Biology - Breathing and Exchange of Gases Flashcards

A comprehensive set of 200 vocabulary flashcards covering Human Physiology: Breathing and Exchange of Gases, as well as the biography of Alfonso Corti and introductory concepts of systems biology.

Reductionist approach

The study of life forms that resulted in increasing use of physico-chemical concepts and techniques, often using surviving tissue models or cell-free systems.

Systems biology

The belief that all living phenomena are emergent properties due to interaction among components of the system under study.

Molecular physiology

A field that became almost synonymous with biochemistry and biophysics.

Emergent properties

Properties created by the interaction of regulatory networks of molecules, supra molecular assemblies, cells, tissues, organisms, populations, and communities.

Alfonso Corti

An Italian anatomist born in 1822 who studied the cardiovascular systems of reptiles and later the mammalian auditory system.

Organ of Corti

A structure located on the basilar membrane of the cochlea containing hair cells that convert sound vibrations into nerve impulses, described by Alfonso Corti in 1851.

$O_2$ utilisation

Process by which organisms indirectly break down simple molecules like glucose, amino acids, and fatty acids to derive energy.

Breathing (Respiration)

The process of exchange of $O_2$ from the atmosphere with $CO_2$ produced by the cells.

Sponges and Coelenterates

Lower invertebrates that exchange $O_2$ with $CO_2$ by simple diffusion over their entire body surface.

Earthworms

Organisms that use their moist cuticle for the exchange of gases.

Insects

Organisms that have a network of tubes (tracheal tubes) to transport atmospheric air within the body.

Branchial respiration

Respiration using special vascularised structures called gills, used by most aquatic arthropods and molluscs.

Pulmonary respiration

Respiration using vascularised bags called lungs, used by terrestrial forms for gas exchange.

Amphibians (e.g., frogs)

Vertebrates that can respire through lungs and also through their moist skin.

Cutaneous respiration

The process of respiring through the moist skin, practiced by animals like frogs.

Pharynx

A portion of the human respiratory system that serves as a common passage for food and air.

Larynx

A cartilaginous box in the respiratory tract which helps in sound production and is called the sound box.

Epiglottis

A thin elastic cartilaginous flap that covers the glottis during swallowing to prevent the entry of food into the larynx.

Trachea

A straight tube extending up to the mid-thoracic cavity which divides into primary bronchi.

$5^{th}$ thoracic vertebra

The level at which the trachea divides into a right and left primary bronchi.

Conducting part

The part of the respiratory system from the external nostrils up to the terminal bronchioles.

Respiratory (Exchange) part

The part of the respiratory system consisting of the alveoli and their ducts where actual diffusion of gases occurs.

Pleura

A double-layered membrane covering the lungs, containing pleural fluid that reduces friction on the lung-surface.

Outer pleural membrane

The layer of the pleura in close contact with the thoracic lining.

Inner pleural membrane

The layer of the pleura in contact with the lung surface.

Thoracic chamber (Dorsal boundary)

The part of the air-tight chamber formed by the vertebral column.

Thoracic chamber (Ventral boundary)

The part of the air-tight chamber formed by the sternum.

Thoracic chamber (Lateral boundary)

The part of the air-tight chamber formed by the ribs.

Thoracic chamber (Lower boundary)

The part of the air-tight chamber formed by the dome-shaped diaphragm.

Inspiration

The stage of breathing during which atmospheric air is drawn into the lungs.

Expiration

The stage of breathing by which the alveolar air is released out of the lungs.

Intra-pulmonary pressure (Inspiration)

Pressure within the lungs that must be less than atmospheric pressure for air to move in.

Intra-pulmonary pressure (Expiration)

Pressure within the lungs that must be higher than atmospheric pressure for air to move out.

Diaphragm and Intercostals

The primary set of muscles that help in the generation of pressure gradients for breathing.

Antero-posterior axis

The axis along which the thoracic chamber volume increases due to the contraction of the diaphragm.

Dorso-ventral axis

The axis along which the thoracic chamber volume increases due to the contraction of external inter-costal muscles.

Normal breathing rate

A healthy human breathes an average of $12-16$ times/minute.

Spirometer

An instrument used to estimate the volume of air involved in breathing movements for clinical assessment of pulmonary functions.

Tidal Volume (TV)

The volume of air inspired or expired during a normal respiration, approximately $500$ mL.

TV per minute

A healthy man can inspire or expire approximately $6000$ to $8000$ mL of air per minute.

Inspiratory Reserve Volume (IRV)

The additional volume of air a person can inspire by a forcible inspiration, averaging $2500$ mL to $3000$ mL.

Expiratory Reserve Volume (ERV)

The additional volume of air a person can expire by a forcible expiration, averaging $1000$ mL to $1100$ mL.

Residual Volume (RV)

The volume of air remaining in the lungs even after a forcible expiration, averaging $1100$ mL to $1200$ mL.

Inspiratory Capacity (IC)

The total volume of air a person can inspire after a normal expiration ($TV + IRV$).

Expiratory Capacity (EC)

The total volume of air a person can expire after a normal inspiration ($TV + ERV$).

Functional Residual Capacity (FRC)

The volume of air that will remain in the lungs after a normal expiration ($ERV + RV$).

Vital Capacity (VC)

The maximum volume of air a person can breathe in after a forced expiration (includes $ERV$, $TV$, and $IRV$).

Total Lung Capacity (TLC)

The total volume of air accommodated in the lungs at the end of a forced inspiration ($RV + ERV + TV + IRV$).

Partial pressure

The pressure contributed by an individual gas in a mixture of gases, represented as $pO_2$ or $pCO_2$.

$pO_2$ (Atmospheric Air)

$159$ mm Hg.

$pO_2$ (Alveoli)

$104$ mm Hg.

$pO_2$ (Deoxygenated Blood)

$40$ mm Hg.

$pO_2$ (Oxygenated Blood)

$95$ mm Hg.

$pO_2$ (Tissues)

$40$ mm Hg.

$pCO_2$ (Atmospheric Air)

$0.3$ mm Hg.

$pCO_2$ (Alveoli)

$40$ mm Hg.

$pCO_2$ (Deoxygenated Blood)

$45$ mm Hg.

$pCO_2$ (Oxygenated Blood)

$40$ mm Hg.

$pCO_2$ (Tissues)

$45$ mm Hg.

$CO_2$ solubility

$20-25$ times higher than the solubility of $O_2$.

Diffusion membrane layers

Consists of three layers: thin squamous epithelium of alveoli, endothelium of alveolar capillaries, and an intervening basement substance.

Diffusion membrane thickness

The total thickness is much less than a millimetre.

Oxygen transport in RBCs

About $97$ per cent of $O_2$ is transported by RBCs in the blood.

Oxygen transport in Plasma

About $3$ per cent of $O_2$ is carried in a dissolved state through the plasma.

$CO_2$ transport as bicarbonate

Nearly $70$ per cent of $CO_2$ is carried as bicarbonate.

$CO_2$ transport in RBCs

Nearly $20-25$ per cent of $CO_2$ is transported by RBCs.

$CO_2$ transport in Plasma

About $7$ per cent of $CO_2$ is carried in a dissolved state through plasma.

Haemoglobin

A red coloured iron-containing pigment present in the RBCs that binds reversibly with $O_2$.

Oxyhaemoglobin

The complex formed when oxygen binds with haemoglobin.

Haemoglobin oxygen capacity

Each haemoglobin molecule can carry a maximum of four molecules of $O_2$.

Oxygen dissociation curve

A sigmoid curve obtained when the percentage saturation of haemoglobin with $O_2$ is plotted against the $pO_2$.

Favourable factors for Oxyhaemoglobin (Alveoli)

High $pO_2$, low $pCO_2$, lesser $H^+$ concentration, and lower temperature.

Favourable factors for $O_2$ dissociation (Tissues)

Low $pO_2$, high $pCO_2$, high $H^+$ concentration, and higher temperature.

$O_2$ delivery to tissues

Every $100$ ml of oxygenated blood can deliver around $5$ ml of $O_2$ to the tissues under normal physiological conditions.

Carbamino-haemoglobin

The form in which approximately $20-25$ per cent of $CO_2$ is carried by haemoglobin.

Carbonic anhydrase

An enzyme present in high concentration in RBCs and minute quantities in plasma that facilitates the formation of bicarbonate.

Bicarbonate reaction Equation

$$CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons HCO_3^- + H^+$$

$CO_2$ delivery to alveoli

Every $100$ ml of deoxygenated blood delivers approximately $4$ ml of $CO_2$ to the alveoli.

Respiratory rhythm centre

A specialised centre in the medulla region of the brain primarily responsible for the regulation of respiration.

Pneumotaxic centre

A centre in the pons region of the brain that can moderate the functions of the respiratory rhythm centre.

Pneumotaxic centre function

Can reduce the duration of inspiration and thereby alter the respiratory rate.

Chemosensitive area

An area adjacent to the rhythm centre highly sensitive to $CO_2$ and hydrogen ions.

Aortic arch and carotid artery receptors

Receptors that recognise changes in $CO_2$ and $H^+$ concentration and signal the rhythm centre for remedial actions.

Asthma

A difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles.

Emphysema

A chronic disorder in which alveolar walls are damaged, decreasing the respiratory surface, majorly caused by cigarette smoking.

Occupational Respiratory Disorders

Diseases resulting from long exposure to dust in industries like grinding, leading to inflammation and fibrosis.

Fibrosis

Proliferation of fibrous tissues causing serious lung damage, often seen in workers in stone-breaking industries.

Conducting part functions

Transports atmospheric air to alveoli, clears foreign particles, humidifies air, and brings air to body temperature.

Simple diffusion

The mechanism by which sponges, coelenterates, and flatworms exchange gases.

Tracheal tubes

A network of tubes used by insects to transport atmospheric air within the body.

Gills

Vascularised structures used for branchial respiration in aquatic arthropods and molluscs.

Vertebrate respiration types

Fishes use gills; amphibians, reptiles, birds, and mammals use lungs; amphibians also use skin.

Nasal chamber

An internal space leading from the nostrils that opens into the pharynx.

Cartilaginous rings

Incomplete structures that support the trachea, primary, secondary, and tertiary bronchi, and initial bronchioles.

Alveoli

Very thin, irregular-walled, and vascularised bag-like structures that are the primary sites of gas exchange.

Pleural fluid

Fluid situated between the two pleural membranes that reduces friction on the lung surface.

Thoracic cavity

An anatomically air-tight chamber in which the lungs are situated.

Pulmonary ventilation

The first step of respiration where atmospheric air is drawn in and $CO_2$ rich alveolar air is released out.

Diffusion of gases

Movement of $O_2$ and $CO_2$ across the alveolar membrane or between blood and tissues.

Pressure gradient

Difference in pressure between the lungs and atmosphere that carries air into and out of the lungs.