BIOL 117 Exam 1 Study Guide

HEART

Structures of the heart

  1. Exterior
    1. Auricles: right and left atria
    2. Great vessels:
      1. Superior and Inferior Vena Cavae (drain deox blood into right atrium)
      2. Pulmonary Trunk (pumps deox blood from right ventricle to lungs)
      3. Pulmonary Veins (drain ox blood from lungs into left atrium)
      4. Aorta (pumps ox blood to body from left ventricle)
  2. Interior
    1. Chambers
      1. Right Atrium: receives deox blood from body
      2. Right Ventricle: receives deox blood from right atrium and pumps to lungs
      3. Left Atrium: receives ox blood from lungs
      4. Left Ventricle: receives ox blood from left atrium and pumps to body
    2. Valves
      1. Right Atrioventricular (AV) Valve: separates RA and RV; “bicuspid”
      2. Pulmonary Semilunar Valve: separates RV and pulmonary trunk
      3. Left AV Valve: separates LA and LV; “tricuspid” or “mitral”
      4. Aortic Semilunar Valve: separates LV and aorta
    3. Layers
      1. Endocardium: inner of heart and external of valves; simple squamous and areolar; lines vessels
      2. Myocardium: contracts for pump
      3. Epicardium: aka visceral pericardium; outer layer; simple squamous and areolar
    4. Fibrous skeleton: dense irregular CT; electrical insulator; so the atria and ventricles don't beat at the same time; attachment point for the valves to prevent backflow
    5. Cardiomyocyte: striated (has sarcomere), has intercalated discs (desmosomes and gap junctions) for cell communication; RMP = -90 mV

Route of cardiac conduction: Sinoatrial (SA) node → Atrioventricular (AV) node → AV bundle → right and left bundle branches → Purkinje fibers; nodal cell RMP=-60mV and threshold -40mV

ECG waves/intervals: P (atrial depolarization), QRS (atrial repolarization, ventricle depolarization), T (ventricular repolarization)

  1. Plateau phase: Ca2+ channels open and let ions in to maintain depolarization even with K+ channels open
  2. Ions going in and out: Na+ and Ca2+ going in and K+ going out

Cardiac cycle - phases

  1. Atrial Relaxation and Ventricular Filling
    1. 4 chambers at rest
    2. AV valves open
    3. passive ventricular filling
    4. Semilunar valve closed
  2. Atrial Contraction and Ventricular Filling
    1. SA node fires
    2. AV valves open
    3. ventricles filling untilEDV
    4. semilunar valves closed
  3. Isovolumetric Contraction
    1. AV valves closed
    2. semilunar valves closed
    3. ventricles contracting but not pumping blood away because ventricular pressure< arterial pressure
  4. Ventricular Ejection
    1. semilunar valves open
    2. ventricles pump blood into arteries bc ventricular pressure> arterial pressure
    3. AV valves closed
  5. Isovolumetric Relaxation
    1. AV valves closed
    2. semilunar valves closed
    3. 4 chambers at rest and blood is stagnant

Cardiac output: amount of blood pumped by 1 ventricle per min; L/min

  1. Formula: CO=HRxSV
  2. Stroke volume: amount of blood ejected in one heartbeat
  3. Factors affecting stroke volume:
    1. venous return (preload): determines preload; increased venous pressure and/or fill time (decreased HR) → increased SV
    2. inotropic agents: affect contractility
    3. afterload: resistance (pressure in arteries); increased afterload → decreased SV
  4. Chronotropic: pos (increases HR; EPI, NE, cocaine, nicotine, TH, caffeine) and neg (decreases HR; ACh)
  5. Inotropic: pos (increases SV; more Ca2+) and neg (decreases SV; less Ca2+)

BLOOD VESSELS

Differences between types of vessels

  1. Artery: away from heart; supplies; thick tunica media, narrow lumen, more elastic and collagen fibers; stays open w/o blood
    1. Elastic: bigger; closer to heart; lots of stretch and recoil (more elastic fiber)
    2. Muscular: middle size; vasoconstriction/dilation (thick tunica media)
    3. Arteriole: smallest; close to capillary
  2. Vein: towards heart; drains; thick tunica externa, wider lumen, less fibers; closed w/o blood
    1. Valves: prevent backflow
    2. Blood reservoir: hold a lot of blood for long time bc it doesn’t move very fast
  3. Capillary: gas exchange
    1. Continuous: most common; complete w tight junctions w intercellular clefts (borders) to allow small substances
    2. Fenestrated: complete w tight junctions and intercellular clefts + fenestrations (small pores) for small proteins
    3. Sinusoid: incomplete w large openings; more permeable
    4. Precapillary sphincter: open (flows through true capillaries), closed (bypass via thoroughfare channel)
    5. Capillary bed: web of capillaries working together
    6. Portal system: two capillary beds bc blood goes to second organ before going back to heart
    7. NFP (net filtration pressure): higher hydrostatic pressure on arterial end (go out of capillary) and higher osmotic pressure on venue end (go into capillary)
    8. Vasa Vasorum: vessels that supply blood to vessels
  4. Tunics
    1. tunica intima: endothelium (continuous w endocardium) and subendothelial layer (areolar CT)
    2. tunica media: smooth muscle and elastic fiber
    3. tunica externa: areolar CT; anchors vessels to other structures
  5. Differences in pressure in each: highest in arteries (about 120/80)—> capillaries(sys=dia)—> lowest in veins(0 by the times it reaches vena cava)

Angiogenesis: growing new vessels in tissues that need more perfusion; return to normal is called regression

Blood pressure regulation: blood volume, cardiac output, TPR

  1. Neural: in medulla oblongata; short term
    1. vasomotor center: regulates resistance through SNS only
    2. cardiac center: cardioacceleratory (increase HR&SV→ CO; SNS) and cardioinhibitory (decrease HR&SV→CO; PSNS) centers
  2. Hormonal: long term
    1. ANP (atrial natriuretic peptide): vasodilation → decrease resistance and increased urine output → decreased blood volume → decreased BP
    2. Renin/Angiotensin II: vasoconstriction → increased resistance→ increase BP; thirst center stimulation and decreased urine formation → increased blood volume → increased BP
    3. Aldosterone: from adrenal cortex; increased Na+ and water in kidney → blood volume maintenance→ increase BP
    4. ADH (antidiuretic hormone): from posterior pituitary; thirst, kidney water absorption → maintain bloo volume → increase BP
  3. Peripheral resistance: friction due to blood contact w vessel wall
    1. Blood viscosity: usually constant; thickness due to particles (WBC, RBC, platelets) and fluid (plasma); high viscosity→ high resistance
    2. Blood vessel length: constant besides angiogenesis; longer vessel → more resistance
    3. Vessel diameter: changes often; laminar flow says fluid moves faster in middle; vasodilation → less resistance and vasoconstriction → more resistance
  4. Afterload: increase AL→decrease SV→decrease CO→ decrease BP
  5. preload: increased PL→ high SV→higher CO→higher BP
  6. Baroreceptors: if BP decreases…
    1. decreased stretch detected by baroreceptors
    2. decreased signals to cardiovascular system
    3. cardioacceleratory center increases signals along SNS to SA node, AV node, and myocardium/ cardioinhibitory center decreases PSNS signals (increase CO)
    4. vasomotor SNS signals cause vasoconstriction (increase TPR)
    5. GOAL: increase BP
  7. chemoreceptors: if high CO2, low pH, or low O2
    1. chemoreceptors increase vasomotor signals
    2. vasoconstriction (increase TPR)
    3. venous reservoir blood moves to venous return (increase SV→CO)
    4. GOAL: increase BP
    5. better respiratory gas exchange :D

Measurements

  1. Arterial Blood Pressure: sys/dia
  2. Pulse pressure: sys-dia; measure arterial elasticity
  3. Mean Arterial Pressure: dia + ⅓(pulse pressure)

Routes of blood vessels

  1. Vessels coming off the heart
  2. Upper limb
  3. General route down to foot
  4. Pulmonary vs. systemic vs. umbilical
    1. Pulmonary: arteries carry deox blood and veins carry ox blood
    2. Systemic: arteries carry ox blood and veins carry deox blood
    3. Umbilical: arteries carry deox blood to placenta and veins carry ox blood from placenta; placenta works as the capillaries