BIOL 1410 Lecture Notes - Lecture 12: Superior Vena Cava, Stratified Squamous Epithelium, Interventricular Septum
1 May 2018
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TOPIC 12: CARDIOVASCULAR SYSTEM
A) Cardiovascular System Overview
heart, blood vessels, blood
transport: gases, nutrients, hormones, wastes, heat
protection: disease, fluid loss (clotting)
B) Heart figure 18.2
in a cavity called the mediastinum (= space between lungs within thoracic cavity)
structure:
1) Coverings = Pericardium
double-walled sac surrounding heart – want to reduce friction
3 layers:
a) fibrous pericardium figure 18.3
outermost layer = dense irregular CT
anchors to surrounding structures e.g. diaphragm, great vessels
(aorta, vena cava, etc)
b) serous pericardium – 2 parts:
i. parietal pericardium
fused to fibrous pericardium (fibrous pericardium and
parietal pericardium = pericardial sac)
ii. visceral pericardium (= epicardium)
fused to heart surface, so is part of heart wall
between pericardial layers = pericardial cavity with serous fluid (lubricates)
2) Heart Wall
3 parts:
a) epicardium
stratified squamous epithelium and CT
b) myocardium
= cardiac muscle
arranged in spiral/circular pattern, reinforced with CT
c) endocardium
simple squamous epithelium and CT
epithelium named endothelium – lines inner surface of heart
and ALL blood vessels
3) Chambers and associated blood vessels figure 18.5e &.5d
a) Right Atrium
inferior and superior vena cava
coronary sinus (posterior)
b) Left Atrium
4 pulmonary veins
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c) Right Ventricle
pulmonary trunk – divides to form 2 pulmonary arteries
d) Left Ventricle
aorta
4) Septa (separate chambers)
a) Interatrial septum
separates atria
b) Interventricular septum
separates ventricles
deep to interventricular sulcus (external)
5) Fibrous Skeleton
CT fibers around the muscle fibers + CT rings between atria & ventricles at the
coronary sulcus (the grooves – little openings)
allows openings to remain open at all times (valves open + close)
provides electrical insulation – prevents simultaneous contraction of chambers
6) Valves
a) Atrioventricular (AV) valves:
i. bicuspid (mitral) valve
left side – 2 cusps
ii. tricuspid valve
right side – 3 cusps
Chordae tendineae (connective tissue) attach AV valve cusps to papillary
muscles (projections of myocardium)
o prevent eversion of cusps
b) Semilunar valves
3 cusps each
i. aortic
separates left ventricle + aorta
ii. pulmonary
separates right ventricle + pulmonary trunk
In lab: moderator band in right ventricle
7) Cardiac Muscle Cells figure 18.11
form BOTH contractile myocardium + conduction system
similarities to skeletal muscle:
a) striated (myofibrils with sarcomeres)
b) has sarcoplasmic reticulum & T-tubules
differences:
a) branched (myofibrils with sarcomeres) fig, 18.11 & 4.9d
b) uninucleated
c) intercalated discs = region where two fibers meet
contain anchoring and gap junctions
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8) Conduction System fig. 18.13a
cardiac muscle cells modified to produce and conduct electrical impulses – DO
NOT CONTRACT
parts:
a) sinoatrial (SA) node
in right atrium at base of superior vena cava
generates impulses the fastest – sets pace (pace maker)
b) atrioventricular (AV) node
base of right atrium
c) Atrioventricular Bundle (Bundle of His)
superior part of interventricular septum
electrically connects atria to ventricles
d) Atrioventricular (AV) Bundle Branches
go to each ventricle
e) Purkinje fibers
terminal fibers in ventricles only
Note: electrical signal spreads from conduction system to contractile cardiac cells
then they contract WON’T BE TE“TED ON
C) Circulatory Routes
We have a right and left circulatory group
closed, double circulation fig.18.1
o closed = blood confined to heart + blood vessels
o double = 2 routes (pulmonary (lungs) + systemic (whole of the system))
o chambers are part of the route
routes:
1) Adult Circulation
a) Pulmonary circulation
right ventricle to lungs via pulmonary arteries (deoxy blood)
pick up oxygen in lungs via capillaries
lungs to left atria via pulmonary veins (oxygenated blood)
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Document Summary
Topic 12: cardiovascular system: cardiovascular system overview. Protection: disease, fluid loss (clotting) transport: gases, nutrients, hormones, wastes, heat: heart figure 18. 2 in a cavity called the mediastinum (= space between lungs within thoracic cavity) Double-walled sac surrounding heart want to reduce friction. 3 layers: fibrous pericardium figure 18. 3. Between pericardial layers = pericardial cavity with serous fluid (lubricates: heart wall. Stratified squamous epithelium and ct: myocardium. Arranged in spiral/circular pattern, reinforced with ct: endocardium. Epithelium named endothelium lines inner surface of heart and all blood vessels: chambers and associated blood vessels figure 18. 5e &. 5d, right atrium. Pulmonary trunk divides to form 2 pulmonary arteries: left ventricle. Aorta: septa (separate chambers, interatrial septum. Deep to interventricular sulcus (external: fibrous skeleton. Ct fibers around the muscle fibers + ct rings between atria & ventricles at the coronary sulcus (the grooves little openings) Allows openings to remain open at all times (valves open + close)
