Anatomy and Physiology II Study Guide (TWU)

Systemic circut
carries ovygenated blood from heart to all tissures in body except lungs and returns deoxygenated blood carrying wate products, such as carbon dioxided, back to heart

Oxygen
oxygen-rich blood ejected under high pressure out of
heart’s main pumping chamber (L. ventricle) through
largest artery (aorta)

aterioles
become progressively smaller eventually forming capillaries – blood pressure is greatly reduced

The Pulmonary Circuit
Carries blood to and from gas exchange surfaces of lungs

3 Types of Blood Vessels
Arteries: carry blood away from heart
Veins: carry blood to heart
Capillaries: networks between arteries & veins

Capillaries
Also called exchange vessels
Exchange materials between blood and tissues
Dissolved gases, nutrients, wastes

4 Chambers of the Heart
Left atrium, left ventricle, right atrium, and right ventricle

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Location of heart
Located directly behind sternum, Great veins and arteries at the base
Pointed tip is apex

The Pericardium
Double lining of the pericardial cavity

Parietal pericardium
outer layer -def
forms inner layer of pericardial sac

Visceral pericardium
inner layer of pericardium, AKA epicardium

Structure of Pericardial cavity
Is between parietal and visceral layers
contains pericardial fluid
Lubricant-reduces friction b/t heartbeats

Structure of Pericardial sac
fibrous tissue – collagen
surrounds and stabilizes heart

Pericarditis
An infection of the pericardium
Scratching sound heard due to rubbing of surfaces
Fluid collects around heart

Atria – 2
Thin-walled
Expandable outer auricle

Sulci (Coronary sulcus)
divides atria and ventricles

Sulci (Anterior and posterior interventricular sulci)
separate left and right ventricles
contain blood vessels of cardiac muscle

Epicardium
Visceral pericardium
Covers the heart
-Serous membrane
Exposed mesothelium
Areolar connective tissue

Myocardium
-Muscular wall of the heart
-Forms atria and ventricles
-Contains concentric layers of cardiac muscle tissue, blood vessels, & nerves
-Atrial myocardium wraps around great vessels

Cardiac Muscle Cells
-interconnect cardiac muscle cells
-secured by desmosomes
-linked by gap junctions
-convey force of contraction
-propagate action potentials

characteristics of cardiac muscle cells
-Small size
-Single, central nucleus
-Branching interconnections between cells
-Intercalated discs

Vena Cava
Delivers systemic circulation to right atrium

Superior vena cava
receives blood from head, neck, upper limbs, and chest

Inferior vena cava
receives blood from trunk, and viscera, lower limbs

Coronary Sinus
-Cardiac veins return blood to coronary sinus
-Coronary sinus opens into right atrium

Foramen Ovale
-Before birth, is an opening through interatrial septum
-Connects the 2 atria
Seals off at birth, forming fossa ovalis

Pectinate Muscles
-Contain prominent muscular ridges
-On anterior atrial wall
-And inner surfaces of right auricle

Cusps
-Fibrous flaps that form bicuspid (2) and tricuspid (3) valves
-Free edges attach to chordae tendineae from papillary muscles of ventricle
-Prevent valve from opening backward

Right Atrioventricular (AV) Valve
-Also called tricuspid valve
-Opening from right atrium to right ventricle
-Has 3 cusps
-Prevents backflow

Structure of Left and Right Ventricles
-Right ventricle wall is thinner, develops less pressure than left ventricle
-Right ventricle is pouch-shaped, left ventricle is round

Atrioventricular (AV) Valves
Between atria and ventricles
-One-way valves prevent backflow during contraction
-Blood pressure closes valve cusps during ventricular contraction

Papillary muscles tense chordae tendineae
prevent valves from swinging into atria

Semilunar Valves
-Pulmonary and aortic tricuspid valves
-Prevent backflow from pulmonary trunk and aorta into ventricles
-Have no muscular support
-3 cusps support like tripod

Carditis
An inflammation of the heart
Can result in valvular heart disease (VHD)

Coronary Circulation
-Coronary arteries and cardiac veins
-Supplies blood to muscle tissue of heart

Coronary arteries
-Left and right
-Originate at aortic sinuses
-High blood pressure, elastic rebound force blood through coronary arteries between contractions

Great Cardiac Veins
drains blood from area of anterior interventricular artery into coronary sinus

Anterior cardiac vein
empties into right atrium

Posterior cardiac vein, middle cardiac vein, and small cardiac vein:
empty into great cardiac vein or coronary sinus

2 type of Cardiac Muscle Cells: Conducting system
controls and coordinates heartbeat

2 type of Cardiac Muscle Cells: Contractile cells:
produce contractions

The Cardiac Cycle
-Begins with action potential at Sinoatrial (SA) node
-transmitted through conducting system
-produces action potentials in cardiac muscle cells (contractile cells)

The Conducting System
-A system of specialized cardiac muscle cells:
-initiates and distributes electrical impulses that stimulate contraction

Automaticity (conducting system)
cardiac muscle tissue contracts automatically

The Sinoatrial (SA) Node
-In posterior wall of right atrium
-Contains pacemaker cells
-Connected to AV node by internodal pathways
-Begins atrial activation (Step 1)

The Atrioventricular (AV) Node
-In floor of right atrium
-Receives impulse from SA node (Step 2)
-Delays impulse (Step 3)
-Atrial contraction begins

The AV Bundle
In the septum
Carries impulse to left and right bundle branches:
which conduct to Purkinje fibers (Step 4)
And to the moderator band:
which conducts to papillary muscles

62.Purkinje fibers
-Distribute impulse through ventricles (Step 5)
-Atrial contraction is completed
-Ventricular contraction begins

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