Unit 8 - Respiratory System

Basic Functions of Respiratory System

Breathing, Maintenance of Homeostasis, Sensory Information, Filters/Warms/Moistens air that enters the body, produces sounds

Conduction Zone

The part of the respiratory system that consists of the nostrils, mouth, trachea, primary, secondary, and tertiary bronchus, and bronchioles

Respiratory Zone

The part of the respiratory system that consists of the alveoli, alveolar ducts, and capillaries

Pleura

Thin, moist, slippery membrane around the lungs

Visceral Pleura

Pleura that covers the lungs

Parietal Pleura

Pleura that lines the thoracic cavity and the upper surface of the diaphragm

Pleural Fluid

Fills the space between the two pleural membranes; reduces friction

Pleurisy

Inflammation of the pleural membrane

Inhalation/Inspiration

Act of drawing air into the lungs. Diaphragm contracts, moves downward. Ribcage moves up and out; intercostal muscles contract. Pressure within thoracic cavity decreases as volume increases. Lungs expand due to decreased pressure.

Exhalation/Expiration

Act of expelling air from the lungs. Diaphragm relaxes/moves upward. Ribcage moves down and in; intercostal muscles relax. Pressure within thoracic cavity increases as volume decreases. Lungs squeezed and air forced out.

Ventilation

Inhalation/Exhalation; exchange of air between lungs and environment

Alveolus

Sac-like structure with single cell layer thick walls. Found in clusters at the end of alveolar ducts. Encases in a network of capillaries. Location of gas exchange between lungs and blood.

Surfactant

A lipid-like substance covering the inner surface of an alveolus which stabilizes it and prevents it from collapsing

Thickness of Membrane

Factor affecting gas exchange related to increased thickness results in decreased rate of gas exchange

Surface Area

Factor affecting gas exchange related to decrease in the inner area of lungs that results in a decrease in gas exchange

Gas Pressure Gradients

Factor affecting gas exchange related to correct pressures in order to exchange gas properly

External Respiration

Blood gains O₂ and loses CO₂ (exchange at respiratory membrane), exchange of gases between lungs (alveoli) and blood found in the pulmonary capillaries

Internal Respiration

Blood loses O₂ and gains CO₂, exchange of gases between systemic capillaries and tissue cells. Gases entering the blood dissolve in plasma or combine chemically with blood components (hemoglobin)

Oxyhemoglobin

Oxygenated form of hemoglobin, 98+% of O₂ is bound to hemoglobin in RBCs, only 1-2% dissolves in plasma

Hemoglobin

An iron containing molecule found in RBCs that binds to oxygen gas so that it can be transported in the bloodstream

Bicarbonate

Most common form of CO₂ in the blood, converted to carbonic acid then dissolved in blood, 70%. (7% stays intact in plasma)

Carbaminohemoglobin

CO₂ + Hemoglobin, 23% of all carbon dioxide in the blood, that occurs when carbon dioxide binds to hemoglobin, allowing for transport back to the lungs.

Release of Oxygen

P O₂ decreases (pressure gradient exists), blood concentration of CO₂ increases, blood becomes more acidic (decreased pH), and blood temperature increases

Aerobic Cellular Respiration

Biochemical process by which cells utilize O₂, and organic compounds to produce ATP necessary for cellular metabolism

Acidosis

A condition where the blood is too acidic (low pH)

Alkalosis

A condition where the blood is too alkaline (high pH)

Control Center

Part of the negative feedback mechanism that consists of the respiratory center

Effectors

Part of the negative feedback mechanism that consists of the intercostal muscles & diaphragm

Receptors

Part of the negative feedback mechanism that consists of the peripheral and central chemoreceptors

Stimulus

Part of the negative feedback mechanism that consists of the change in blood pH

Respiratory Center

Sets the basic rhythm of ventilation, found in medulla, regulates rate and depth of breathing

Central Chemoreceptors

Found in medulla; sensitive to change in pH in CSF

Peripheral Chemoreceptors

Receptors located in the wall of the aortic arch and in the walls of the carotid arteries, sensitive to changes in pH of blood plasma

Stretch Receptors

Found in the walls of bronchi and bronchioles; activated when the lungs expand to their physical limit. These receptors signal the respiratory center to discontinue stimulation of the inspiratory muscles

Phrenic Nerve

A motor nerve that innervates the diaphragm, playing a crucial role in breathing by stimulating contraction and relaxation during inhalation and exhalation.

Intercostal Nerves

Nerves stimulate the assistance with both inspiration and expiration. Inspiration →stimulates exterior intercostal muscles to contract, pulling the ribcage up and out. Exhalation → stimulates the internal intercostal muscles, which causes the ribcage to depress and shrink the chest cavity.

Vagus Nerve

A vital parasympathetic nerve that carries signals from the stretch receptors to the respiratory center in order to inhibit inhalation. It manages relaxed breathing and manages involuntary breathing. It also plays a role in airway diameter and respiratory rate.

Inflation Reflex

A protective reflex that prevents over-inflation of the lungs by triggering exhalation when the lungs stretch beyond a certain point. It involves the activation of stretch receptors in the lungs, which send signals to the brain to inhibit further inhalation.

Spirometry

The process of measuring volumes of air that move into and out of the respiratory system

Spirometer

A device used to measure pulmonary volumes and assist in diagnosing pulmonary disorders

Tidal Volume (TV)

Air inspired/expired during a normal breath

Inspiratory Reserve (IR)

Air that can be forcefully inspired after a normal inspiration

Expiratory Reserve (ER)

Air expelled forcefully after expiration of normal tidal volume

Residual Volume (RV)

Volume of air still remaining in lungs after a maximum expiration

Vital Capacity (VC)

IRV + TV + ERV. Maximum amount of air a person can expel after a maximum inspiration

Effects of Aging on Respiratory System

Alveoli, respiratory tract, and chest wall become more rigid and less elastic. Decreased lung capacity; reduced vital capacity. More susceptible to pulmonary disorders

Hypoxia

Insufficient O₂ for cellular respiration

Apnea

Absence of ventilatory movements

Dyspnea

Painful or labored breathing

Hyperventilation

Increased pulmonary ventilation in excess of metabolic needs, results in excessive intake of O₂ and increased elimination of CO₂ leading to disturbance of acid-base balance, causes dizziness, tingling in extremities, and may cause fainting

Hypoventilation

Pulmonary ventilation inadequate to meet metabolic needs, decreased levels of O₂ and increased levels of CO₂ in the blood, causes cyanosis, decreased ventilatory activity is associated with overdose of drugs and SIDS