Human Physiology: Respiratory and Digestive Systems Overview

Internal Respiration

Exchange of O2 and CO2 between blood and tissues.

Dead Space

Part of respiratory system not involved in gas exchange.

Partial Pressure

Concentration of a specific gas in a mixture.

Blood pH Regulation

Maintains pH between 7.35 and 7.45.

Ventilation

Movement of air into and out of lungs.

Pulmonary Respiration

Exchange of gases between lungs and blood.

Systemic Respiration

Exchange of gases between blood and body cells.

Angiotensin-Converting Enzyme (ACE)

Regulates blood pressure in the body.

Upper Respiratory Tract

Includes external nose, nasal cavity, and pharynx.

Lower Respiratory Tract

Includes trachea, bronchi, and lungs.

Voice Production

Sound made as air moves through vocal cords.

Olfaction

Sensation of smell occurring in the nasal cavity.

Conducting Zone

Area with no gas exchange; air movement occurs.

Respiratory Zone

Area where gas exchange occurs in lungs.

Protection

Prevents microorganisms from entering respiratory system.

Inspiration

Air flows into lungs due to pressure drop.

Expiration

Air flows out of lungs due to pressure increase.

Gas Exchange Processes

Includes ventilation, external respiration, gas transport.

Boyle's Law

Volume and pressure are inversely proportional.

Diaphragm Function

Responsible for 2/3 of lung volume increase.

External Intercostal Muscles

Elevate ribs, increasing chest width and depth.

Alveolar Pressure

Pressure inside alveoli; influences air movement.

Thoracic Volume Changes

Increases during inspiration, decreases during expiration.

Diaphragm

Muscle that contracts for inhalation.

Quiet breathing

Passive process relying on lung elasticity.

Thoracic volume

Increases during diaphragm contraction.

Alveolar pressure

Decreases as alveolar volume increases.

External intercostals

Muscles that relax during quiet expiration.

Active Breathing

Forceful expiration using abdominal muscle contraction.

Alveolar Pressure

Pressure inside alveoli equal to atmospheric pressure.

Forced Vital Capacity

Functional measure of lung performance.

Spirometry

Process measuring air volumes in respiration.

Alveolar Ventilation

Volume of air available for gas exchange.

Spirometer

Device measuring pulmonary volume per minute.

Tidal Volume (TV)

Air volume inspired and expired during quiet breathing.

Dead Space

Area where no gas exchange occurs.

Inspiratory Reserve Volume (IRV)

Air that can be forcefully inspired after normal inspiration.

Expiratory Reserve Volume (ERV)

Air that can be forcefully expired after normal inspiration.

Residual Volume (RV)

Air remaining in lungs after maximal expiration.

Anatomical Dead Space

Upper and lower respiratory tract structures without gas exchange.

Physiological Dead Space

Combination of anatomical dead space and poorly exchanging alveoli.

Pulmonary Capacities

Sum of two or more pulmonary volumes.

Inspiratory Capacity

Maximal air inspired after normal expiration.

Functional Residual Capacity (FRC)

Air remaining in lungs after normal expiration.

Vital Capacity

Max volume expelled after maximum inspiration.

Total Lung Capacity

Sum of all lung volumes.

Lung Recoil

Lungs' tendency to decrease in size after stretching.

Partial Pressure (P)

Pressure exerted by a specific gas in a mixture.

Surfactant

Lipoprotein mixture reducing alveolar surface tension.

Pleural Pressure

Pressure in pleural cavity, less than alveolar pressure.

Gas Diffusion Factors

Conditions affecting oxygen diffusion across respiratory membrane.

Partial Pressure Gradient

Gas moves from high to low pressure.

Respiratory Membrane Thickness

Thicker membranes reduce gas diffusion rate.

Respiratory Membrane Surface Area

Larger area increases gas diffusion rate.

Pleural Space

Contains fluid that maintains pleura attachment.

O2 Diffusion

O2 moves from alveoli to blood.

CO2 Diffusion

CO2 moves from blood to alveoli.

Pulmonary Edema

Thickening of membrane decreases gas exchange.

Emphysema

Enlarged air sacs reduce surface area.

O2 Transport in Blood

98.5% O2 binds to hemoglobin.

CO2 Transport in Blood

CO2 interacts with blood components for solubility.

Carbonic Anhydrase

Enzyme converting CO2 and H2O to carbonic acid.

H2CO3

Carbonic acid formed from CO2 and water.

H+ Ion Production

Increased H+ lowers blood pH.

Hemoglobin Structure

Complex protein with 4 iron-containing heme groups.

O2 Affinity

Hemoglobin's affinity for O2 increases with binding.

CO2 Effect on Hemoglobin

CO2 binding decreases hemoglobin's O2 affinity.

Alveolar PO2

Partial pressure of O2 in alveoli.

Capillary PO2

Partial pressure of O2 in pulmonary capillaries.

Tissue PO2

Partial pressure of O2 in body tissues.

Alveolar PCO2

Partial pressure of CO2 in alveoli.

Capillary PCO2

Partial pressure of CO2 in pulmonary capillaries.

Tissue PCO2

Partial pressure of CO2 in body tissues.

Gas Exchange Process

O2 and CO2 exchange between blood and tissues.

Carbonic Anhydrase

Enzyme speeding up CO₂ and H₂O reaction.

Carbonic Acid

Formed from CO₂ and water in blood.

Bicarbonate Ion

HCO₃⁻, product of carbonic acid breakdown.

Hydrogen Ion

H⁺, released during carbonic acid dissociation.

Chloride Shift

Exchange of bicarbonate and chloride ions in blood.

Bohr Effect

H⁺ ions enhance oxygen release from hemoglobin.

Haldane Effect

Deoxygenated hemoglobin carries more CO₂.

Oxygen Release

Hemoglobin releases O₂ to tissues from blood.

CO₂ Transport Methods

CO₂ transported as dissolved gas, bicarbonate, or bound.

Dissolved CO₂

7% of CO₂ is directly dissolved in plasma.

Hemoglobin Binding

23% of CO₂ binds to hemoglobin in red blood cells.

Bicarbonate Transport

70% of CO₂ is transported as bicarbonate ions.

Respiratory Rate Regulation

Maintains blood gas concentrations within normal limits.

Sensitivity to CO₂

Body reacts to changes in CO₂ and blood pH.

Neurons in Brainstem

Control respiration; sensitive to blood gas levels.

CO₂ Exhalation

CO₂ moves from blood to alveoli for exhalation.

Reversal of Reaction

Bicarbonate and H⁺ convert back to carbonic acid.

O₂ Uptake

O₂ enters red blood cells from the lungs.

Alveoli Function

Site where CO₂ is exhaled and O₂ absorbed.

Carbonic Acid-Bicarbonate Buffer

Regulates blood pH by balancing CO₂ and bicarbonate.

Blood pH Regulation

Maintained through carbonic acid-bicarbonate buffer system.

Hemoglobin

Protein that binds oxygen in red blood cells.

Haldane Effect

Oxygen binding enhances CO₂ release from hemoglobin.

Bohr Effect

H⁺ release improves hemoglobin's oxygen binding.

Medullary Respiratory Center

Neurons controlling basic respiratory rhythm.

Dorsal Respiratory Group

Neurons primarily responsible for inspiration.