12 - Cardiovascular System Flashcards
What cavity is the heart in?
mediastinum (= space between lungs within thoracic cavity)
What are the 8 ‘parts’ of the heart?
Pericardium Heart Wall The Chambers and Associated Blood Vessels Septa Fibrous Skeleton Valves Cardiac Muscle Cells Conduction System
Describe the pericardium
double-walled sac surrounding heart
3 layers:
a) fibrous pericardium
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)
Describe the 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
Describe the Chambers and Associate Blood Vessels
a) Right Atrium (intake) inferior and superior vena cava coronary sinus (posterior) (gives the heart its own blood) b) Left Atrium 4 pulmonary veins (2 left, 2 right) c) Right Ventricle pulmonary trunk – divides to form 2 pulmonary arteries d) Left Ventricle aorta
Describe the Septa
a) Interatrial septum separates atria b) Interventricular septum separates ventricles deep to interventricular sulcus (external) (groove on the surface)
Describe the Fibrous Skeleton
CT fibers around the muscle fibers + CT rings between atria & ventricles at the coronary sulcus
allows openings to remain open at all times (valves open + close)
provides electrical insulation – prevents simultaneous contraction of chambers
Describe the 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
Describe Cardiac Muscle Cells
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)
b) uninucleated
c) intercalated discs = region where two fibers meet
contain anchoring and gap junctions
Describe the Conduction System
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
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
Describe the two circulatory routes of 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)
b) Systemic Circulation
left ventricle to organs via aorta (oxygenated)
organs remove oxygen via capillaries
organs to right atrium via superior + inferior vena cava (deoxygenated)
overall route: left ventricle to right atrium = systemic circulation
o subdivisions/subroutes:
cerebral = brain
hepatic = liver
coronary = heart
Describe coronary circulation.
left ventricle
- aorta
- right coronary artery (posterior interventricular artery, marginal artery) & left coronary artery (anterior interventricular artery
- circumflex artery)
- arterioles,
- capillaries in myocardium
- venules
- cardiac sinus
- coronary sinus
- right atrium
Does a fetus circulate it’s mothers blood?
NO!
What are the three differences of fetal circulation?
a) umbilical vein (towards the fetal heart)
carries oxygenated blood from placenta to vena cava
b) lungs + liver basically non-functional
3 shunts to bypass (although some blood flow to these organs for nourishment/growth):
c) umbilical arteries (away from fetal heart)
returns mixed blood to placenta
What are the three shunts in the fetal circulatory system?
i. ductus venosus
connects umbilical vein (oxy blood) to inferior vena cava (deoxy blood) to bypass liver - permits most of the oxygenated blood coming from the placenta to bypass the liver
oxy and deoxy blood mixes
mixed blood enters fetal heart via inferior vena cava
ii. foramen ovale
hole in interatrial septum
allows blood to move from the Right to Left atrium (bypass lungs)
iii. ductus arteriosus
connects pulmonary trunk + aorta (bypass lungs)
What is the general structure of a blood vessel?
1) Tunica externa – CT
2) Tunica media
smooth muscle
elastic fibers (CT)
3) Tunica intima/interna
endothelium – simple squamous epitheium
4) Lumen – contains blood (not a layer!)
What are the types of blood vessels?
1) Arteries carry blood AWAY from heart (does NOT refer to oxy or deoxy) 2 types: o elastic arteries elastic CT in all 3 layers largest arteries (near heart) e.g. aorta o muscular arteries a LOT of smooth muscle most arteries e.g. coronary artery
2) Arterioles
little arteries
regulate blood flow + blood pressure
3) Capillaries
ONLY tunica intima - endothelium (one cell layer) + basement membrane
allow exchange of gases + nutrients
gaps allow limited fluid + solutes to leak out = interstitial fluid (ISF)
capillaries unite to form….
4) Venules
intima, thin media, thin externa
5) Veins large lumen valves prevent backflow of blood thin media – less smooth muscle o can collapse
What are the characteristic features of blood?
o higher viscosity than H2O
o 37 oC
o pH 7.35 - 7.45
o 4 - 6 L in an adult
Describe the composition of blood plasma.
= blood minus formed elements composed of: a) H2O – 90% b) proteins – 8% o albumin – control tissue water balance o fibrinogen – clot formation o globulin – antibodies c) other solutes – 2% o nutrients o hormones o wastes o electrolytes o gases
What are the main elements of blood?
Plasma
RBC
WBC
Platelets
Describe RBCs
a) RBC – Erythrocytes
Hematocrit
o = % of blood volume that is RBC (~45%)
biconcave disc shape
anucleate when mature
life span – 120 days
destroyed in the liver & spleen
contain:
o Hemoglobin (pigment protein)
i. heme = red pigment – contains iron (Fe)
attaches & transports O2
ii. globin – protein
attaches & transports CO2
Hemoglobin is broken down to heme and globin
heme is further broken down to bilirubin
Fe2+ - recycled or stored (toxic, so always bound to protein)
globin to amino acids
Describe WBCs. What are the 5 types?
b) WBC – Leukocytes nucleated life span varies – days to years defend against disease 2 types: Never Let Monkeys Eat Bananas i. Granulocytes o include: neutrophils (~60%) all phagocytic (engulf + digest invaders) kill bacteria eosinophils (~3%) attack parasites (e.g. worms) basophils (~1%) Release: histamine ( inflammation) and heparin ( local clotting) ii. Agranulocytes o include: lymphocytes (~35%) - immunity 2 types: T Lymphocytes kill infected/diseased cells directly B Lymphocytes become plasma cells produce antibodies (= γ globulin) monocytes (~5%) enter tissue + enlarge to become macrophages (phagocytic = “big eaters”)
Describe platelets
fragments of cells called megakaryocytes
involved in clotting
life span = ~ 10 days if not used for clotting
What is hemopoiesis/hematopoiesis?
= formation of blood cells All blood cells arise indirectly from hemocytoblast (= stem cells) cells in red bone marrow o red marrow in adult: axial skeleton pelvic + pectoral girdles proximal ends of humerus + femur
