Heart (Bio30S)

• Blood pressure is the force of blood pushing on artery walls.
• Blood pressure is the highest at the start of the vessel and lowest at the end.
• The normal range for blood pressure is 110-130/70-90 mmHg.
• Blood pressure is measured with a sphygmomanometer.
• Hypertension starts at 140/90 mmHg.
• Low blood pressure can cause dizziness or fainting.
• Factors that affect blood pressure.

  • Artery elasticity
  • Artery diameter
  • Blood viscosity
  • Heart rate
  • Blood volume
• Hypertension Homeostasis:

  • 130/90 mmHg
  • Stress -> BP rises
  • Baroreceptors in arteries
  • Medula Oblongata
  • Smooth muscle in arteries
  • Artery smooth muscle relaxes
• The relaxed phase of the cardiac cycle is diastole. The heart contracting is systole.
• Ventricles are thicker than atria because they need to pump blood out of the heart.
• During ventricular contraction, the AV valves close to prevent backflow into the atria.
• Semilunar valves close during diastole.
• The SA (Sinoatrial) Node at the top of the Right Atrium is the pacemaker, and generates an electrical current. The electricity travels through the atrial wall causing cardiac muscle to contract.
• At the bottom of the atria, the current transmits to the AV (Atrioventricular) node. The electrical current passes trhough the ventricle walls through Purkinje Fibers.
• The right side of the heart is deoxygenated.
• Parts of a heartbeat:

  1. P wave: Atrial contraction
  2. QRS complex: Ventricular contraction
  3. T wave, U wave: Diastole, ventricular relaxation
• ECG stands for electrocardiogram.
• Erratic heartbeat (Fibrillation) is treated with defibrillation.

  Defibrillators are devices that apply an electric shock to the heart.

  • They disrupt the electrical current (stopping) and give the SA node an opportunity to restart in a proper rhythm.
• Lub-dup sounds of the heart:

  The atria contract (LUB) pumping blood into ventricles.

  The ventricles contract (DUP) pumping blood into the lungs and body.
• The Cardiac Cycle:

  Atrial-Ventricular diastoly:

  • Heart chambers are relaxed and fill passively.
  • AV valves opened, semilunar closed.

  Atrial systoly:

  • Atria contract, forcing blood into ventricles.

  Ventricle systoly:

  • Ventricles contract.
  • AV valves closed, semilunar valves opened.
  • Blood enters pulmonary arteries and the aorta.
• Heart Attack

  Warning signs:

  • Increased heart rate
  • Indigestion
  • Left arm pain
  • Chest pain
  • Shortness of breath
  • Dizziness
  • Back pain, fatigue (female)
• Heart attacks are caused by a blockage in coronary arteries.(e.g. due to a clot)

  Heart cells are deprived of oxygen and die.
• Heart attacks are treated with tPa (tissue plasminogen) which unclot blood vessels. Defibrillators are used if the heart fibrillates.
• Heart Attack Prognosis:

  • Medicated with blood thinners.
  • Plaque rupture will heal.
  • Heart cells will not recover if affected.
• The left side of the heart is thicker because it pumps blood to the rest of the body.
• Right side:

  • Inferior+Superior Vena Cava
  • Right Atrium
  • (Tricuspid Valve)
  • Right Ventricle
  • (Pulmonary Valve)
  • Pulmonary Artery
• Left side:

  • Pulmonary Veins
  • Left Atrium
  • (Biscuspid / Mitral Valve)
  • Left Ventricle
  • (Aortic valve)
  • Aorta
• The muscle that separates the two sides of the heart is the septum.
• The tip of the heart is the apex.
• Pulse is the alternating expansion and relaxation of the artery wall.
• Blood pressure affected examples

  • Salt: Promotes water retention, increases blood volume
  • Stress: Hormones cause blood vessel contraction.
• Atherosclerosis:

  • Plaque buildup caused by fats in bloodstream
  • Thickening/hardening of artery wall
  • Ruptures cause blood clotting, heart attack, stroke
• Clogged blood vessels can be widened with angioplasty.
• Valve fibers (Chordae Tendineae) close and open valves in the heart
• Protective membrane surrounding heart

  • Pericardium