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CVS, blood pressure, CVS conducting system, Electrocardiogram, CVS…

- - - - that is why the heart work as a one unite except for?
        
        the atrium and ventricle, they do not have gap junctions that's why they do not contract together
- - - - apex
        
        directed anteriorly, inferiorly to the left of the midclavicular line (5th intercostal space)
      - base
        
        directed posteriorly, superiorly to the right of the midclavicular line
    - - epicardium
        
        the most outer layer (the visceral pericardium)
      - myocardium
        
        the middle muscle layer (the thickest one)
      - endocardium
        
        inner endothelium lining
        
        epithelial smooth lining to allow easy movement and maintaining the integrity of the RBCs
    - - fibrous pericardium (superficial)
      - serous pericardium (inner)
        
        parietal pericardium (lines the interior of the
        fibrous pericardium).
        
        visceral pericardium (epicardium)
    - - intercalated discs: communication between to adjacent cells
    - - ventricles
        
        right ventricle
        
        form most of the anterior surface of the heart
        
        left ventricle
        
        thicker than the right ventricle
        
        form the apex of the heart
        
        why its thicker?
        
        cuz it pump the blood the whole body so it works in higher resistance
        
        the 2 ventricles are separated by an interventricular septum
        
        the anterior wall of the both atrium is rough because of the trabeculae carinae
      - atria
        
        left atrium
        
        receives blood from the 4 pulmonary veins
        
        right atrium
        
        receives blood from the superior and inferior vena cava and the coronary sinus
        
        between the left and right atrium there is interatrial septum
        
        contains a depression called (fossa ovalis)
        
        the anterior wall of the both atrium is rough because of the pectinate muscles
    - - when the heart contract they contract to pulling the valves (they are connected to valves) so they prevent the blood from coming back)
    - - keep blood moving through the heart in the right direction (the blood will never goes back from the ventricle to the atrium)
      - pulmonary valve
        
        Located between the right ventricle and the pulmonary artery.
      - aortic valve
      - bicuspid valve (mitral valve)
        
        between the left atrium and the left ventricle (2 flaps)
      - tricuspid valve
        
        Located between the right atrium and the right ventricle. (3 flaps)
      - flaps attached to white cords called chordae tendinea and connected to the papillary muscles
      - semilunar valve
        
        pulmonary SV
        
        allow blood to pass to pulmonary artery from the right ventricle
        
        aortic Sv
        
        allow blood to pass to the aorta from the left ventricle
    - - connect the valves together
      - provide insertion point for the muscles of the atria and ventricle (more mascular suppor0
      - work as an insulator (preventing the atria and ventricle from contracting at the same time)
  - - - tunica externa
        
        collagen fibers
      - tunica media
        
        smooth muscles
        
        elastic fibers
        
        the muscular layer
      - tunica intima
        
        endothlium
        
        loose C.T
    - - have thick wall (withstand high pressure)
      - layers
        
        tunic intima: thin inner epithelium
        
        tunica media: thick smooth muscle layer
        
        in large arteries: more elastic tissues with less smooth muscles
        
        tunica externa: outer C.T
      - 3 sizes
        
        large arteries
        
        elastic artery: their tunica media contain many elastic fibers and less smooth muscles
        
        medium artery
        
        muscular artery: have lesser elastic fibers and more SM
        
        small arteries
        
        arteriole: almost only smooth muscles
        
        the main artery that regulate the blood pressure
    - - microscopic vessels between arterioles and venues
      - made only of one layer (epithelial tissue)
      - form beds of vessels
        
        where the exchanging of substances between blood tissue
        
        precapillary sphincter that control the blood flow
      - capillaries types
        
        continuous capillaries
        
        the most dominants type and the least leaking
        
        found in the CNS, lungs, muscles, skin
        
        the one found in the brain is called blood-brain barrier (limit the ability of toxins to inter the brain)
        
        fenestrated capillaries
        
        has many openings, more leaky
        
        found in the kidneys, villi of small intestine, choroid plexus of the ventricles in the brain, ciliary processes of the eye and most endocrine glands
        
        sinusoids
        
        more bigger openings which are important for the blood cells to get into the circulation (the most leaky)
        
        found in the bone marrow, spleen, anterior pituitary, parathyroid, adrenal glands.
    - - return blood at low pressure to the heart
        
        therefore, less muscle and elastic tissue
      - have 3 layers but they are thinner than arteries
        
        have thicker tunica externa
      - venules
      - contain valves that carry blood against the gravity
      - vascular (venous) sinus
        
        like a vein but with bigger capacity and size and can take more blood
        
        has no smooth muscle
        
        it doesn't alter its diameter
        
        found in the brain: Dural venous sinuses
        
        also found in the heart: coronary sinus
- - - - anterior: sternum
      - posterior: thoracic vertebrae
      - lateral: right and left plural cavities
    - - anterior
      - middle
        
        where the heart is located
      - posterior
    - - divide the mediastinum to superior and inferior
- - - - HR X SV
  - - - vascular diameter
      - blood viscosity.
- - - - examples are:
        
        Epinephrine
        
        Nor Epinephrine
        
        Sympathetic Stimulation
        
        Calcium
        
        Caffeine
        
        Digitalis
        
        medicine
        
        Thyroxin
        
        hormone
        
        Glucagon
    - - examples are:
        
        Acetylcholine
        
        Parasympathetic stimulation
        
        Potassium
        
        Hypoxia
        
        low O2 amount
        
        Hypercapnia
        
        buildup of carbon dioxide in your bloodstream
        
        Acidosis
        
        Drugs Beta Blocker
        
        Myocardial infarction
- - - - Hormones
        
        Catecholamines
        
        Thyroid hormones
        
        Body temperature.
        
        Chemoreceptor's stimulation
        
        Emotions such as anger, anxiety,
        excitement.
        
        stress of physical exercise
        
        During inspiration
        
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  - - - drugs
        
        β-blockers,
        
        Ca++ channel blockers
        
        digoxin
        
        During Expiration
        
        Carotid Massage (baroreceptors stimulation)
        
        Massage of the eyeball
- - - - the afterload: how much is the resistance against the heart wall
        
        inverse relationship
        
        – Afterload on Left Ventricle > Afterload on Right Ventricle
        
        – Contractility of Left Ventricle > Contractility of Right Ventricle
        
        stroke volume is equal in both sides = cardiac output the same in both
        
        abnormalities of high resistance (reduced SV)
        
        Aortic valve stenosis
        
        Coarctation of aorta
        
        Systemic hypertension
    - - venous return: less VR less amount of blood reaches the ventricle
        
        increased venous return= increased cardiac output
        
        both increases in inspiration (respiratory pump)
        
        both increases during exercises (muscle pump)
        
        both increases during sympathetic stimulation ( venomotor tone)
        
        gravity: upright posture decreases VR
      - atrial systole: any disease makes the atria not contract reduce the blood in the ventricles (e.x atrial fibrillation)
      - duration of diastole: the longer diastole the filler the ventricles get
        
        usually the relation between the CO and the HR is proportional but to a certain limit ( when the heart rate gets too high the cardiac output decreases) why?
      - ventricular distensibility (capacity):small space = less blood in the ventricular
- - - - affecting the stroke volume, heart rate, and peripheral resistance
        
        what control this regulation
        
        cardiovascular center in the medulla oblingata
        
        autonomic nervous system
        (ANS)
        
        Hormones or chemicals
        
        Vasomotor center consists of groups of neurons situated in the Medulla oblongata
        responsible for maintaining the homeostasis within the cardiovascular system.
        
        ex: someone developed sever bleeding what will happen? he will bleed, therefore the blood pressure will go too low , the receptors in the major arteries will sense the sudden reduction in BP. therefore, they will innervate the vasomotor center as response the vasomotor center will increase the HR, the contractility and in the same time will stimulate the contractility of the blood vessels
        
        when the pressure is too high the opposite will happen, the signals will inhibit the HR etc
        
        hormones that work within the short term regulations are
        
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        what regulates the vasomotor center?
        
        efferent regulators
        
        Stimulated Cardiac vasomotor center (through sympathetic nerves) Causes
        
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        transmit the actions from the VC to directed organ
        
        afferent regulators
        
        Baroreceptors which are responsive to stretching send inhibitory stimuli to
        vasomotor Centre.
        
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        Chemoreceptors which are responsive to changes in oxygen and carbon-dioxide
        concentrations in the blood send stimulatory stimuli to vasomotor Centre.
        
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        detect changes and transmit it to the vasomotor center
  - - - The long-term regulation of blood pressure is mainly by controlling the
        amount of intravascular fluid thus increasing the blood volume.
        
        The increase in blood volume increases the venous return and thus it
        increase the stroke volume
        
        The long-term regulation also affects the peripheral resistance.
        
        The regulatory mechanisms are mostly hormonal.
        
        how it occurs?
        
        • When blood volume falls or blood flow to the kidneys decreases,
        
        juxtaglomerular cells in the kidneys secrete renin into the
        bloodstream
        
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        Antidiuretic hormone (ADH):
        
        produced by the hypothalamus and released from the posterior pituitary in response to dehydration or decreased blood volume
        
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        Atrial natriuretic peptide (ANP):
        
        • Released by cells in the atria of the heart
        
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- - - - when the pacemaker potential reach the threshold what happen?
        
        trigger AP
        
        that spread throughout the atria
        
        2 atria contarct
  - - - at the AV node the AP slows
        
        that gives time for the ventricles to be filled with blood before contracting (pump)
- - - - Late Diastole
        
        The mitral and tricuspid valves between the atria and ventricles are open
        
        Atria and ventricles are relaxed
        
        The aortic and pulmonary valves are
        closed.
        
        Blood flows into the heart throughout
        diastole, filling the atria and ventricles.
        
        The pressure in the ventricles remains low
        
        Atrial Systole
        
        contraction of the atria to fill the ventricles with additional blood but majority of it was already filled in the late diastole
        
        during contraction some regurgitation of blood into veins may happen
        
        Ventricular Systole (isovolumic contraction)
        
        The mitral and tricuspid (AV) valves close giving rise to
        the first heart sound.
        
        Ventricular muscle pressure rises sharply as the
        myocardium presses on the blood in the ventricle ( that's why its called isovolmic because the blood is trapped inside the ventricles so it remain constant)
        
        Ventricular contraction lasts until the pressures in the left and right ventricles exceed the pressures in the aorta (80 mm Hg) and pulmonary artery (10 mmHg).
        
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        Ventricular Ejection
        
        pressures in the left and right ventricles exceed the pressures in the aorta (80 mm Hg) and pulmonary artery (10 mmHg). the pulmonary and aortic valves will open
        
        ejection is fast at the beginning but slow down as systole progress
        
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        Early Diastole (Isovolumetric
        ventricular relaxation)
        
        ventricular pressures drop more rapidly.
        
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  - - - SV/EDV
        
        amount of blood pumped out of the ventricles/ total amount of the blood in ventricles
      - Normally is about 65%
      - valuable
        index of ventricular function.
- - - - therefore there must be a system to coordinate their contraction which is the conductive system
        
        the conductive fibers forming this system are called: Auto rhythmic conductive
        fibers
        
        they stimulate the heart to contract
        
        problems with these fibers result in abnormal heart beats (arrhythmias)
- - - - atria contract
        
        the impulses are delayed briefly in the AV
        
        impulses travel through the AV bundle branches and Purkinje fibers
        
        ventricles contract and the blood is ejected from the heart
- - - - The S–T segment is elevated (above the baseline) in acute myocardial infarction and depressed (below the baseline) when the
        heart muscle receives insufficient oxygen(ischemia).
  - - - Hear rate = 300/no. of large squares between 2 R waves
    - - Heart rate = No. of R waves within 15 large squares X 20
- - - - supply oxygenated blood to the wall of both ventricles
    - - distribute the oxygenated blood to the walls of the left ventricle and left atrium
  - - - supply oxygenated blood to the wall of both ventricles
    - - transport oxygenated blood to the wall of right ventricle
  - - - in the anterior interventricular sulcus
      - drains the heart areas supplied by the left coronary artery
    - - in the posterior interventricular sulcus
      - drains the areas supplied by the posterior interventricular branch of right coronary artery
    - - in the right atrium
    - - drain the right atrium and the right ventricle
    - - drain the right ventricle