Lecture 14 - Cardiovascular System Flashcards
What are the characteristics/ functions of the heart
- > two side-by-side pumps that work at the same rate and pump the same volume of blood
- > blood flow within the heart os unidirectional because of four valves within the heart
- > generates BP through alternative cycles of the heart wall’s contraction (systole) and relaxation (diastole)
What is blood pressure
- > the force of the blood pushing against the inside wall of blood vessels
- > a minimum BP is essential to circulate blood throughout the body
Arteries vs Veins
Arteries
- > carries oxygenated blood from the lungs to the heart, to the rest of the body/body tissues
Veins
- > transport deoxygenated blood from capillaries/rest of body to the heart and then to the lungs
Capillaries
blood vessels involved in gas exchange between oxygenated & deoxygenated blood
Pulmonary vs Systemic circulation
Pulmonary
- > right side of the heart and the pulmonary arteries and veins; convey blood to the lungs for oxygenation and back to the left side of the heart
Systemic
- > left side of the heart and arteries and arteries and veins; conveys oxygenated blood to the body tissues and deoxygenated blood back to the right side of the heart
Which structures contribute to pulmonary circulation vs systemic circulation
Position of the heart within the mediastinum
Explain what the pericardium is and what is does
- > a tough sac that encloses the heart
- > restricts heart movements
The pericardium is composed of what?
2 main parts
- Fibrous pericardium - > outter covering of dense connective tissue
- Serous pericardium - > thin, delicate, moist membrane which is composed of 2 pars
- 1 - Parietal Layer - > lines outter surface of serous pericardium (attaches directly uner the fibrous pericardium)
- 2 - Visceral layer (epicardium) - > covers the outer surface of the heart (small space between the parietal and visceral layers is called the pericardial cavity)
Anatomy of the heart wall; Explain each layer
*superficial to deep*
- Epicardium - > consists of the visceral layer of the serous pericardium and areolar connective tissue
- Mycardium - > cardiac muscls; thickest of the three layes
- Endocardium - > internal surface of the heart chambers and external surface of the heart valves
Explain the structure of a cardiac muscle
- > branched shape (Y-shape)
- > single, central nucleus
- > striated (actin and myosin fibres)
- > connected by intercalcated discs
- > functional syncitium (mass of cells that merge together and work together)
Explain the cardiac vortex
- > atrial muscles are arranged in a figure-8 patten around the smaller atria
- > ventricular muscles are wrapped around and between the large ventricles
- > this allows for the blood to actually move in a specific direction when the heart contracts (intead of just queezing the blood out and in)
External anatomy of the heart
Consists of ….
• 4 hollow chambers (artia & ventricles separated by coronary sulcus)
- > 2 smaller and superior atria (sing. atrium)
- > 2 larger, inferior ventricles
- The infro anterior borders of the atria form a muscular extension called the auricles
- anterior/posterior interventricular sulcus
- > runs between reigh/left ventricles and from the coronary sulcus to the apex (bottom tip) of the heart
What are the valves found within the heart
- Right atrioventricular (tricuspid)
- Pulmonary semilunar
- Left atrioventricular (bicuspid or mitral)
- Aortic Semilunar
What are the three veins that drain into the right atrium and explain the journey of the blood out the atrium
- Superior vena cava
- Inferior vena cava
- Coronary sinus
- > dexoygenated venous blood (delivered by the three structures above) flows from RA through the right artioventricular valve
- > the right at.vent. valve is forced closed when the right ventrivle begins to contract, preventing blood backflow into RA
General characteristics of the right ventricle
- > receives deox venous blood from R.Atrium
- > the inner wall of each ventricle displays large, irregular muscular ridges called trabeculae carneae
- > typically 3 mucles projections inside R.Vent called papillary muscles which are anchors for chordae tendonae
- > deoxy blood must pass through the conus arteriosus (smooth tube which leads/ directs blood to PSL Valve) and pulmonary semilunar valve before being sent to heart
What separates the right and left ventricles
the interventricular septum
chordae tendonae
- > thin strands of connective tissue (made up of collagen fibres) which are anchored by the papilary muscles
- > attaches to three cusps of the R.atrioventricular valve (tricuspid)
- > cusps are triangular flaps that hang down into the ventricle
- > chorade tendonae prevents the cusps from prolapsing into right atrium when r.ventricle contracts
Semilunar valves
- > 2 of them: pulmonary and aortic
- > located in the roof of the right and left ventricles
- > each valve is made up of 3 semilunar cusps
- > no chordae tendonae
- > when ventricle contracts, blood pushes cusps against arterial trunks
- > when ventricle relaxes, some blood flows back towards the ventricle as the valve closes
General characteristics of left atrium
- > oxygenated blood from lungs travels thru pulmonary veins to l.atrium
- > left atrium is separated from left venticle by left atrioventrical valve (AV valve or mitral valve)
- > this valve ony has 2 triangular cusps
- > this valve is forced shut when the left ventricle contracts (similar process to r.atrioventrical valve)
shapes of the valves of the heart
Why is the left ventricular wall 3x bigger than the right ventricular wall
- > the left ventricle has to pump blood to the entire body (except lungs) and therefore has to generate more force to send it a greater distance
What is the aorta
largest vessel in the body and has three regions: ascending aorta, aortic arch and decending aorta
What are the three main arterial branches of the aortic arch
- Briachiocephalic trunk (supplies blood to right head & R.upper limb)
- > splits into right common carotid (head) and right subclavian (R.upper limb) - Left common carotid (left head)
- Left subclavian (left upper limb)
- > the decending aorta supplies blood to the rest of the body (both limbs and viscera)
Auscultation
the action of listening to heart valve sounds
- > we don’t put the stethescope directly over the valve but a little bit down/upstream of it because sound travels differently through blood and tissues
Explain the cardiac conduction system
Explain coronary arteries
- > coronary arteries feed heart healthy blood
- > the right and left coronary arteries travel within the coronary sulcus and supply heart wall muscle with healthy blood
- > small branches off the ascending, just above the aortic semilunar valve
Explain coronary veins
venous return of blood from the heart wall muscle occurs through three major veins
- Great Cardiac Vein - > runs alongside the anterior interventricular artery
- Middle cardiac vein - > runs alongside the posterior interventricular artery
- small cardiac vein - > travels close to the marginal artery
*all three drain into coronary sinus; that drains into R.Atrisum*
what are the only structures that go againts the vein = deox blood; artery = oxygenated blood
Pulmonary Artery - > only artery that carries deoxygenated blood
Pulmonary Vein - > only vein that carries oxygenated blood
Anatomy of blood vessels
- > the three classes of blood vessels are arteries, capillaries and veins
- > Arteries carry blood away from the heart and becme progressively smaller as they branch into artierions and finaly result into capillaries
- > veins return blood to heart and become progressively larger as they exit capillaries and merge into venules and veins
Explain blood vessel tunics
both artery and vein walls have three layers called (from outter to inner)
- > tunica externa (adventitia)
- > tunica media
- > tunica intima
*arteries have smaller lumen and tunica externa, bigger tunica media*
*veins have bigger lumen and turnica externa, smaller turnica media*
Function of tunica externa
*adventitia*
TE is conective tissue that helps anchor the blood vessel to an organ; larger blood vessels require their own blood supply; smaller arteries that supply the larger arteries are called vasa vasorum
Function of Tunica media
comprised of circularly arranged smooth muscle; sympathetic input causes the smooth muscle to contact, resulting in vasocontriction; parasympathetic input results in vasodilation
Functions of tunica intima
*interna*
composed of an endothelium (simple squamous epithelium lining the inside of the arteries and veins) and a subendothelium layer of areolar connective tissue
Types of arteries
- Elastic arteries
- Muscular arteries
- Arterioles
Elastic arteries
- > larges of the three types of arteries
- > the elastic fibres present in all three tunics allow these arteries to stretch under the increased pressure generated by bloodflow from the heart
- > elastic arteries branch into muscular arteries
Muscular arteries
- > medium diameter arteries
- > posess elastic fibres in two concentric rings between the three tunics:
1. Internal elastic lamina (IEL) which separates the tunica intima and tunica media
2. External elastic lamina (EEL) which separates the tunica media and tunica externa
Arterioles
- > smallest arteries; have less than 6 layers of smooth muscle in their tunica media
- > sympathetic innervation to the muscle fiber cells of the tunica media causes vasoconstriction resulting in elevation of BP
- > parasympathetic innervation causes vasodilation and a lowering BP
capillaries
- > smallest of all blood vessels
- > diametre only slightly larger than erythrocyte
- > wall consists solely of the tunica intima (a single layer of endothelial cells)
- > only type of blood vessel where metabolic exchange can occur between blood and cells outside of bloodstream
Types of capillaries
- Continuous - > most common type; endothelial cells form a contiuous and complete lining (no holes) aided by the presence of tight junctions
- Fenestrated - > endothelial cells that have small “holes” to allow fluid exchange between blood and interstitial fluid
- Sinusoid - > have big gaps between endothelial cells that promotes transport of larger molecules and cells to and from blood (how dying RBC leave blood stream to get recycled)
venules
- > smallest veins
- > companion vessels with arteioles
- > smallest ones are located at the distal end of a capillary bed and are called postcapillary venules
- > venules merge to form veins
veins
- > smaller and medium-sized veins travel with muscular arteries
- > larger veins travel with elastic arteries
- > BP in veins is too low to overcome gravity so they posess valves which prevent backflow (only lower have of body veins)
- > at rest the body’s veins hold 60% of the body’s blood; veins function as blood resevoir
skeletal muscle pump
the process in which the contraction of muscles also pumps blood towards the heart; this can help in bloods efforts to fight gravity
