Chapter 20 A & P FLASHCARD

20.1A: Major Functions of the Heart

• Pumping Blood: The heart ensures blood circulation throughout the body.

• Oxygenation of Blood: The right side pumps deoxygenated blood to the lungs.

• Delivery of Nutrients: The left side pumps oxygenated blood to tissues.

• Removal of Waste: Facilitates the removal of carbon dioxide and metabolic wastes.

• Maintains Blood Pressure: Ensures consistent blood flow by maintaining pressure.

20.2A: Size, Shape, and Location of the Heart

• Size: Approximately the size of a fist (about 250-350 grams).

• Shape: Cone-shaped, with a pointed apex directed downward.

• Location: In the thoracic cavity, between the lungs in the mediastinum, slightly left of the midline, behind the sternum, and above the diaphragm.

20.1A: Major Functions of the Heart

• Pumping Blood: The heart ensures blood circulation throughout the body.

• Oxygenation of Blood: The right side pumps deoxygenated blood to the lungs.

• Delivery of Nutrients: The left side pumps oxygenated blood to tissues.

• Removal of Waste: Facilitates the removal of carbon dioxide and metabolic wastes.

• Maintains Blood Pressure: Ensures consistent blood flow by maintaining pressure.

20.2A: Size, Shape, and Location of the Heart

• Size: Approximately the size of a fist (about 250-350 grams).

• Shape: Cone-shaped, with a pointed apex directed downward.

• Location: In the thoracic cavity, between the lungs in the mediastinum, slightly left of the midline, behind the sternum, and above the diaphragm.

20.2B: Importance of Knowing the Heart's Location

1. Medical Procedures: Crucial for CPR, defibrillation, and surgeries.

2. Diagnosis: Helps in interpreting symptoms like chest pain.

3. Injury Avoidance: Prevents harm during chest-related interventions.

20.3A: Structure of the Pericardium

Structure: A double-layered sac surrounding the heart.

• Fibrous Pericardium: Outer tough layer, anchors the heart.

• Serous Pericardium: Two layers (parietal and visceral) with pericardial fluid in between, reducing friction.

20.3B: Layers of the Heart Wall

• Epicardium: Outermost layer, provides protection and lubrication.

• Myocardium: Thick muscular middle layer, responsible for contraction.

• Endocardium: Inner layer lining the chambers and valves, minimizes resistance to blood flow.

20.3C: Large Veins and Arteries

• Veins Entering the Heart:

  • Superior and Inferior Vena Cava (to the right atrium).

  • Pulmonary Veins (to the left atrium).

• Arteries Exiting the Heart:

  • Pulmonary Arteries (from the right ventricle).

  • Aorta (from the left ventricle).

20.3D: Coronary Arteries

• Location: Originate from the base of the aorta.

• Blood Flow: Supply oxygenated blood to the myocardium.

20.3E: Cardiac Veins

• Location: Drain deoxygenated blood from the myocardium into the coronary sinus.

• Blood Flow: Return blood to the right atrium.

20.3F: Structure and Functions of Heart Chambers

• Atria: Receive blood (right from the body, left from the lungs).

• Ventricles: Pump blood (right to the lungs, left to the body).

20.3G: Heart Valves

• Atrioventricular (AV) Valves: Tricuspid (right) and Mitral (left); prevent backflow into atria.

• Semilunar Valves: Pulmonary and Aortic; prevent backflow into ventricles.

20.4A: Blood Flow Through the Heart

• Deoxygenated blood enters right atrium → tricuspid valve → right ventricle → pulmonary valve → lungs via pulmonary arteries.

• Oxygenated blood enters left atrium → mitral valve → left ventricle → aortic valve → body via aorta.

20.5A: Heart Skeleton

• Structure: Fibrous connective tissue framework.

• Functions:

  1. Electrical insulation.

  2. Support for valves.

  3. Attachment for cardiac muscles.

20.5B: Cardiac Muscle Cells

• Structural Features: Striated, branching, single nucleus, intercalated discs.

• Functions: Enable synchronized contractions.

20.5C: Cardiac vs. Skeletal Muscle

• Cardiac Muscle: Involuntary, intercalated discs, long refractory period.

• Skeletal Muscle: Voluntary, multinucleated, shorter refractory period.

20.5D: Conducting System

• Structure: Includes SA node, AV node, bundle of His, bundle branches, Purkinje fibers.

• Function: Coordinates contraction.

20.6A: Autorhythmicity and Pacemaker Potential

• Autorhythmicity: The heart generates its own electrical impulses.

• Pacemaker Potential: SA node's cells spontaneously depolarize.

20.6B: Action Potentials in Cardiac Muscle

Phases:

1. Depolarization (Na+ influx).

2. Plateau (Ca2+ influx).

3. Repolarization (K+ efflux).

Long Refractory Period

Importance: Prevents tetanus, ensures effective pumping.

20.6D: Electrocardiogram (ECG)

Waves:

• P wave: Atrial depolarization.

• QRS complex: Ventricular depolarization.

• T wave: Ventricular repolarization.

20.7A: Cardiac Cycle

• Phases:

  1. Atrial Systole.

  2. Ventricular Systole.

  3. Diastole.

• Relation to ECG: Aligns with waves and intervals.

20.7B: Heart Sounds

• Lub (S1): AV valves closing.

• Dub (S2): Semilunar valves closing.

20.8A: MAP, Cardiac Output, and Peripheral Resistance

1. MAP: Average blood pressure in arteries.

2. Cardiac Output (CO): Heart rate × stroke volume.

3. Peripheral Resistance: Resistance in blood vessels.

20.8B: MAP and Blood Flow

Role: Drives blood through systemic circulation.

20.9A: Intrinsic Regulation

Mechanism: Frank-Starling law; stroke volume increases with venous return.

20.9B: Extrinsic Regulation

1. Neural (sympathetic/parasympathetic).

2. Hormonal (epinephrine).

3. Ionotropic (external substances).

20.10A: Effects of Blood Chemistry

Changes in pH, CO2, O2 affect heart rate via chemoreceptors.

20.10B: Extracellular Ions

• High K+: Decreases heart rate.

• High Ca2+: Strengthens contractions.

20.10C: Temperature Effects

• High temperature: Increases heart rate.

• Low temperature: Decreases heart rate.

Anatomy and Physiology 2

A course focusing on the structure and functions of body systems, emphasizing interactions among systems to maintain homeostasis.