PATHOPHISIOLOGY II – SUMMER
TEST 1
CHAPTER 31- Structure and Function of the Cardiovascular and Lymphatic System
A. Circulatory System
a. Right Heart Function
i. Pumps blood through lungs (pulmonary circulation)
i
...
PATHOPHISIOLOGY II – SUMMER
TEST 1
CHAPTER 31- Structure and Function of the Cardiovascular and Lymphatic System
A. Circulatory System
a. Right Heart Function
i. Pumps blood through lungs (pulmonary circulation)
ii. Delivers blood to the lungs for oxygenation
iii. Low pressure system
iv. Failures common in IV drug users and back up into lungs
b. Left Heart Function
i. Pumps oxygenated blood through the systemic circulation
ii. Delivers metabolic waste products to the lungs, kidneys and liver
iii. High Pressure system
iv. Failures back up into the periphery
B. The Heart
a. Structures that Direct Circulation Through the Heart
i. Function
1. Structural Support: includes heart wall and fibrous skeleton which
encloses and supports the heart and divides it into four chambers, the
valves that direct flow, and the great vessels that conduct blood to and
from the heart
2. Maintenance of heart cells: the vessels of coronary circulation- the
arteries and veins that serve the metabolic needs of all the heart cells
3. Stimulation and control of heart action: the nerves and specialized
muscle cells that direct rhythmic contraction and relaxation, propelling
blood throughout circulation
ii. Heart wall has 3 layers:
1. Pericardium- outermost, double walled membranous sac that encloses
the heart. A surface layer of mesothelium over a thin layer of connective
tissue. The visceral layer (epicardium) is the inner layer that folds back
on itself and becomes continuous with the parietal pericardium, allowing
the large vessels to enter and leave the heart without breaching the
pericardial layers. There is a pericardial cavity that separates the layer of
the pericardium with 10-30mL of fluid secreted by mesothelium cells to
lubricate and minimize friction
a. Prevents displacement of the heart during gravitational
acceleration or deceleration
b. A physical barrier that protects the heart against infection and
inflammation from the lungs and pleural space.
c. Contains pain receptors and mechanoreceptors that can elicit
reflex changes in blood pressure and heart rate
2. Myocardium- the thickest layer of the heart composed of cardiac muscle
and is anchored to the fibrous skeleton. Thickness varies from chamber
to chamber. Biggest concern for injury to this layer
3. Endocardium- the internal lining of the myocardium composed of
connective tissue and a layer of squamous cells. The endocardial lining
of the heart is continuous with the endothelium that lines all the arteries,veins and capillaries of the body, creating a continuous, closed
circulatory system
iii. Chambers- atria are smaller than the ventricles; thickness depends on amount of
pressure or resistance it must overcome to eject blood.
1. Right atrium- 2mm thick, low pressure
2. Left atrium- 3-5mm thick, low pressure
3. Right Ventricle- 3-5mm thick; shaped like a crescent enabling it to
efficiently eject large volumes of blood through a very small valve into
the low-pressure pulmonary system
4. Left Ventricle- 13-15mm thick, high pressure; large bullet shaped, to
eject blood through a relatively large valve opening into the highpressure systemic circulation
iv. Valves- ensure one-way blood flow. The flaps/cusps are attached to the papillary
muscles by the chordae tendinae. The papillary muscles are extensions of the
myocardium that pull the cusps together and downward at the onset of
ventricular contraction.
1. Atrioventricular valves- allow blood flow from higher pressure atria to
relaxed ventricles. AS pressure increases, the valves shut to prevent
backflow. Much larger than SL
a. Tricuspid valve- 3 cusps and largest diameter
b. Bicuspid (mitral) valve- 2 cusps; The anterior cusp of the
mitral valve is continuous with the supporting tissues of the
aortic semilunar valve cusps and the left coronary valve
cusps.
2. Semilunar valves- open when intraventricular pressure exceeds aortic
and pulmonary pressures; close when pressure falls
a. Pulmonic valve- 3 cup-shaped cusps that arise from the fibrous
skeleton. Thinner cups than the aortic valve
b. Aortic valve- 3 cup-shaped cusps that arise from the fibrous
skeleton
v. Great Vessels
1. Superior an inferior Vena Cava- enter the right atrium
2. Pulmonary Artery- right and left pulmonary arteries
3. Four Pulmonary Veins- 2 from the right lung and 2 from the left lung that
carry oxygenated blood to the left atrium
4. Aorta- branches: brachiocephalic, left common carotid, left subclavian
vi. Blood Flow
1. Diastole- relaxation and blood fills the ventricles. Blood from the veins
of the systemic circulation enters the right atrium from the SVC/IVC.
Venous blood from the coronary circulation enters the right atrium
through the coronary sinus. The right atrium fills and distends, pushing
open the tricuspid valve filling the ventricle. A split second earlier, the
four pulmonary veins carry blood to the left atrium. As the left atrium
fills, it pushes the cusps of the mitral valve open and fills the left
ventricle. Left atrial contraction “atrial kick” provides significant
increase of blood to the left ventricle.
2. Systole- contraction and blood is propelled out into the circulation;
ventricular contraction
3. Cardiac Cycle Phasesa. Phase 1- Atrial systole (ventricular diastole) begins with opening
of the mitral and tricuspid valves and ventricular filling from the
atria occurs. The ventricles fill rapidly in early diastole and again
in late diastole with the atria contract
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