Chapter 11 Heart and Blood Vessels

Chapter 11
Part A: The Heart
1. Where is it?
a. Thorax between the lungs in the inferior mediastinum
b. Orientation- pointed apex directed toward left hip
c. About the size of your fist
2. Coverings
a. Pericardium- a double-walled sac
i. Fibrous pericardium is loose and superficial
ii. Serous pericardium is deep to the fibrous pericardium and composed of two layers
1. Visceral pericardium- next to the heart, also known as the epicardium
2. Parietal pericardium-
a. Outside layer that lines the inner surface of the fibrous pericardium
b. Serous fluid- fills the space between the layers of pericardium
3. Heart Structure
a. The heart wall:
i. Epicardium
1. Outside layer= visceral peridcardium
2. Connective tissue
ii. Myocardium
1. Middle layer
2. Mostly cardiac muscle
iii. Endocardium
1. Inner layer
2. endothelium
b. Heart Chambers
i. Double pump
ii. Four chambers
1. Two atria- receiving chambers
a. Right and left atrium
2. Two ventricles- discharging chambers
a. Right and left ventricle
c. Heart septa
i. Interventricular septum- seperates the two ventricles
ii. Interatrial septum
d. Heart valves
i. Purpose- allow blood to flow in and only one direction to prevent backflow
ii. Four valves
1. Atrioventricular (AV)- between atria and ventricles
a. Bicuspid (mitral) valve (left side of heart)
b. Tricuspid valve (right side of heart)
2. Semilunar- between ventricle and artery
a. Pulmonary semilunar valve
b. Aortic semilunat valve
3. AV valve details
a. Anchored in place by chordae tendineae (“heart strings”)
b. Open during heart relaxation and closed during ventricular contraction
4. Semilunar valve details
a. Closed during heart relaxation but open during ventricular contraction
b. Operate opposite of one another to force a one-way path of blood through the heart
c. Valve sequence
4. Systemic and pulmonary circulations
a. Systemic circulation- blood flows from the left side of the heart through the body tissues and back to the right side of the heart
b. Pulmonary circulation- blood flows from the right side of the heart to the lungs and back to the left side of the heart
5. Great vessels
a. Arteries
i. Aorta
ii. Pulmonary artery
b. Veins
i. Superior/inferior venae cavae
ii. Pulmonary veins
6. Blood flow through the heart
a. From venae cavae
b. From right atrium
c. From right ventricle
d. From pulmonary trunk
e. In the lungs
f. From the lungs
g. From left atrium
h. From left ventricle
7. Coronary circulation
a. Blood in the heart chambers does not nourish the myocardium
b. Coronary arteries- branch from the aorta to supple the heart muscle with oxygenated blood
c. Cardiac veins- drains the myocardium of blood
d. Coronary sinus- a large vein on the posterior of the heart, receives blood from cardiac veins
e. Blood empties into the right atrium via the coronary sinus
8. Heart conduction system
a. Intrinsic conduction system (nodal system) to coordinate pumping
b. Heart muscle cells contract, without nerve impulses, in a regular, continuous way
c. Sinoatrial (SA) node- “pacemaker” is in the right atrium
d. Atrioventricular (AV) node- is at the junction of atria and ventricles
e. AV bundle- bundles of his, is in the interventricular septum
f. Purkinje fibers spread within the ventricle wall muscles
g. Heart contractions
i. Contraction is initiated by the sinoatrial node (SA node)
ii. Sequential stimulation occurs at other autorhythmic cells
iii. Cardiac depolarization
iv. Irregularities
1. Tachycardia- rapid heart rate over 100 beats per minute
2. Bradycardia- slow heart rate less than 60 beats per minute
9. Cardiac cycle
i. Atria contract simultaneously
ii. Atria relax, then ventricles contract
iii. Systole- contraction
iv. Diastole- relaxation
b. Lubb dupp = heart sounds
i. Lubb
ii. Dupp

Chapter 11
Part B: (Mostly) Blood Vessels
1. The heart
a. Cardiac output (CO) defined: amount of blood pumped by each side (ventricle) of the heart in one minute
b. Stroke volume defined: volume of blood pumped by each ventricle in one contraction (each heartbeat)
i. Remains relatively constant
ii. 70 mL of blood is pumped out of the left ventricle/heartbeat
c. Heart rate: typically 75 beats per minute
d. CO = HR x SV
i. CO = HR (75 beats/min) x SV (70 mL/beat)
ii. CO = 5250 mL/min
iii. Starling’s law of the heart- the more the cardiac muscle is stretched, the stronger the contraction
iv. Changing heart rate is the most common way to change cardiac output
2. Regulation of heart rate
a. Increased heart rate by the
i. Sympathetic nervous system
ii. Crisis- more blood needed
iii. Low blood pressure
iv. Hormonal control:
1. Epinephrine = adrenaline
2. Thyroxine = thyroid gland, general metabolism
v. Exercise
vi. Decreased blood volume
b. Decreased heart rate by the
i. Parasympathetic nervous system
ii. High blood pressure or blood volume
iii. Decreased venous return

3. Blood vessels = the vascular system
a. General purpose- transport blood to the tissue and back
b. Classified by direction
i. Carry blood away from heart
1. Arteries
2. Arterioles = small arteries
ii. Exchanges between tissues and blood
1. Capillary beds
iii. Return blood toward heart
1. Venules
2. Veins
c. Structure of walls: three layers = tunics
i. Intima intima (inner)
1. Endothelium- simple squamous epithelium
ii. Tunic media
1. Smooth muscle, connective tissue
2. Controlled by sympathetic nervous system (involuntary)
iii. Tunic externa
1. Mostly fibrous connective tissue
d. Differences between vessels
i. Arteries
1. Walls of arteries are the thickest, more elastic
ii. Veins
1. Lumens of veins are larger
2. Larger veins have valves to prevent backflow
3. Skeletal muscle “milks” blood in veins toward the heart
iii. Capillaries
1. Walls of capillaries are only one cell layer thick of diffusion
e. Movement of blood through
i. Most arterial blood is pumped by the heart:
ii. Veins
f. Capillary beds
i. Two types of vessels
1. Vascular shunt- vessel directly connecting an arteriole to a venule
2. True capillaries- exchange vessels
ii. Oxygen and nutrients cross to cells
iii. Carbon dioxide and waste products cross into blood
iv. Materials exchanged due to concentration gradients:
1. Oxygen and nutrients leave the blood
2. Carbon dioxide and other waste leave the cells
v. Exchange mechanisms
1. Direct diffusion across plasma membranes
2. Endocytosis- things go into the cells
3. Exocytosis- things go out of the cells
4. Materials move through interstitial fluid to cells
g. Major arteries: Aorta
i. Largest artery in the body
ii. Leaves from the left ventricle of the heart
iii. Regions
1. Ascending aorta- leaves the left ventricle
2. Aortic arch- 180 to the left
3. Thoracic aorta- travels downward through the thorax
4. Abdominal aorta- passes through the diaphragm into the abdominopelvic cavity
iv. Systemic circulation:
1. Arterial branches of the aorta
v. Pulmonary circulation:
1. Branches of the pulmonary arteries
2. Study figure 11.12
h. Major veins
i. Systemic circulation
1. Superior and inferior vena cava enter the right atrium
2. Superior vena cava drains the head and arms
3. Inferior vena cava drains the lower body
i. Fetal circulation
i. Fetus receives exchanges of gases, nutrients, and wastes through the placenta
ii. Umbilical cord contains three vessels
1. Umbilical vein- carries blood rich in nutrients and oxygen to the fetus
2. Umbilical arteries (2)- carry carbon dioxide and debris-laden blood from fetus to placenta
iii. Blood flow bypass (nonfunctional) lungs
1. Blood entering right atrium is shunted directly into the left atrium through the foramen ovale (hole in septum)
2. Blood from pulmonary artery goes directly into aorta
j. Hepatic portal circulation
i. Portal circulation = extra set of veins and capillaries
ii. Veins of hepatic portal circulation drain:
1. Digestive organs
2. Spleen
3. pancreas
iii. Hepatic portal vein carries this blood to the liver
iv. Liver helps maintain proper glucose, fat, and protein concentrations in blood
4. Pulse- pressure wave of blood
a. Unit: beats/minute
b. Monitored at “pressure points” in arteries where pulse is easily palpated
c. Pulse averages 70-76 (60-100) beats per minute at rest
5. Blood pressure
a. Measured by health professionals are made on the pressure in large arteries
b. Measured with a **Sphygmomanometer**
c. Systolic- pressure at the peak of ventricular contraction
d. Diastolic- pressure when ventricles relax
e. How to write it: systolic/diastolic (120/80 mm Hg)
f. Pressure in blood vessels decreases as distance from the heart increases
g. Blood pressure: effects of factors
i. Affected by age, weight, time of day, exercise, body position, emotional state, genetics
ii. CO (cardiac output) = amount of blood pumped out of the left ventricle per minute
iii. PR (peripheral resistance) = the amount of friction blood encounters as it flows through the vesseks
1. Narrowing of blood vessels and increased blood volume increases PR
iv. BP = CO x PR
v. Neural
1. Autonomic
vi. Renal =
1. Regulated by
2. Rennin
vii. Temperature
1. Heat
2. Cold
viii. Chemicals
ix. Diet
x. Genetic predisposition
h. Variations
i. Normal
1. Systolic:
2. Diastolic:
ii. Hypotension
1. Low
2. Associated
iii. Hypertension
1. High
2. Can be