Cardiovascular System Flashcards
Learning Outcomes:
- Describe the anatomy of the heart and identify the gross anatomical features including the great vessels and the vessels supplying and draining the heart.
- Describe the cardiac cycle.
- Relate an ECG to the electrical and mechanical changes occurring in the heart
during the heart cycle. - Define cardiac output and describe the effect of the autonomic nervous
system on heart rate and stroke volume. - Describe the structure of blood vessels.
Cardiovascular system
Cardiovascular system = heart and blood vessels
Circulatory system = heart, blood vessels, and blood
Functions of circulatory system:
* Transport
* 02, CO, nutrients, wastes, hormones
* Protection
* Regulation
* citainmation, limit spread of infection, destroy microrganisms and cancer cell, neutralize toxins, and initiate
* Fluid balance, stabilizes pH of extracellular fluid (ECF), and temperature control
The Pulmonary & Systemic Circuits
2 major divisions of circulatory system:
* Systemic circuit:
* Supplies oxygenated blood to all tissues of the body and returns it to the heart
* Pulmonary circuit:
* Carries blood to lungs for gas exchange and back to heart
Position of the Heart
in the thoracic cavity
posterior to the sternum
Anterior to the vertebral column
Medial to the lungs
: In the mediastium
Surrounded by the pericardium
Position of the Heart
The Pulmonary & Systemic Circuits photo
Blood flow
Basic plan:
2 pumps: right & left
Each pump has 2 chambers
Ventricles pump blood
atria receive blood
* Valves ensure blood flows in one direction only
arteries take blood away from the heart
Veins carry blood back to heart
Capillaries are small vessels connecting arteries to veins
Heart chambers photo
Posterior view of the heart photo
Anterior view of the heart photo
Blood Flow photo
Coronary circulation
5% of blood pumped by heart goes to the heart itself through the coronary circulation.
* Heart needs abundant O, and nutrients to sustain its workload.
* Most coronary blood returns to R atrium via the coronary sinus. (Some returns directly into R ventricle via cardiac veins.)
Coronary circulation photo
Valves
Eletrocardiogram (ECG or EKG)
“Lub-dub”
Ventricles contract:
* internal pressure rises
* AV valves close = “Lub”’
* semilunar valves pushed open
* blood flows into aorta and pulmonary trunk
Ventricles relax:
* expand & internal pressure falls
* Semilunar valves close as blood attempts to flow
back into the ventricles from the vessels = “Dub”
* AV valves open: blood flows from the atria into the ventricles.
“Lub-dub” photo
Valves
Pericardium
- Double-walled sac that encloses the heart
- Allows heart to beat without friction, provides room to expand, yet resists excessive expansion
- Anchored to diaphragm inferiorly and sternum anteriorly
- Fibrous pericardium: Outer wall, not attached to heart
- Serous pericardium
- Parietal layer: lines fibrous pericardium
/. Visceral layer (epicardium): covering heart surface
** Pericardial cavity-space between parietal and visceral layers of serous pericardium, filled with pericardial fluid
peri = around; cardi = heart; pariet = wall; visceralis = internal; serous/serum = whey
The heart wall
3 layers: epicardium, myocardium, and endocardium
* Epicardium (epi = upon, cardi = heart)
* = visceral layer of serous pericardium
* Serous membrane covering heart
Sonolary bamd espith erum tver vin thin layer of lose CT
* Myocardium (myo = muscle)
* Cardiac muscle
* Muscle spirals around heart which produces wringing motion.
* Fibrous skeleton of the heart
* Framework of collagen and elastic fibers
* Provides structural support and attachment for cardiac muscle & valves
* Electrical insulation between atria and ventricles
* Endo cardium lene inint orlart and blood vessels
* Simple squamous epithelium overlying thin layer of loose CT
The heart wall photo
Cardiac muscle
Cardiomyocytes: striated, short, thick, branched cells, one central nucleus
Intercalated discs: join cardiomyocytes end to end with three features:
* Interdigitating folds: folds interlock with each other, and increase surface area of contact
* Desmosomes: Mechanical junctions tightly join cardiomyocytes
* Gap junctions: Electrical junctions allow ions to flow between cells.
DIG
Intercalated discs
: Contractions of the heart originate within muscle cels themselves (myogenic
Contractions are triggered by pacemaker cells in the sinoatrial node and atrioventricular node
Electrical signal is transmitted by a nerve-like conduction pathway in the myocardium
Cardiac muscle cells contract on their own but are regulated by autonomic nervous system
Conduction system
- Sinoatrial node (Pacemaker): modified cardiomyocytes
* In right atrium near base of superior vena cava
initates each heartbeat and determins heart beat
- Excitation spreads through atrial myocardium
- Atrioventricular (AV) node:
Near the right AV valve
Electrical gateway to the ventricles
Excitation spreads down to:
Atrioventricular
4. Atrioventricular (AV) bundle (Bundle of His): bundle
into right and left bundle branches
branches pass though interventricular septum towards apex
- Subendocardial conducting network (Purkinje fibers): nerve like processes distribute excitation through ventricular myocardium.
Cardiomyocytes: then pass signal from cell to cell via gap junctions.
Entire myocardium of two atria or two ventricles acts like single, unified cell.
Fibrous skeleton: insulator prevents currents from getting to ventricles by any other route.
Heart rate in adult (at rest): 70 to 80 bpm (vagal tone).
Cardiac cycle
Cardiac cycle
The Blood Vessel Wall
arteries
Capillaries
Veins
Venous Return
Pulmonary Circuit
Branches of the Abdominal Aorta
Circulatory Pathways
Branches of thoracic aorta
Major Systemic Veins
Blood
Erythrocytes
Homeostasis:
Blood pressure
Heart rate
Arterial Sense Organs
