Chapter 20 - The Heart Notes for Exam

CH 20 - THE HEART


1. THE PULMONARY AND SYSTEMIC CIRCUITS
● THE PULMONARY CIRCUIT
○ Carries blood to and from gas
exchange surfaces of the lungs
○ Heart to the lungs & back to the
heart
○ Deoxygenated blood from body
enters right atrium → right ventricle
→ tricuspid valve → pulmonary valve
→ pulmonary trunk → pulmonary
arteries → lungs
■ At the lungs, the blood picks
up oxygen and does a gas
exchange of CO2
○ Oxygenated blood returns through
the pulmonary veins → left atrium →
left ventricle → aorta → the body
● SYSTEMIC CIRCUIT
○ Carries blood to and from the rest of
the body
○ Heart to the body & back to the
heart
○ Left ventricle (oxygenated blood) → aortic valve → aorta → body
■ Body (deoxygenated blood) → vena cava → right atrium
Each circuit begins and ends at the heart - blood travels through these circuits in
SEQUENCE


2. THE ANATOMY OF THE HEART
● ARTERIES
○ Carry blood AWAY from the heart
○ Artery = Away
● VEINS
○ Return blood TO the heart

, ● CAPILLARIES
○ Exchange vessels
○ Interconnect smallest arteries and smallest veins
○ Exchange dissolved gasses, nutrients, & wastes between blood and
surrounding tissues
VARIOUS ANATOMICAL STUCTURES OF THE HEART
● Pericardium: Double-layered and surrounds the heart, providing protection and
anchorage
○ Outer fibrous
pericardium
○ Inner serous
pericardium:
■ Outer PARIETAL
LAYER
■ Inner VISCERAL
LAYER
EPICARDIUM
○ The pericardial cavity:
Between the parietal and visceral layers and contains pericardial fluid
● The Heart Wall: Consists of three distinct layers
○ EPICARDIUM (Visceral layer of serous pericardium):
■ Outermost layer
■ Covers the surface of the heart
■ Covered by the
parietal layer of
serous pericardium
○ MYOCARDIUM
■ Middle layer
■ Composed of
cardiac muscle
■ Responsible for
the pumping action of the heart
○ ENDOCARDIUM
■ Covers the inner surfaces of the heart

, ■ Simple squamous
epithelium and areolar
tissues
● Heart Chambers:
○ RIGHT ATRIUM
■ Receives blood from
the SYSTEMIC
CIRCUIT
■ Receives blood from
the superior vena cava (carries blood from neck, head, upper limb,
and chest)
■ Receives blood from the inferior vena cava (carries blood from
trunk, viscera, and lower limbs)
○ RIGHT VENTRICLE
■ Pumps blood into the PULMONARY CIRCUIT
■ Has moderator band
○ LEFT ATRIUM
■ Receives blood from the PULMONARY CIRCUIT
■ Receives blood from the left and right pulmonary veins
■ Blood passes to left ventricle through the MITRAL VALVE (left AV
valve or bicuspid valve)
○ LEFT VENTRICLE
■ Pumps blood into the SYSTEMIC CIRCUIT
■ No moderator band
■ Blood leaves left ventricle through aortic valve into ascending
aorta
● The Heart:
○ Base: where the Great
Vessels connect and is
superior to the apex
○ Apex: pointed tip of the heart
inferior to the base
○ Sits between two pleural
cavities in the mediastinum