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
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