Comparative Physiology Midterm 2 Vocabulary Review

Comprehensive vocabulary flashcards covering primate bipedalism, the physics of respiration, gas exchange models across taxa, and cardiovascular diversity as detailed in the lecture transcript.

Brachiation

Arm-swinging arboreal locomotion; true brachiators like gibbons can reach speeds of approximately $35\,mph$ and covers $20\,feet$ per swing.

True Bipedalism

A form of locomotion where the spine runs perpendicular to the direction of movement and body weight is distributed over only two legs.

Kyphoses

Primary vertebral curvatures (thoracic and sacral) that are concave ventrally and shaped by the vertebral bodies, resembling the single fetal spinal curve.

Lordoses

Secondary vertebral curvatures (cervical and lumbar) that are concave dorsally, shaped by intervertebral discs, and molded through development and use.

Angle of Inclination

The angle at which the femoral head is set away from the shaft; it becomes less obtuse with age and is typically less obtuse in females.

Nuchal Ligament

A stretchy connective-tissue band in humans that attaches the rhomboids and trapezius to the skull, acting as a shock absorber to reduce head bounce during running.

Boyle's Law

The principle stating that the volume of a gas is inversely proportional to its pressure ($PV = nRT$), explaining bulk airflow through cavity expansion and compression.

Dalton's Law

The principle stating that the total pressure of a gas mixture is equal to the sum of the partial pressures of each component gas.

Henry's Law

The principle stating that the amount of gas dissolved in a liquid is directly proportional to the gas's partial pressure in contact with that liquid.

Fick's First Law of Diffusion

The formula defining the rate of diffusion as $\text{Rate} = (Area \times Concentration\,difference) / Distance$.

Countercurrent Flow

The most efficient gas exchange mechanism where blood and water flow in opposite directions, maintaining an oxygen gradient across the entire exchange surface; seen in fish gill lamellae.

Crosscurrent Flow

A gas exchange model where air flows in one direction and blood flows perpendicularly across it through capillary rungs; seen in bird parabronchi.

Uniform Pool

A gas exchange model where gas mixes into a homogeneous pool driven by blood-concentration changes; characteristic of mammalian alveoli.

Respiratory Cascade

The progression of oxygen partial pressure ($PO_2$) from ambient air to alveolar gas, then to arterial, capillary, and finally venous blood.

Ram Ventilation

Passive gas exchange where fish swim with their mouths open to let water flow over the gills, used by active swimmers like sharks, mackerel, and tuna.

Physostomic Fish

Also known as "gulpers," these fish possess a connection between the digestive tract and the swim bladder, used as a model for the fish-to-tetrapod transition.

Estivation

A state of "summer sleep" used by lungfish during seasonal drying, where the metabolic rate and oxygen demand drop to approximately $1/60th$ of normal.

Gular Breathing

A respiratory assist mechanism in squamates (lizards/snakes) that uses hypobranchial muscles and positive pressure to draw air into the lungs, compensating for lateral undulation.

Hepatic Piston

A ventilatory mechanism in crocodilians where the diaphragmaticus muscle pulls the liver posteriorly to drive inspiration.

Gastralia

Dermal, rib-like bones in the abdominal region of reptiles; their contraction and relaxation drive negative-pressure ventilation.

Faveolar Lungs

Lungs with one central chamber and lateral septation ending in terminal membranes; typical of sauropsids (reptiles and birds).

Anatomical Dead Space

The regions of the respiratory tract from the nose through the terminal bronchioles where no gas exchange occurs.

Type I Alveolar Cells

Squamous epithelium cells that form the respiratory membrane and serve as the actual site of gas exchange.

Type II Alveolar Cells

Cells that secrete surfactant to reduce surface tension between alveolar walls, preventing them from sticking shut.

P50

A standardized benchmark representing the partial pressure of oxygen ($PO_2$) at which $50\%$ of a respiratory pigment's binding sites are saturated.

Sinoatrial (SA) Node

The innate/endogenous pacemaker of the vertebrate heart, positioned in the right atrium at the base of inflow vessels.

Intercalated Discs

Gap junctions that electrically link cardiac muscle cells, allowing the whole heart to contract as a single syncytium.

Conus Arteriosus

In fish, a valve-filled elastic chamber that maintains pressure in the ventral aorta and prevents backflow during ventricular relaxation.

Foramen of Panizza

A unique anatomical connection between the two aortas in crocodilians that allows the left ventricle to feed both arches during normal activity.