Chapter 21 - Cardiovascular System: Heart Flashcards
What kind of circuit is the heart?
Double circuit
The four characteristics of the heart
- Vital for survival
- Carries oxygen and nutrients to tissues
- Carries wastes away from tissues
- Closed system
Two circuits of the heart
Pulmonary and systemic
Functions of the pulmonary circuit
- Blood goes from heart to lungs and back
- Oxygenates blood
Functions of the systemic circuit
- Brings blood from the heart to body and back
- Delivers oxygen to tissues
Structure of the heart
- Cone shaped
- Inside PERICARDIAL CAVITY
- Inside MEDIASTINUM
- APEX tipped toward the inferior and left
- BASE superior
Double serous membrane with fibrous coat of the heart
Pericardium
Layers of the pericardium
Parietal pericardium
Epicardium
- Outer layer of pericardium
- Fibrous and areolar layer
Parietal pericardium
Another name for the epicardium
Visceral pericardium
- Inner layer of sac
- Adheres to the heart wall
Epicardium
- Between layers of heart
- Contains serous fluid
Pericardial cavity
Layers to the wall of the heart
Epicardium
Myocardium
Endocardium
Contains the visceral pericardium and functions as protective outer layer of heart
Epicardium
- Middle layer of heart
- Responsible for contractions
- Made of cardiac muscle
Myocardium
Three characteristics of the endocardium
- Inner layer
- Lines and protects chambers and valves
- Continuous with endothelium of heart vessels
Five characteristics about cardiac muscle tissue
- Striated
- Aerobic respiration
- Short T-tubules
- Connected mechanically and chemically
How does the heart connect mechanically and chemically
Intercalated discs
Gap junctions
Four chambers of the heart
2 atria
2 ventricles
What do the auricles do?
Flaps where blood pools
- Superior chambers
- Receives blood from veins
2 Atria
- Inferior chambers of the heart
- Force blood out to arteries
2 ventricles
How are the two sides of the ventricles different from each other?
- Left ventricle thicker and stronger
- Right goes only to lungs
- Left is round
- Right pouch shaped
Prevent back flow in the heart
Antrioventricular valves
- At right antrioventricular orfice
- 3 cusps
Tricuspid valve
When do the tricuspid valves open and close?
Open why atrial force is greater and closes when ventricular force is greater
- Left AV valve
- 2 cuspids
- At left atrioventricular orfice
Bicuspid valve
- Heart strings
- Hold valves in place
- Attached to cusps on ventricle side
Chordae Tendonae
What does the chordae tendonae prevent?
- Cusps from collapsing into into atria when valve is closed
- Backflow of blood
What are papillary muscles?
- Small bundles of muscles
- Attach to the chordae tendonae
- When valves close, these muscles contract and tighten cords
Scaffolding on interior walls of the ventricles
Trabeculae carneae
Valve between ventricle and artery
Semilunar valves
- Right
- At entrance to pulmonary trunk
- Opens when right ventricle contracts
Pulmonary valve
- Left
- At entrance the aorta
- Opens when left ventricle contracts
Aortic valve
Path of blood through the heart
- RIGHT ATRIUM - receives blood from superior and inferior vena cava plus coronary sinus
- RIGHT AV VALVE
- RIGHT VENTRICLE - CONUS ARTERIOSUS - funnel leading from right ventricle to pulmonary trunk
- PULMONARY VALVE
- PULMONARY TRUNK - goes to the lungs
- LEFT ATRIUM - receives blood from pulmonary veins
- LEFT AV VALVE
- LEFT VENTRICLE
- AORTIC VALVE
- AORTA - to issues
What does coronary circulation?
- Supplies the heart tissues with blood
- Blockage can result in a heart tissue dying
Branch directly off of the aorta as it emerges
Coronary arteries
Two coronary arteries
- Left coronary artery
- Right coronary artery
Components to the LCA
- Circumflex artery
- Anterior interventricular artery
Two arteries of the RCA
- Posterior interventricular artery
- Marginal artery
What do cardiac veins do?
Drain myocardium
Vein that empties into right atrium
Coronary sinus
Three cardiac veins
Great, middle, and small cardiac veins
Contractile phase; chamber empties
Systole
Relaxation phase of the heart; chambers fill
Diastole
Sounds of the heart and explanations
Lub = AV valves close Dup = semi lunar valves close
Heart beat is enabled by what cells?
- Nodal cells
- Conducting fibers
Specialized muscle cells that conduct action potentials
Nodal cells
Distributes stimulus to myocardium
Conducting fibers
What part of the heart contracts first?
Atria contract before ventricles
What causes the heart to contract unevenly?
Action Potentials
Step One of the conduction system of heart beat
SA (sinoatrial) node
- Pacemaker
- Spontaneously depolarized
- At the back wall of the right atrium
Step 2 for heartbeat
AV (Atrioventricular node)
- Where four chambers meet
- Signal transmitted to AV node through INTERNODAL PATHWAYS
Step 3 for heartbeat
AV (antrioventricular) bundle
- Transmits down interventricular septum
Stop 4 for heartbeat
BUNDLE BRANCHES
- Branches off the AV bundle
- Moves further down the septum
- One supplies each ventricle
Step 5 of heartbeat
PURKINJE FIBERS
- Reflect up external wall of ventricle
- Extend into papillary muscles
Components of the Electrocardiogram with meanings
P wave - depolarization of atria
QRS - depolarization of ventricle
T wave - repolarization of ventricle
Cardiac output of ECG/EKG
5L/min
Spontaneous contractions
Autorhythmicity
Chemical control of the heart is done how?
NE and E: Increase rate and force
Neural control of the heart is done where and with what centers?
Medull
- Cardioacceleratory centers
- Cardioinhibitory centers
Release NE/ increase HR
Cardioacceleratory centers
Release Ach/decrease HR
Cardioinhibitory centers
