Structure and function, Lungs - Structure and function Flashcards
What are the four chambers of the heart?
Right Atrium
Right Ventricle
Left Atrium
Left Ventricle
What are the main layers of the heart wall?
Epicardium (outer layer): Protective outer covering.
Myocardium (middle layer): Contains cardiac muscle tissue.
Endocardium (inner layer): Lines the heart chambers and valves.
What is the pathway of blood through the heart?
Deoxygenated blood enters the right atrium from the vena cava.
Blood flows to the right ventricle and is pumped to the lungs via the pulmonary arteries.
Oxygenated blood returns to the left atrium via pulmonary veins.
Blood flows to the left ventricle and is pumped to the body via the aorta.
What are the properties of cardiac muscle?
Involuntary: Self-excitable, contracts rhythmically.
Intercalated Discs: Allow synchronized contraction.
Auto rhythmic Fibres: Generate action potentials independently
What are the phases of cardiac muscle contraction?
Depolarization: Na+ influx triggers rapid depolarization.
Plateau Phase: Ca++ enters, balancing Na+ outflow.
Repolarization: Ca++ channels close, K+ exits to restore resting potential.
What is the cardiac cycle?
Atrial Systole: Atria contract, filling ventricles.
Ventricular Systole: Ventricles contract, ejecting blood.
Diastole: All chambers relax, ventricles fill passively.
What is cardiac output (CO), and how is it calculated?
Cardiac Output: The volume of blood pumped per minute.
Formula: CO = Stroke Volume (SV) × Heart Rate (HR).
Example: 70 mL × 75 bpm = 5250 mL/min (5.25 L/min).
What are the three factors that govern stroke volume (SV)?
Preload: Stretch of cardiac muscle before contraction.
Contractility: Strength of contraction at a given preload.
Afterload: Pressure in blood vessels that ventricles must overcome.
What is the blood supply to the heart?
Coronary Arteries: Right coronary, left coronary, left anterior descending (LAD), and left circumflex arteries.
What is the role of the SA node in cardiac contraction?
SA Node (Sinoatrial Node): The pacemaker of the heart, initiates electrical impulses at 70-75 beats per minute.
What is the significance of the refractory period in cardiac muscle?
Prevents immediate re-stimulation of cardiac fibres, ensuring proper relaxation and effective pumping action.
What is the Frank-Starling law of the heart?
The more the heart is filled (stretched) during diastole, the greater the force of contraction during systole.
What are the gross structures of the lungs?
Right lung: 3 lobes (upper, middle, lower), separated by horizontal and oblique fissures.
Left lung: 2 lobes (upper, lower), separated by an oblique fissure.
Surrounded by pleura (visceral and parietal).
What are the main functions of the lungs?
Gaseous exchange.
Surfactant production.
Reservoir for blood.
Filtration of small clots and air bubbles.
Immune defense.
pH balance.
What are the components of the respiratory system?
Lungs.
Conducting airways.
Central nervous system.
Chest wall.
Muscles of respiration.
What structures are part of the upper respiratory tract?
Nose.
Mouth.
Pharynx (throat).
Larynx (voice box).
What are the parts of the lower respiratory tract?
Trachea.
Primary, secondary, and tertiary bronchi.
Bronchioles and terminal bronchioles.
Respiratory bronchioles, alveolar ducts, and alveolar sacs.
What is the difference between the conducting and respiratory zones?
Conducting Zone: From trachea to terminal bronchioles; no gas exchange occurs.
Respiratory Zone: From respiratory bronchioles to alveoli; gas exchange occurs at the alveolar-capillary membrane.
What are alveoli, and why are they important?
Alveoli are the sites of gas exchange in the lungs.
They have surfactant to reduce surface tension and collateral channels for air redistribution.
What is lung compliance?
Compliance refers to the lungs’ ability to expand.
Formula: Compliance = Change in volume / Change in pressure.
Reduced compliance is seen in conditions like atelectasis, fibrosis, pneumothorax, and obesity.
What factors determine airway resistance?
Lung volume.
Contraction of bronchial smooth muscle.
Airway obstructions.
Type of airflow (laminar, turbulent, or transitional).
What is elastic resistance?
Elastic resistance is the work required to expand the lungs during inhalation.
Elastic recoil is the lungs’ ability to return to their original shape after being stretched.
What is the role of the diaphragm in respiration?
A dome-shaped muscle that flattens during contraction to increase thoracic volume, aiding in inhalation.
Relaxes to dome shape during exhalation.
What are the airflow patterns in the respiratory system?
Laminar Flow: Seen in small airways.
Turbulent Flow: Seen in larger airways like the trachea, especially during high velocity.
Transitional Flow: A mix of laminar and turbulent, found in medium-sized airways.
What are common pathologies of the lower respiratory tract?
Trachea: Obstruction or floppy cartilage.
Bronchi: Obstruction or infection (e.g., bronchitis).
Bronchioles: Asthma, COPD, or fibrosis.
Alveoli: Affected by conditions like pneumonia and cystic fibrosis.
