Topic 12 -Cardiovascular system Flashcards
The heart is in the area called the
mediastinum (region between lungs, within thoracic cavity)
Coverings of the heart -pericardium
double walled sac surrounding the heart -3 layers
fibrous pericardium
serous pericardium 2 layers
parietal pericardium
visceral pericardium
fibrous pericardium
(wall of cavity)
outermost layer =dense irregular CT
anchors to surrounding structures ex diaphragm
serous pericardium
what is the pericardial sac
what is the pericardial cavity
parietal pericardium -fused to fibrous pericardium
fibrous + parietal pericardium = pericardial sac
visceral pericardium= epicardium -fused to heart surface so is part of the heart wall
between pericardial layers=pericardial cavity with serous fluid
Heart wall 3 parts
epicardium
myocardium
endocardium
epicardium
=visceral pericardium
stratified squamous epithelium plus areolar CT
myocardium
=cardiac muscle
arranged in spiral or circular patter, reinforced with CT
Endocardium
=simple squamous epithelium plus areolar CT
epithelium named endothelium
lines inner surface of heart and ALL bood vessels
Chambers plus associated blood vessels
right atrium -inferior and superior vena cava, coronary sinus (posterior)
left atrium -4pulmonary veins
right ventricle -pulmonary trunk -divides to form 2 pulmonary arteries
left ventricle -aorta
Septa is made of
interatrial septum -separates atria
interventricular septum -separates ventricles, deep to interventricular sulcus (external)
sulcas=shallow groove
Fibrous skeleton of heart
CT fibres around muscle fibres + CT rings between atria and ventricles at the coronary sulcus
-allows openings to remain open at all times (valves open and close)
provides electrical insulation -prevents simultaneous contraction of atria and ventricles
atrioventricular (AV) valves
bicuspid (mitral) -left side, 2 cusps
tricuspid -right side, 3 cusps
Cordae tendineae (CT)
attach AV valve cusps to papillary muscles (projections of myocardium)
prevent eversion of cusps
semilunar valves
3 cusps each
aortic -separates left ventricle and aorta
pulmonary -separates right ventricle and pulmonary trunk
Cardiac muscle cells form both
contractile myocardium and conduction system
cardiac muscle cells are
modified/specialized=conduction systems
generates electrical signals, conduction
“normal” =myocardium -contraction
how is normal cardiac muscle cells similar to skeletal
how is it different
striated (myofibrils with sarcomeres)
has sarcoplasmic reticulum and T tubules
differences: branched, uninucleated and intercalated discs= region where two fibres meet which contain anchoring and gap junctions
Cardiac muscle cells that are modified to produce and conduct electrical impulses do not contract and have 5 parts
sinoatrial (SA) node atrioventricular (AV) node atrioventricular (AV) bundle (Bundle of His) AV bundle branches perkinje fibres
sinoatrial (SA) node
in right atrium at base of superior vena cava, generates impulses the fastest, sets pace
tells left atrium to pump
atrioventricular (AV) node
base of right atrium
atrioventricular (AV) bundle (Bundle of His)
superior part of interventricular septum
electrically connects atria to ventricles
AV bundle branches
go to each ventricle
perkinje fibres
terminal fibres
in ventricles only
electrical system spreads from conduction system to contractile cardiac cells, then they contract
Circulatory routes: closed, double circulation
closed= blood confined to heart and blood vessels double= 2 routes (pulmonary and systemic)
what is the route in adult pulmonary circulation
- right ventricle to lungs via pulmonary arteries (deoxygenated blood)
- pick up oxygen in lungs at capillaries
- lungs to left atrium via pulmonary veins (oxygenated blood)
deoxy (right ventricle->pulmonary arteries)->capillaries in respiratory portion of lungs->oxy (pulmonary veins -> left atrium)
systemic circulation
left ventricle to organs via aorta (oxy)
organs remove oxygen at capillaries
organs to right atrium via superior or inferior vena cava (deoxy)
overall route left ventricle to right atrium=systemic circulation
subdivisions of systemic circulation
cerebral=brain
hepatic=liver
coronary=heart
route of coronary circulation
left ventricle ->aorta
aorta -> right coronary artery or left coronary artery
right coronary artery-> right marginal artery or posterior interventricular artery
left coronary artery -> anterior interventricular artery or circumflex artery
all drain into different arterioles -> capillaries in myocardium-> venules->cardiac veins-> coronary sinus (blood vessel) -> right atrium
Fetal circulation
fetus gets O2, nutrients from and expel waste to mothers blood
exchanges site in placenta -blood supplies close together but do not mix
differences of fetal circulation from adult
umbilical vein lungs and liver non functional umbilical arteries (away from fetal heart)
fetal umbilical vein (toward the fetal heart)
carries oxygenated blood from placenta to vena cava
fetal shunts to bypass lungs and liver (3)
ductus venosus
foramen ovale
ductus arteriosus
as soon as baby is born the pressure differences cause the shunts to breakdown
ductus venosus (fetal)
connects umbilical vein (oxy blood) to inferior vena cava (deoxy blood) to by pass liver
permits most of the oxygenated blood coming from the placenta to bypass the liver
in vena cava oxy and deoxy mixes and enters heart via inferior vena cava
foramen ovale (fetal)
hole in interatrial septum
allows blood to move from right to left atrium to bypass the lungs
ductus arteriosus (fetal)
connects pulmonary trunk +aorta (bypass lungs)
fetal umbilical arteries
returns mixed blood to placenta
general structure of blood vessels (except capillaries)
Tunica externa -CT
Tunica media -smooth muscle, elastic fibres (CT)
Tunica interna (intima) -endothelium-simple squamous epithelium
lumen -contains blood, not layer
Arteries
2 types
carry blood away from the heart
elastic (elastic CT in all 3 tunics)
largest arteries near heart ex aorta
muscular -a lot of smooth muscle
most arteries ex coronary artery
Arterioles
little arteries
regulate blood flow and blood pressure
Capillaries
only tunica interna=endothelium (one cell layer) and basement membrane
allows exchange of gases + nutrients
gaps allow limited fluid and solutes to leak out, forming interstitial fluid (ISF)
venules
formed by uniting capillaries
interna, thin media, thin externa
bring blood toward heart
veins
large lumen
valves prevent backflow of blood
thin media -less smooth muscle
can collapse
flow of blood through vessel types
heart->elastic arteries ->muscular arteries -> arterioles -> capillaries -> venules ->veins -> heart
characteristics of blood
higher viscosity than H2O
37C
pH 7.35 to 7.45
4-6L in an Adult
composition of blood
plasma (matrix) -fluid portion with solutes
formed elements -cellular portion
plasma (matrix)
H2O 90%
proteins 8% -albumins -control tissue water balance
fibrinogen -clot formation and globulins -antibodies
other solutes 2% nutrients, hormones, wastes, electrolytes and gases
formed elements of blood
RBC -erythrocytes
WBC (leukocytes)
platelets
RBC -erythrocytes
hematocrit= % of blood volume that is RBC (~45%) biconcave disc shape anucleate when mature life span 120days destroyed in liver and spleen contain hemoglobin
hemoglobin
pigmented protein
heme=red pigment, contains iron, attaches and transports O2
globin -proteins, attaches and transports CO2
hemoglobin is broken down to heme and globin
heme is broken down to bilirubin
globin is broken down to amino acids
WBC (leukocytes)
2 types
nucleated, life span days to years, defend against disease
agranulocytes and granulocytes
granulocytes 3 types
neutrophils 60% phagocytic (engulf and digest bacteria)
eosinophils 3% attack parasites (worms)
basophils 1% release histamine to increase inflammation and heparin to decrease local clotting
agranulocytes 2 types
lymphocytes 35% immunity include T lymphocytes -kill infected cells directly and B lymphocytes become plasma cells, produce antibodies
monocytes 5% enter tissue and enlarge to become macrophages (phagocytes)
platelets
fragments of red bone marrow cells called megakaryocytes
involved in clotting
life span 2-10 days
hemopoeisis (hematopeoisis)
formation of blood cells
all blood cells arise indirectly from hemocytoblast (stem cells) in red bone marrow
red marrow in adult: axial skeleton, pelvic and pectoral girdles proximal ends of humerus and femur
