Respiratory System anatomy and physiology

Respiratory System anatomy and physiology BS Nursing

1. Respiratory System Discuss the physiology of respiration by explaining the mechanism of  Pulmonary Ventilation  External Respiration  Internal Respiration Discuss nervous control of respiration Briefly discuss the lung volumes & capacities

2. Members Aleeza Ansar Areeba Atiq ur Rehman Ayesha Amin Ayesha Mumtaz Muhammad Awais Mushtaq

3. The physiology of respiration involves the process of breathing, which consists of two main components: pulmonary ventilation and gas exchange. Pulmonary ventilation is the mechanical process of moving air into and out of the lungs and is essential for bringing oxygen into the body and removing carbon dioxide. Pulmonary ventilation

4. Breathing Cycle:

5. Lung volume and capacity • Lung volumes and lung capacities refer to the volume of air associated with different phases of the respiratory cycle. • Lung volumes are directly measured; Lung capacities are inferred from lung volumes • Instrument is spirometry Lung Volumes • Four types 1. Tidal volume 2. Inspiratory reserve volume 3. Expiratory persevere volume 4. Residual volume

6. Tidal volume •The volume of the air inhaled/exhaled in a normal breathing TV = 500ml Inspiratory reserve volume • The additional amount of the air that can be inhaled with maximum effort after normal inspection IRV = 3000ml Expiratory Reserve Volume The additional amount of the air that can be exhale with maximum effort after normal expiration ERV = 1100

7. Inspiratory capacity • Maximum volume of air that can be inspired after normal tidal expiration IC = TV+IRV = 500 +3000 =3500 ml Expiratory Capacity • Maximum volume of air that can be expired after normal tidal inspiration EC=TV+ERV(500+1 100 = 1600ml ) Functional Residual Capacity • Volume of air remaining in lungs after normal tidal expiration FRC= ERV + RV (1100 + 1200 = 2300ml)

8. Volume of Air In Lungs

9. Lungs Volume And Capacities

10. Neural Control of Respiration : The brainstem, specifically the medulla oblongata and the pons, houses the respiratory centers that regulate the rhythm, rate, and depth of breathing. These centers control both voluntary and involuntary breathing. .

11. Neural Control of Respiration

12. Chemical Control The nervous system responds to changes in blood gases and pH levels via chemoreceptors: • Central Chemoreceptors (Medulla): Detect changes in carbon dioxide (CO₂) levels and pH in cerebrospinal fluid. • Peripheral Chemoreceptors (Carotid and Aortic Bodies): Monitor oxygen (O₂), carbon dioxide, and pH levels in the blood. When CO₂ levels rise (hypercapnia) or O₂ levels fall (hypoxia), these chemoreceptors signal the brainstem to adjust the respiratory rate and depth.

13. 5. Autonomic Nervous System: The autonomic nervous system (ANS) modulates respiratory functions: •Sympathetic Activation: Increases respiratory rate and bronchodilation. (e.g., during stress or exercise). •Parasympathetic Activation: Promotes normal, relaxed breathing and bronchoconstriction. This integrated system ensures breathing is both automatic and adaptable to the body’s metabolic needs.

14. Anatomy and physiology book of Ross and wellsons Reference

15. ANY QUESTIONS

16. Mechanism of Pulmonary Ventilation: Pulmonary ventilation occurs through two phases: inspiration (inhalation) and expiration (exhalation). The movement of air into and out of the lungs is driven by changes in pressure within the thoracic cavity relative to atmospheric pressure.

17. Inspiration (Inhalation): Diaphragm Contraction: The diaphragm contracts and moves downward, increasing the vertical volume of the thoracic cavity. External Intercostal Muscle Contraction: The external intercostal muscles between the ribs contract, lifting the rib cage upward and outward, expanding the chest cavity in the horizontal dimension. Lung Expansion: As the volume of the thoracic cavity increases, the lungs expand. According to Boyle's Law, when the volume of the thoracic cavity increases, the pressure inside the lungs (intrapulmonary pressure) decreases. Air Flow into Lungs: Because atmospheric pressure is higher than the intrapulmonary pressure, air flows into the lungs to equalize the pressure difference. This process continues until the pressures are equalized.

18. Expiration (Exhalation): Diaphragm and Intercostal Muscle Relaxation: During quiet breathing, expiration is largely a passive process. The diaphragm and external intercostal muscles relax, causing the thoracic cavity to decrease in volume. Elastic Recoil of the Lungs: The lungs, which have elastic properties, recoil to their resting state, compressing the air inside. Increased Pressure in the Lungs: As the volume of the thoracic cavity and lungs decreases, intrapulmonary pressure rises above atmospheric pressure. Air Flow Out of Lungs: The higher intrapulmonary pressure forces air out of the lungs to the atmosphere until the pressures are balanced again.

19. Factors Affecting Pulmonary Ventilation: Airway Resistance : Narrowed or obstructed airways (due to conditions like asthma) increase resistance to airflow, making ventilation more difficult. Lung Compliance : The ability of the lungs to stretch and expand; reduced compliance (due to diseases like pulmonary fibrosis) can make it harder for the lungs to inflate. Surface Tension : Surfactant in the lungs reduces surface tension within the alveoli, helping them to stay open and facilitating gas exchange. In summary, pulmonary ventilation is driven by pressure changes in the thoracic cavity that result from the actions of the diaphragm and intercostal muscles, ensuring that air is moved into and out of the lungs efficiently.

20. Residual Volume • THE VOLUME OF AIR REMAINING IN THE LUNGS AFTER MAXIMAL EXHALATION PREVENTING LUNGS FROM COLLAPSING RV = 1200 Lung capacities • These are combinations of two or more lung volumes 1.Inspiratory capacity 2. Expiratory capacity 3. Functional residual capacity 4. Vital capacity 5. Total lung capacity

21. Vital Capacity • Maximum Amount of air expelled after deepest possible inspiration VC = TV+IRV+ERV500+3000+1100=4600ml Total Lung Capacity • Volume of air present in lung after max inspiration TLC = VC + RV (4600+1200 = 5800ml)

22. Medullary Respiratory Center : The medulla oblongata contains the primary respiratory control centers: Dorsal Respiratory Group (DRG): The DRG is mainly responsible for controlling the basic rhythm of breathing by generating nerve impulses that stimulate the muscles involved in in inspiration. It sends signals to the the diaphragm and the external intercostal muscles to contract, leading to inhalation. Ventral Respiratory Group (VRG): The VRG is more active during forceful breathing, such as during exercise or stress. It controls both inspiration and expiration by activating additional respiratory muscles

23. Pons Respiratory Centers: The pons contains two regions that modify the activity of the medullary centers. Pneumotaxic Center: This center helps regulate the rate and pattern. of breathing by limiting the duration of inspiration. It works to prevent over-inflation of the lungs by sending inhibitory signals to the medullary respiratory centers. Apneustic Center : The apneustic center promotes prolonged inhalation by stimulating the medullary centers. It provides an excitatory effect on inspiration

24. 3. Voluntary Control: The cerebral cortex allows voluntary control over breathing (e.g., holding your breath or speaking). Signals from the cortex bypass the brainstem and directly influence respiratory muscles. 4. Reflex Mechanisms •Hering-Breuer Reflex: Stretch receptors in the lungs send inhibitory signals to the brainstem to prevent over-inflation of the lungs. •Irritant Reflexes: Irritant receptors in the airways trigger coughing or sneezing to expel harmful substances. •Proprioceptive Input: During physical activity, stretch receptors in muscles and joints signal the brain to increase breathing.