12 - Cardiovascular System

Question 1

What cavity is the heart in?

Answer 1

mediastinum (= space between lungs within thoracic cavity)

Question 2

What are the 8 ‘parts’ of the heart?

Answer 2

Pericardium
Heart Wall
The Chambers and Associated Blood Vessels
Septa
Fibrous Skeleton
Valves
Cardiac Muscle Cells
Conduction System

Question 3

Describe the pericardium

Answer 3

 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)

Question 4

Describe the heart wall

Answer 4

	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

Question 5

Describe the Chambers and Associate Blood Vessels

Answer 5

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

Question 6

Describe the Septa

Answer 6

a)	Interatrial septum
	separates atria
b)	Interventricular septum
	separates ventricles
	deep to interventricular sulcus (external) (groove on the surface)

Question 7

Describe the Fibrous Skeleton

Answer 7

 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

Question 8

Describe the Valves

Answer 8

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

Question 9

Describe Cardiac Muscle Cells

Answer 9

 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

Question 10

Describe the Conduction System

Answer 10

 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

Question 11

Describe the two circulatory routes of adult circulation.

Answer 11

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

Question 12

Describe coronary circulation.

Answer 12

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

Question 13

Does a fetus circulate it’s mothers blood?

Answer 13

NO!

Question 14

What are the three differences of fetal circulation?

Answer 14

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

Question 15

What are the three shunts in the fetal circulatory system?

Answer 15

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)

Question 16

What is the general structure of a blood vessel?

Answer 16

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!)

Question 17

What are the types of blood vessels?

Answer 17

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

Question 18

What are the characteristic features of blood?

Answer 18

o higher viscosity than H2O
o 37 oC
o pH 7.35 - 7.45
o 4 - 6 L in an adult

Question 19

Describe the composition of blood plasma.

Answer 19

	= 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

Question 20

What are the main elements of blood?

Answer 20

Plasma
RBC
WBC
Platelets

Question 21

Describe RBCs

Answer 21

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

Question 22

Describe WBCs. What are the 5 types?

Answer 22

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”)

Question 23

Describe platelets

Answer 23

 fragments of cells called megakaryocytes
 involved in clotting
 life span = ~ 10 days if not used for clotting

Question 24

What is hemopoiesis/hematopoiesis?

Answer 24

	= 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