Transportation

Section 1: Blood
•
– Includes:
• Fluid (blood)
– Includes ~75 trillion cells
• Series of conducting hoses (blood vessels)
• Pump (heart)

The Components of the Cardiovascular System
THE HEART propels blood and maintains blood pressure.
BLOOD VESSELS
Capillaries
Arteries
Veins distribute blood around the body.
permit diffusion between blood and interstitial fluids.
carry blood away from the heart to the capillaries.
return blood from capillaries to the heart.
BLOOD distributes oxygen, carbon dioxide, and blood cells; delivers nutrients and hormones; transports waste products; and assists in temperature regulation and defense against disease.
Heart
Capillaries
Artery
Vein
Figure 17 Section 1 1

Section 1: Blood
•
– Transportation of dissolved gases, nutrients, hormones, and metabolic wastes
– Regulation of the pH and ion composition of interstitial fluids
– Restriction of fluid loss at injury sites
– Defense against toxins and pathogens
– Stabilization of body temperature

Module 17.1: Blood components
• Blood
– Is a fluid connective tissue
– About 5 liters (5.3 quarts) in body
• 5–6 in males, 4–5 in females (difference mainly body size)
– Consists of:
• Plasma (liquid matrix)
• Formed elements (cells and cell fragments)
– Properties
• Temp is roughly 38 ° C (100.4
° F)
• Is 5 × more viscous than water (due to solid components)
• Is slightly alkaline (average pH 7.4)

Module 17.1: Blood components
•
– Term for removed blood when composition is unaltered
• May be fractionated or separated
– Plasma
» 46%–63% of blood volume
– Hematocrit (or packed cell volume [PCV])
» Percentage of whole blood contributed by formed elements
(99% of which are red blood cells)
» Average 47% for male (range 40%–54%)
» Average 42% for female (range 37%–47%)

Module 17.1: Blood components
• Plasma
– Composition resembles interstitial fluid in many ways
• Exists because exchange of water, ions, and small solutes
• 92% water
• 7% plasma proteins
• 1% other solutes
– Primary differences
• Levels of respiratory gases (oxygen and carbon dioxide)
• Concentrations of dissolved proteins (cannot cross capillary walls)

Module 17.1: Blood components
•
– In solution rather than as fibers like other connective tissues
– Each 100 mL has ~7.6 g of protein
• ~5× that of interstitial fluid
– Large size and globular shapes prevent leaving bloodstream
– Liver synthesizes >90% of all plasma proteins

Module 17.1: Blood components
• Plasma proteins (continued)
– Albumins
• ~60% of all plasma proteins
• Major contributors to plasma osmotic pressure
– Globulins
• ~35% of all plasma proteins
• Antibodies (immunoglobulins) that attack pathogens
• Transport globulins that bind ions, hormones, compounds
– Fibrinogen
• Functions in clotting and activate to form fibrin strands
– Many active and inactive enzymes and hormones

Module 17.1: Blood components
• Plasma solutes
– Electrolytes
• Essential for vital cellular activities
• Major ions are Na + , K + , Ca 2+ , Mg 2+ , Cl – , HCO
3
– , HPO
4
– , SO
4
2–
– Organic nutrients
• Used for cell ATP production, growth, and maintenance
• Includes lipids, carbohydrates, and amino acids
– Organic wastes
• Carried to sites of breakdown or excretion
• Examples: urea, uric acid, creatinine, bilirubin, NH
4
+

Whole blood consists of
Plasma
(46–63%)
Formed elements
(37–54%)
Figure 17.1 1

Module 17.1: Blood components
• Formed elements
– Platelets
• Small membrane-bound cell fragments involved in clotting
– White blood cells (WBCs)
• Also known as leukocytes (leukos, white + -cyte, cell)
• Participate in body’s defense mechanisms
• Five classes, each with different functions
– Red blood cells (RBCs)
• Also known as erythrocytes (erythros, red + -cyte, cell)
• Essential for oxygen transport in blood

Module 17.1 Review a.
b.
c.

Module 17.2: Red blood cells
•
– Most numerous cell type in blood
• Roughly 1/3 of all cells in the body
– Red blood cell count (standard blood test) results
• Adult males: 4.5–6.3 million RBCs/1 µL or 1 mm 3 of whole blood
• Adult females: 4.2–5.5 million RBCs/1 µL or 1 mm 3 of whole blood
• One drop = 260 million RBCs

Module 17.2: Red blood cells
•
– Biconcave disc
– Average diameter ~8 µm
– Large surface area-to-volume ratio
• Greater exchange rate of oxygen
– Can form stacks (rouleaux)
• Facilitate smooth transport through small vessels
– Are flexible
• Allow movement through capillaries with diameters smaller than RBC (as narrow as 4 µm)

Stained blood smear LM x 450
Figure 17.2 1

The size and biconcave shape of an RBC
0.45–1.16 μ m
7.2–8.4 μ m
2.31–2.85 μ m
RBCs Colorized SEM x 1800
Figure 17.2 2

The advantages of the biconcave shape of RBCs
Functional Aspects of Red Blood Cells
• Large surface area-to-volume ration. Each
RBC carries oxygen bound to intracellular proteins, and that oxygen must be absorbed or released quickly as the RBC passes through the capillaries. The greater the surface area per unit volume, the faster the exchange between the
RBC’s interior and the surrounding plasma. The total surface area of all the RBCs in the blood of a typical adult is about 3800 square meters, roughly
2000 times the total surface area of the body.
• RBCs can form stacks. Like dinner plates,
RBCs can form stacks that ease the flow through narrow blood vessels. An entire stack can pass along a blood vessel only slightly larger than the diameter of a single RBC, whereas individual cells would bump the walls, bang together, and form logjams that could restrict or prevent blood flow.
• Flexibility. Red blood cells are very flexible and can bend and flex when entering small capillaries and branches. By changing shape, individual
RBCs can squeeze through capillaries as narrow as 4 μ m.
Sectional view of capillaries LM x 1430
Rouleaux
(stacks of RBCs)
Blood vessels (viewed in longitudinal section)
Nucleus of endothelial cell
Red blood cell (RBC)
Figure 17.2 3

Module 17.2: Red blood cells
• RBC characteristics (continued)
– Lose most organelles including nucleus during development
• Cannot repair themselves and die in ~120 days
– Contain many molecules (hemoglobin) associated with primary function of carrying oxygen
• Each cell contains ~280 million hemoglobin (Hb) molecules
• Normal whole blood content (grams per deciliter)
– 14–18 dL (males), 12–16 dL (females)
• ~98.5% of blood oxygen attached to Hb in RBCs
– Rest of oxygen dissolved in plasma

Module 17.2: Red blood cells
• Hemoglobin
– Protein with complex quaternary structure
– Each molecule has 4 chains (globular protein subunits)
• 2 alpha ( α ) chains
• 2 beta ( β ) chains
– Each chain contains a single heme pigment molecule
• Each heme (with iron) can reversibly bind one molecule of oxygen
– Forms oxyhemoglobin (HbO
2
) (bright red)
» Deoxyhemoglobin when not binding O
2
(dark red)

Figure 17.2 4

The quaternary structure of hemoglobin
α chain 1
β chain 2
β chain 1
Heme
α chain 2
Figure 17.2 5

The chemical structure of a heme unit
Heme
Figure 17.2 6

Module 17.2 Review a.
b.
c.

Section 1: Heart Structure
•
– Near anterior chest wall, directly posterior to sternum
– Center lies slightly to the left of midline
– Entire heart is rotated slightly left

Section 1: Heart Structure
•
– Base (superior surface where major vessels attach)
– Apex (inferior pointed tip)
– Borders
• Superior border (formed by base)
• Right border (formed by right atrium)
• Left border (formed by left ventricle and small part of left atrium)
• Inferior border (formed mainly by inferior wall of right ventricle)

The location of the heart in the chest cavity
6
5
4
7
8
9
10
3
1
2
Base
1
2
3
4
5
6
7
9
10
8
Figure 18 Section 1 1
Ribs
Apex

An anterior view showing the borders of the heart
Superior border
Right border
Left border
Inferior border
Figure 18 Section 1 2

Module 18.1: Heart wall and tissue
•
1. Epicardium (visceral pericardium)
• Covers surface of heart
• Serous membrane made of exposed mesothelium and underlying areolar tissue (attaching to myocardium)
– Parietal pericardium
• Not a heart wall layer but is continuous serous membrane with visceral pericardium
• Lines pericardial cavity and fibrous pericardial sac

Module 18.1: Heart wall and tissue
•
2. Myocardium
• Middle, muscular layer forming atria and ventricles
• Contains cardiac muscle tissue, blood vessels, and nerves
– Concentric muscle tissue layers
» Form a figure-eight around the atria
» Superficial muscle layers wrap both ventricles
» Deep muscle layers form figure-eight around ventricles

The direction of muscle bundles of the atrial and ventricular musculature
Ventricular musculature
Atrial musculature
Figure 18.1 2

Module 18.1: Heart wall and tissue
•
3. Endocardium
• Covering inner surfaces of heart, including valves
• Composed of simple squamous epithelial tissue and underlying areolar tissue
– Forms endothelium continuous with blood vessel endothelium

A section of the heart showing its three layers: epicardium, myocardium, and endocardium
Pericardial cavity
(contains serous fluid)
Myocardium
Muscular wall of the heart consisting primarily of cardiac muscle cells
Parietal Pericardium
The serous membrane that forms the outer wall of the pericardial cavity; it and a dense fibrous layer form the pericardial sac surrounding the heart
Dense fibrous layer
Areolar tissue
Mesothelium
Connective tissues
Epicardium
Covers the outer surface of the heart; also called the visceral pericardium
Mesothelium
Areolar tissue
Endocardium
Covers the inner surfaces of the heart
Endothelium
Areolar tissue
Figure 18.1 1

Module 18.1: Heart wall and tissue
•
– Compared to skeletal muscle tissue
1. Small cell size
2. Single, centrally located nucleus
3. Branching interconnections
4. Specialized intercellular connections
– Intercalated discs

A light micrograph showing the histological characteristics of cardiac muscle tissue
Intercalated discs
Cardiac muscle tissue LM x 575
Figure 18.1 3

Module 18.1: Heart wall and tissue
•
– Found only in the heart
– Cells are striated due to organized myofibrils
– Almost totally dependent on aerobic metabolism for ATP
• Large numbers of mitochondria and myoglobin to store O
2
• Has large number of capillaries to supply nutrients and O
2

Module 18.1: Heart wall and tissue
•
– Contain:
• Desmosomes
• Gap junctions
– Allow ions and molecules to move directly between cells
» Create direct electrical connection so an action potential can pass directly between cells
– Stabilize relative positions of adjacent cells
– Allow cells to “pull together” for maximum efficiency
– All cells to function “as one” (functional syncytium)

The structure of cardiac muscle cells
Cardiac muscle cells, which feature organized myofibrils, aligned sarcomeres, and numerous mitochondria
The connection of cardiac muscle cells by intercalated discs, gap junctions, and desmosomes, forming a functional syncytium
Gap junction
Intercalated Disc
Z lines bound to opposing cell membranes
Desmosomes
Size of a typical cardiac muscle cell:
10–20 μ m in diameter and
50–100 μ m in length
Intercalated disc (sectioned)
Nucleus
Mitochondria
Bundles of myofibrils
Intercalated disc
Figure 18.1 4 – 5

Module 18.1 Review a.
b.
c.

Module 18.2: Pericardial cavity
• Heart lies within pericardial cavity, a subdivision of the mediastinum
• Mediastinum also contains:
– Great vessels (entering and exiting the heart)
– Thymus
– Esophagus
– Trachea
• Because heart is closely associated with many organs, trauma can lead to fluid accumulation that can restrict heart movement (cardiac tamponade)

Two views showing the location of the heart in the chest cavity
The position and orientation of the heart relative to the major vessels and the ribs, sternum, and lungs
First rib (cut)
Trachea
Base of heart
Right lung
Diaphragm
Anterior view of chest cavity
Thyroid gland
Left lung
Apex of heart
Parietal pericardium
(cut)
A diagrammatic superior view of a partial dissection of the thoracic cavity showing the physical relationships among the components in the mediastinum
Esophagus Posterior mediastinum
Right pleural cavity
Bronchus of lung
Right pulmonary artery
Right pulmonary vein
Superior vena cava
Right atrium
Right ventricle
Right lung
Aortic arch
Anterior mediastinum
Left lung
Aorta (arch segment removed)
Left pulmonary artery
Left pleural cavity
Left pulmonary vein
Pulmonary trunk
Left atrium
Left ventricle
Pericardial cavity
Epicardium
Pericardial sac
Figure 18.2 1 – 3

Module 18.2: Pericardial cavity
•
– Lined with parietal pericardium
• Continuous with visceral pericardium (like balloon with fist in it)
– Contains 10–15 mL of pericardial fluid secreted by membranes
• Acts as lubricant when heart beats
– Swelling of pericardial surfaces can occur with infection causing friction (pericarditis)

The position and orientation of the heart relative to the major vessels and the ribs, sternum, and lungs
First rib (cut)
Trachea
Base of heart
Right lung
Diaphragm
Anterior view of chest cavity
Thyroid gland
Left lung
Apex of heart
Parietal pericardium
(cut)
Figure 18.2 1

The positions of and relationship between the heart and the pericardial cavity
The relationship between the heart and the pericardial cavity, which can be linked to a fist pressed into the center of a partially inflated balloon
Wrist (corresponds to base of heart)
Inner wall (corresponds to epicardium)
Air space (corresponds to pericardial cavity)
Outer wall (corresponds to parietal pericardium)
Balloon
Base of heart
The location of the pericardial cavity relative to the heart
Pericardial cavity containing pericardial fluid
Fibrous attachment to diaphragm
Cut edge of parietal pericardium
Fibrous tissue of pericardial sac
Parietal Pericardium
Areolar tissue
Mesothelium
Cut edge of epicardium
Apex of heart
Figure 18.2 2

Module 18.2 Review a.
b.
c.

Module 18.3: Heart surface anatomy
• Heart surface anoatomy
– Sulci (singular, sulcus)
• Surface grooves separating heart chambers
– Often with cardiac vessels covered with fat
• Anterior interventricular sulcus
– Anterior groove separating ventricles
• Posterior interventricular sulcus
– Posterior groove separating ventricles
• Coronary sulcus
– Separates atria from ventricles
– On posterior surface, contains coronary sinus (collects blood from myocardium and conveys to right atrium)

Module 18.3: Heart surface anatomy
•
– Auricles
• Expandable extensions of atria
– Ligamentum arteriosum
• Fibrous remnant of fetal connection between aorta and pulmonary trunk

Two views of the anterior surface of the heart
A diagrammatic view of the anterior surface of the heart
Aortic arch
Ascending aorta
Superior vena cava
Auricle
Right atrium
Right ventricle
Coronary sulcus
Ligamentum arteriosum
Pulmonary trunk
Auricle of left atrium
Fat
Left ventricle
Anterior interventricular sulcus
A photograph of an anterior view of a heart from a preserved cadaver
Parietal pericardium
Superior vena cava
Auricle of right atrium
Right atrium
Coronary sulcus
Right ventricle
Cadaver dissection, anterior view
Anterior surface
Ascending aorta
Pulmonary trunk
Auricle of left atrium
Anterior interventricular sulcus
Left ventricle
Figure 18.3 1 – 3

Module 18.3 Review b.
c.

Module 18.4: Coronary circulation
•
– Provides cardiac muscle cells with reliable supplies of oxygen and nutrients
– During maximum exertion, myocardial blood flow may increase to 9× resting levels
– Blood flow is continuous but not steady
• With left ventricular relaxation, aorta walls recoil (elastic
rebound), which pushes blood into coronary arteries

Module 18.4: Coronary circulation
• Coronary arteries
– Right coronary artery (right atrium, portions of both ventricles and conduction system of heart)
• Marginal arteries (right ventricle surface)
• Posterior interventricular artery (interventricular septum and adjacent ventricular portions)
– Left coronary artery (left ventricle, left atrium, and interventricular septum)
• Circumflex artery (from left coronary artery, follows coronary sulcus to meet right coronary artery branches)
• Anterior interventricular artery (interventricular sulcus)

The locations of the arterial supply to the heart
An anterior view of the coronary arteries
Right Coronary Artery
Right coronary artery in the coronary sulcus
Marginal arteries
Right atrium
Aortic arch
Left atrium
Pulmonary trunk
Right ventricle
Left ventricle
Left Coronary Artery
Left coronary artery
Circumflex artery
Anterior interventricular artery
The branches of the coronary arteries on the posterior surface of the heart
Anterior view
Arterial anastomoses between the anterior and posterior interventricular arteries
Circumflex artery
Marginal artery
Left atrium
Left ventricle
Right atrium
Posterior view
Right ventricle
Right coronary artery
Posterior interventricular artery
Figure 18.4 1 – 2

Module 18.4: Coronary circulation
•
– Great cardiac vein (drains area supplied by anterior interventricular artery, empties into coronary sinus on posterior)
– Anterior cardiac veins (drains anterior surface of right ventricle, empties into right atrium)

The major collecting vessels on the anterior surface of the heart
Anterior cardiac veins
Right atrium
Aortic arch
Left atrium
Right ventricle Left ventricle
Great cardiac vein
Anterior view
Figure 18.4 3

Module 18.4: Coronary circulation
•
– Coronary sinus (expanded vein, empties into right atrium)
– Posterior cardiac vein (drains area supplied by circumflex artery)
– Small cardiac vein (drains posterior right atrium and ventricle, empties into coronary sinus)
– Middle cardiac vein (drains area supplied by posterior interventricular artery, drains into coronary sinus)

The major collecting vessels on the posterior surface of the heart
Great cardiac vein
Coronary sinus
Left ventricle
Posterior cardiac vein
Left atrium
Posterior view
Right ventricle
Right atrium
Small cardiac vein
Middle cardiac vein
Figure 18.4 4

Module 18.4 Review a.
b.
c.

Module 18.5: Internal heart anatomy
•
– Four chambers
• Two atria (left and right separated by interatrial
septum)
• Two ventricles (left and right separated by
interventricular septum)
– Left atrium flows into left ventricle
– Right atrium flows into right ventricle

Module 18.5: Internal heart anatomy
•
– Receives blood from superior and inferior venae cavae and coronary sinus
– Fossa ovalis (remnant of fetal foramen ovale)
– Pectinate (pectin, comb) muscles (muscular ridges on anterior atrial and auricle walls)
•
– Receives blood from pulmonary veins

Module 18.5: Internal heart anatomy
•
– Receives blood from right atrium through right atrioventricular (AV) valve
• Also known as tricuspid (tri, three)
– Has three flaps or cusps attached to tendinous connective fibers (chordae tendineae)
– Fibers connect to papillary muscles
» Innervated to contract through moderator band which keeps “slamming” of AV cusps
• Prevents backflow of blood to atrium during ventricular contraction

Module 18.5: Internal heart anatomy
• Left ventricle
– Receives blood from left atrium through right atrioventricular valve
• Also known as bicuspid and mitral (mitre, bishop’s hat) valve
• Prevents backflow of blood to atrium during ventricular contraction
• Has paired flaps or cusps
– Trabeculae carneae (carneus, fleshy)
• Muscular ridges on ventricular walls
– Aortic valve
• Allows blood to exit left ventricle and enter aorta

The internal anatomy of the heart and the direction of blood flow between the chambers
Superior vena cava
Ascending aorta
Right Atrium
Receives blood from the superior and inferior venae cavae and from the cardiac veins through the coronary sinus
Fossa ovalis
Pectinate muscles on the inner surface of the auricle
Opening of the coronary sinus
Aortic arch
Pulmonary trunk
Left Atrium
Receives blood from the pulmonary veins
Left pulmonary veins
Right Ventricle
Right atrioventricular (AV) valve (tricuspid valve)
Chordae tendineae
Papillary muscle
Pulmonary valve (pulmonary semilunar valve)
Inferior vena cava
Moderator band
Interventricular septum
Left Ventricle
Thick wall of left ventricle
Left atrioventricular (AV) valve (bicuspid valve)
Trabeculae carneae
Aortic valve
Figure 18.5 1

Module 18.5: Internal heart anatomy
• Ventricular comparisons
– Right ventricle has relatively thin wall
• Ventricle only pushes blood to nearby pulmonary circuit
• When it contracts, it squeezes against left ventricle wall forcing blood out pulmonary trunk
– Left ventricle has extremely thick wall and is round in cross section
• Ventricle must develop 4–6× as much pressure as right to push blood around systemic circuit
• When it contracts
1.
Diameter of chamber decreases
2.
Distance between base and apex decreases

A sectional view of the heart showing the thicknesses of the ventricle walls and the shapes of the ventricular chambers
The relatively thin wall of the right ventricle resembles a pouch attached to the massive wall of the left ventricle
Posterior interventricular sulcus
The left ventricle has an extremely thick muscular wall and is round in cross section.
Fat in anterior interventricular sulcus
Figure 18.5 2

The changes in ventricle shape during ventricular contraction
Right ventricle
Left ventricle
Dilated (relaxed)
Contraction of right ventricle squeezes blood against the thick wall of the left ventricle.
Contracted
Contraction of left ventricle decreases the diameter of the ventricular chamber and reduces the distance between the base and apex
Figure 18.5 3

Module 18.5 Review a.
b.
d.