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Anatomy 2 Unit 3 > 9 - Circulatory System Histology > Flashcards

9 - Circulatory System Histology Flashcards

1
Q

Major Function cardiovascular system

A

Transportation
Nutrients and Oxygen
Waste Products
Hormones

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2
Q

Left Side of Heart

A

Pump for the systemic circuit

Left Atrium – receives oxygenated blood

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3
Q

Right Side of Heart

A

Pump for the pulmonary circuit

Right Atrium – receives deoxygenated blood

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4
Q

The heart wall contains:

A

Cardiac muscle
Fibrous skeleton on the heart
Fibrous rings (4) that surround the valve orifices
Fibrous trigones (2) connecting the fibrous rings
Membranous portion of the interventricular and interatrial septa
Conducting system
Coronary vasculature
Serous membrane
Endothelial cells with underlying connective tissue

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5
Q

Epicardium –

A

outer layer

also known as the visceral layer of serous pericardium

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6
Q

Myocardium –

A

middle layer
composed primarily of the cardiac muscle
also contains the fibrous skeleton of the heart

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7
Q

Endocardium –

A

inner layer
Three components:
Endothelial cells – inner layer
Subendothelial Layer – middle layer; contains connective tissue & smooth muscle cells
Subendocardial layer – deeper layer; connective tissue layer containing the intrinsic conduction system

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8
Q

Two Atrioventricular Valves

A

(prevent backflow into atria):

1) Tricuspid Valve
2) Bicuspid or Mitral Valve
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9
Q

Two Semilunar Valves

A

(prevent backflow into ventricles):

1) Aortic Semilunar Valve
2) Pulmonary Semilunar Valve
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10
Q

Heart valves enforce one way blood flow through the heart and open/close in response to

A

pressure changes.

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11
Q

There are NO valves associated with

A

entrances of venae cavae, coronary sinus, and pulmonary veins into the heart!

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12
Q

Histology of Heart Valves:

A

Composed of connective tissue with overlying endocardium

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13
Q

Spongiosa –

A

loose connective tissue covered in endothelium; located on atrial or blood vessels side of valve; loosely arranged collagen and elastic fibers infiltrated with proteoglycans; shock absorber.

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14
Q

Fibrosa –

A

core of valve; contains fibrous extensions from the dense irregular connective tissue of skeletal rings of heart.

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15
Q

Ventricularis –

A

dense connective tissue with layers of elastic fibers covered in endothelium; adjacent to ventricular side of the valve.

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16
Q

The cardiac muscle of the heart is able to depolarize and contract without

A

impulses from the nervous system. Its ability to do so is because of the intrinsic cardiac conduction system.

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17
Q

Composed of the 1% noncontractile cardiac cells called

A

cardiac conducting cells or autorhythmic cells as they are self-excitable, meaning they can generate an action potential without nervous system input.

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18
Q

Two types of cardiac conducting cells:

A

Nodal cardiac cells
Purkinje fibers

These cells are organized into nodes and highly specialized conducting fibers/tracts.

These cells are responsible for the initiation and distribution of impulses throughout heart.

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19
Q

The rate of the intrinsic cardiac muscle contraction set by these pacemaker cells is altered by the

A

sympathetic (accelerates the heartbeat) and by the parasympathetic (decelerates the heartbeat) divisions of the autonomic nervous system; hormones can also impact intrinsic rate.

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20
Q

The following is the excitation sequence that takes place in collections of autorhythmic cardiac cells:

A
  1. Sinoatrial Node – pacemaker of heart; determines heart rate through its sinus rhythm. (Why?)
    ↓↓↓
    2) Atrioventricular Node – impulse travels to the atrioventricular node via the internodal pathway or tracts; impulse delayed here for ~0.1s to allow for the atria to contract.
    ↓↓↓
    3) Atrioventicular Bundle or Bundle of His – impulse travels from atrioventricular node to the right and left bundle branches; only electrical connection between atria and ventricles; travels across the fibrous skeleton.
    ↓↓↓
    4) Right and Left Bundle Branches – branches of the atrioventricular bundle; course toward apex of heart through interventricular septum.
    ↓↓↓
    5) Purkinje Fibers (a.k.a. Subendothelial Branches) – finish pathway in interventricular septum, around apex of heart, and head back towards atria.
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21
Q

Nodal Cardiac Muscle Cells : Found in the

A

SA and AV nodes

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22
Q

Nodal Cardiac Muscle Cells : Modified

A

cardiac muscle cells

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23
Q

Nodal Cardiac Muscle Cells : Smaller than surrounding

A

atrial contractile cardiac cells

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24
Q

Nodal Cardiac Muscle Cells : Contain fewer

A

myofibrils and lack intercalated discs

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25
Purkinje Fibers: Found in
AV bundle, bundle branches, and subendothelial branches See “Shotgun Histology Heart Purkinje Fibers” at
26
Purkinje Fibers: Modified
cardiac muscle cells
27
Purkinje Fibers: Larger than surrounding
ventricular contractile cardiac cells
28
Purkinje Fibers: Contain myofibrils at
periphery of cell
29
Purkinje Fibers: Nuclei are
round and larger than nuclei of regular cardiac fibers | Have associated intercalated discs
30
Purkinje Fibers: Positive for PAS staining because of large amount of
glycogen | With H&E – glycogen-rich center of cell appears homogenous and stains pale
31
The walls of blood vessels (except the smallest) have three layers or tunics:
interna, media, externa
32
Tunica Interna or Tunica Intima | 3 parts
Three Parts: a. endothelium b. basal lamina c. subendothelial layer (internal elastic membrane – arteries and some arterioles
33
Tunica Media – contains
rings of smooth muscles cells responsible for vasoconstriction and vasodilation; can also contain sheets or lamellae or laminae of elastin (external elastic membrane – arteries)
34
Tunica Externa or Tunica Adventitia – in larger vessels this tunic contains a
vasa vasorum and a nervi vascularis
35
In cross section, arteries will appear more
open and veins more collapsed. Additionally, the lumen of the vein is much larger than that of the comparable artery.
36
Arteries – thickest layer is the
tunica media
37
Veins – thickest layer is the
tunica externa
38
Elastic or Conducting Arteries (Large Arteries) –
largest diameter arteries (diameter greater than 10mm); walls contain large amounts of elastic fibers; allows arteries to expand and recoil; important vessels in helping to propel blood onward while ventricles are relaxing; elastic fibers function as pressure reserve.
39
Muscular or Distributing Arteries (Medium Arteries) –
medium-sized arteries (2mm to 10mm diameter); walls contain large amounts of smooth muscle; important in regulating the blood flow to specific body regions; smooth muscle cells in circular orientation and are responsible for vasoconstriction (i.e. reduction in lumen diameter) and vasodilation (i.e. increase in lumen diameter).
40
Small Arteries –
0.1mm to 2mm in diameter; as many as eight layers of smooth muscle in their tunica media.
41
Arterioles –
smallest diameter artery; 10m to 100m diameter; only one or two layers of smooth muscle in the tunica media.
42
Elastic or Conducting Arteries (Large Arteries) – dia. greater than
10mm Tunica intima – has an inconspicuous internal elastic membrane Tunica media – thickest layer; consists of multiple layers of smooth muscle cells separated by elastic lamellae Tunica adventitia – thin; may contain a vasa vasorum and nervi vascularis
43
Muscular or Distributing Arteries (Medium Arteries) – dia. 2mm to 10mm
Tunica intima – thinner than that of elastic arteries; has a prominent internal elastic membrane. Tunica media – thickest layer; consists almost entirely of multiple layers of smooth muscle cells separated limited elastic material; has a prominent external elastic membrane. Tunica adventitia – relatively thick; may contain a vasa vasorum and nervi vascularis.
44
Small Arteries – dia. 0.1mm to 2mm
Tunica intima – typically has an internal elastic membrane Tunica media – as many as eight layers of smooth muscle Tunica adventitia – thin, ill defined
45
Arterioles – dia. 10m to 100m
Tunica intima – may or may not have an internal elastic membrane Tunica media – only one or two layers of smooth muscle Tunica adventitia – thin, ill defined
46
Capillaries
Smallest diameter of blood vessels; 4μm-10μm. Thin wall – endothelial cell and its basal lamina. Their main role is to allow the exchange of materials between the blood and body tissues.
47
Three types of capillaries based on their morphology:
Continuous capillaries Fenestrated capillaries Discontinuous capillaries (a.k.a. sinusoidal capillaries or sinusoids)
48
Continuous Capillaries
Found in muscle, lung, and central nervous system Uninterrupted endothelial cell lining with tight or occluding junctions See pinocytotic vessels May see associated pericytes
49
Fenestrated Capillaries
Found in endocrine glands and at sites of fluid and metabolite absorption Have oval pores (80nm to 100nm in diameter) called fenestrations See pinocytotic vessels
50
Discontinuous Capillaries (a.k.a. sinusoidal capillaries or sinusoids)
Found in the liver, spleen, and bone marrow | Larger diameter and more irregularly shaped than other capillaries
51
The flow of blood from an arteriole through a capillary network to a postcapillary venule is called
microcirculation. Three items (i.e., the arteriole, the capillary network, and the postcapillary venule) form a functional unit called the microcirculatory bed or microvascular bed.
52
Two Types of Vessels in the Capillary Network:
True Capillaries Arteriovenous (AV) Anastomoses or Shunts (a.k.a. Metarteriole-Thoroughfare Channel)
53
The More the Precapillary Sphincters Relax (and the smooth muscle of the AV shunt contract)  the more
blood will pass through the true capillaries in the capillary beds.
54
The More the Precapillary Sphincters Contract (and the smooth muscle of the AV shunt relax)  the more
blood will pass through the arteriovenous anastomoses and bypass the true capillaries.
55
There are four types of veins:
venule, small, med large
56
Venule –
smallest diameter veins (diameter of 10μm to 100 μm); receive blood from capillaries; two types: Postcapillary Venule – endothelial cell with basal lamina and pericytes; no tunica media and no adventitia. Muscular Venule – possess a tunica media with one or two layers of smooth muscle and a thin tunica adventitia; typically no pericytes here.
57
Small Veins – 0.1mm to 1mm in diameter; receive
blood from muscular venule.
58
Medium Veins – 1mm to 10mm in diameter; all
three layers present.
59
Large Veins – larger than 10mm in diameter;
all three layers present
60
Medium Veins – dia. 1mm to 10mm
Tunica intima – endothelium and its basal lamina, thin subendothelial layer with an occasional smooth muscle cell, and, in some cases, a thin internal elastic membrane. Tunica media – thinner than the associated artery; several layers of smooth muscle (most circularly arranged, with the occasionally longitudinally arranged) with interspersed collagen and elastic fibers. Tunica adventitia – thicker than the intima and media; collagen and networks of elastic fibers.
61
Large Veins – dia. greater than 10mm
Tunica intima – endothelium and its basal lamina, along with thin subendothelial layer with some smooth muscle cells. Tunica media – relatively thin; circularly arranged smooth muscle cells Tunica adventitia – thicker than the intima and media; collagen and elastic fibers with an occasional smooth muscle cell.
62
Most veins in limbs have valves (i.e.,
thin folds of tunica intima; endothelial cells over a thin layer of connective tissue) that prevent backflow of blood.
63
Serous membrane formed by
specialized squamous epithelium - mesothelium on loose connective tissue
64
Pericardium viscera has
nerves and blood vessels
65
Subendocardial layer has
conduction - purkinje fibers found here
66
IF you look at heart anteriorly, pulmonary trunk in front
looks a bit like a T
67
Spongiosa facing outflow is
arterialis
68
Atria spongiosa
auricularis **
69
Spongiosa collagen dampens
vibration of valve opening and closing
70
AV BUNDLE OF HIS
ONLY ELEcrtical signal between atrium and ventricle - no gap junctions between cells of atrium and ventricle
71
If SA node is damaged, than
AV node takes over
72
Tunica interna- internal elastic membrane
exactly as it sounds, at the interior of some tunica internas (usually on larger arteries/veins)
73
external elastic membrane
between tunica media and externa
74
Endothelium long axis in the direction of
bloodflow
75
Muscular arteries external elastic membrane
a bit sporadic - fibers in many different directions
76
continuous capillaries
have pinocytotic vessels carry things across ONLY
77
Pericytes in
basal lamina - unspecialized stem cell. Can form endothelial or smooth muscle cells - in continuous cap, help in vessel growth.

Anatomy 2 Unit 3 (14 decks)

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