Exam 3 Notes on Circulatory and Respiratory Systems

PSA Formatting and Assignment Completion

• Importance of knowing the components of assignments and expectations.
• Assignment confusion can lead to excessive revisions.
• Need for clarity in course topics (e.g., internal transportation).

Examination Structure

• No final exam in certain classes; instead, multiple exams (six in total).
• Quizzes in physiology classes are considered straightforward.
• Lack of feedback can cause anxiety around grades.

Exam Preparation Tips

• Address questions about previous exams (e.g., Exam 2) to eliminate confusion.
• Importance of attending class and staying engaged with learning material.
• Take notes on objectives and highlighted concepts from lectures.

Circulatory System Overview

• Heart Valves: Discussed the function of cuspid (atrio-ventricular) and semilunar valves.

  • The role of cordae tendineae in valve positioning, not closure.
  • Semilunar valves prevent backflow during relaxation.

• Circulation Issues: Understanding ischemia and heart health.

  • Identify viable collateral circulation to sustain blood flow.
  • New muscle cannot replace dead heart muscle; leads to scar tissue.

Utero Heart Functionality

• Overview of fetal circulation and how it bypasses the pulmonary circuit using specific openings.
  • Ductus arteriosus: Closes after birth; turns into a ligament.
  • Foramen ovale: Closes to separate atrial blood flow post-birth.

Cardiac Muscle Structure

• Cardiac muscle is striated and branched, with unique intercalated discs for synchronization and contraction strength.
  • The mechanism of contraction: allowing heart rhythm to function efficiently.

Conductive Pathway of the Heart

• SA Node: Located in the right atrium; initiates electrical impulses at 60-100 beats per minute.
• AV Node: Delays signal from atria to ventricles to synchronize contractions.
• Bundle of His and Purkinje Fibers: Distribute the impulse through ventricles; they play a crucial role in heart contraction rhythm.

Electrocardiogram (ECG) Overview

• Understand the sections (P wave, QRS complex, T wave) related to electrical activity and contractions of the heart.
  • Atrial contraction occurs just before QRS wave is displayed.

Muscle Action Potential in Cardiac Muscle

• Cardiac action potentials are longer than in skeletal muscle to prevent rapid re-excitation, allowing for proper heart filling and pumping.
  • Calcium's Role: Vital for sustaining contractions in cardiac muscle during plateau phase.

Nervous System's Role in Heart Function

• Sympathetic Stimulation: Increases heart rate via norepinephrine and calcium influx.
• Parasympathetic Stimulation: Reduces heart rate through acetylcholine's effects, facilitating potassium influx to lower membrane potential.

Cardiac Output Calculation

• Product of stroke volume (~70 mL) and heart rate (~72 bpm) yields normal cardiac output (~5 L/min).

Heart Sounds

• Heart sounds correlate to the closure of heart valves; AV valves close at the beginning of ventricular contraction, semilunar valves close at the end of ventricular contraction.

Blood Pressure Influences

• Pressure = Flow / Resistance: Volume and friction within the vessel both affect overall blood pressure.
• Resistance influenced by vessel length, diameter, blood viscosity.

Summary: Flow vs. Velocity

• Flow refers to the amount of blood (volume), while velocity is the speed at which blood is traveling.
• Understand differentiation for application in circulatory system function and blood transport.

Capillary Exchange

• Importance of surface area and slow velocity for nutrient and gas exchange in tissues.
• Fluid dynamics analogy with garden hose to illustrate pressure drop over distance and increasing efficiency of blood circulation.

Homework and Next Topics

• Review connection of conductance system to heart function for upcoming exams.
• Prepare for discussions on respiratory systems and gas exchange mechanics for the next lesson.