 2

-carotid body in the junction between internal and external carotid artery
>detects changes in BP, O2 and CO2 levels

Question 3

Lymphatic system:

Answer 3

-circulatory and defensive functions

Question 4

Lymph capillaries:

Answer 4

-lined by very thin endothelium, larger than capillaries
-mainly present in loose CT
-junctional complexes are weak
-basal lamina is absent or discontinuous

Question 5

Junctional complexes of lymph capillaries:

Answer 5

-weak
>create gaps between cells and close them easily as/when required

Question 6

Outer surfaces of endothelium of lymph capillaries:

Answer 6

-connected to collagen and elastic fibers
>helps to keep the lumen open

Question 7

Lymph capillaries absent in:

Answer 7

-CNS
-eyeball
-bone marrow
-red pulp of spleen
-liver lobule
-tonsils

Question 8

Small and medium lymph vessels:

Answer 8

-larger diameter
-one or two layers of smooth muscle cells and elastic fibers
-tunica externa is not distinguishable from surrounding CT

Question 9

Large lymph vessel:

Answer 9

-have TI, TM, and TE, but no well delineated
-internal elastic membrane is absent

Question 10

Valves of lymph vascular system:

Answer 10

-present in all lymph vessels (capillaries may not have)
-endothelial fold with very little CT core
-CT is more at the junction with the vessel wall

Question 11

Heart layers:

Answer 11

-endocardium
-myocardium
-epicardium
-pericardium

Question 12

Endocardium:

Answer 12

-lines inside of heart
-3 layers
-cardiac valves
-impulse generation and conduction

Question 13

3 layers of endocardium:

Answer 13

-endothelium: innermost
-inner subendothelial layer
-outer subendothelial layer

Question 14

Inner subendothelial layer of endocardium:

Answer 14

-dense irregular CT with collagen and elastic fibers
-occasional smooth muscles

Question 15

Outer subendothelial layer of endocardium:

Answer 15

-loosely arranged collagen and elastic fibers
-Purkinje fibers
-adipose cells
-lymph and blood supply

Question 16

Cardiac valves:

Answer 16

-endocardial folds
>dense irregular CT covered by endothelium
1. AV valves
2. Semilunar valves

Question 17

Atrioventricular (AV) valves:

Answer 17

-collagen fibers predominate and connect with fibrous rings and chordae tendinea
-central layer is covered by elastic fibers

Question 18

Semilunar valves:

Answer 18

-connective tissue fibers are circularly arranged
-elastic fibers are thin towards blood vessels, thick towards the ventricular surface
-free edge is thick

Question 19

How is the free edge of semilunar valves thick:

Answer 19

-presence of loose CT and cartilage

Question 20

Impulse generation through:

Answer 20

-SA node and AV node

Question 21

SA node is a network of:

Answer 21

> thin branching nodal muscle cells
scare muscle fibers
no intercalated discs
-continue with cardia muscle fibers of atrial myocardium

Question 22

SA node contains:

Answer 22

-many autonomic nerve fibers and occasional ganglion cells

Question 23

AV node:

Answer 23

-similar morphology to SA node, but nodal muscle fibers are continuous with both atrial myocardial fibers and impulse conducting cardiac fibers
>*form atrioventricular bundle

Question 24

Myocardium:

Answer 24

-thickest layer of the heart

Question 25

Myocardium contains

Answer 25

-bundles of cardiac muscle cells
-impulse generating and conducting system
-cardiac skeleton

Question 26

Cardiac muscles in CT with (myocardium)

Answer 26

-dense capillary network
-lymph vessels
-autonomic nerve fibers

Question 27

Atrial cardiac muscles (myocardium):

Answer 27

-smaller than ventricular
-have atrial natriuretic peptide (fluid homeostasis)

Question 28

Cardiac skeleton contains:

Answer 28

-fibrous rings
-fibrous triangle
-fibrous (membranous) part of interventricular septum

Question 29

Fibrous rings:

Answer 29

-annuli fibrosi
-at AV openings and pulmonary and aortic openings
-bundles of collagen and elastic fibers

Question 30

Fibrous triangle:

Answer 30

-trigonum fibrosum
-CT between AV openings and base of aorta
>dense irregular CT (pig and cat)
>fibrocartilage (dog)
>hyaline (horse)
>bone (large ruminants)

Question 31

Fibrous (membranous) part of interventricular septum:

Answer 31

-collagen bundles

Question 32

Epicardium:

Answer 32

-covered externally by visceral pericardium
>layer rich in elastic fibers under it
-more abundant around large subepicardial blood vessels
-continues with parietal pericardium at the orifice (opening) of large blood vessels

Question 33

Layer of rich elastic fibers: epicardium

Answer 33

-protects blood vessels and nerves

Question 34

Pericardium:

Answer 34

-thick layer of collagen bundles and elastic fibers
-covered with mesothelial layers:
>parietal layer of pericardium (inner)
>mediastinal pleura (outer)

Question 35

Pericardial cavity:

Answer 35

-space between visceral and parietal layers
-contains serous fluid
>easy movement of the heart