Tetrapods Flashcards
Terrestrial vertebrates respiration
Respiratory airways conducts air between the atmosphere and the gas exchange surfaces.
Ventilation moves air through the airways into and out of the lungs. Amphibians and some reptiles have air forced into the lungs whilst reptiles, birds and mammals have air flowing in because of a negative pressure caused by the expansion of the rib cage and muscular contraction.
Respiratory system of tetrapods include
The respiratory airways, lungs and thoracic structures involved in ventilation.
Ventilation: Amphibians
The air enters the pocket of the buccal cavity. The Glottis opens and there is an elastic recoil of lungs and compression of the chest wall which reduces the lungs volume. Air is this forced out of the lungs and nares. The nares close and the floor of the buccal cavity rises and air is pushed into the lungs. The glottis then closes and gas exchange occurs in the lungs.
Ventilation: Mammals and reptiles
Breathing is an alternation between inhalation and exhalation. It is the mixing of pre- and post-exchange air.
Inhalation is active and involves the expansion of the thoracic cavity where the lungs become inflated by negative pressure. It involves the contraction of the intercostal muscles in most reptiles and the intercostal muscles and diaphragm of mammals and some reptiles.
Exhalation is usually passive and involves the contraction of the thoracic cavity where air is pushed out by positive pressure. It involves the relaxation of muscles.
Muscles involved in inhalation
Sternocleidomastoid muscle Scalene muscles Pectoralis minor muscle Serrated anterior muscle External intercostal muscles Diaphragm
Muscles involved in exhalation
Transversus thoracic muscle
Internal intercostal muscles
Rectus abdominis and other abdominal muscles.
Geometric arrangements of the structural components
Cross current gas exchange
Countercurrent gas exchange
Uniform pool gas exchange
Models for respiratory gas exchange:
OPEN EXCHANGE
Cutaneous exchange.
Oxygen goes to the capillaries and CO2 is produced which is placed back in the air.
It a constant exchange.
Models for respiratory gas exchange:
UNIFORM POOL EXCHANGE
Mammalian lung.
Ventilation through tidal flow.
Gas exchange occurs at each breath. Osmotic pressure of oxygen is uniform in the exchanger (lungs).
Models for respiratory gas exchange:
CROSSCURRENT EXCHANGE
Avian lung.
The alveoli are arranged radially, with tidal flow ventilation in the air sacs.
Airflow is unidirectional, with the assistance of parabronchi.
Gas exchange occurs at each breath.
Air enters the parabronchus at a high oxygen osmotic pressure which then decreases.
Bronchi
An airway in the respiratory tract that conducts air into the lungs.
Metazoans Circulatory System
In order to overcome the limits of diffusion.
The movement of the medium (blood) is does the bulk of the transport.
It moves the nutrients, gases, wastes, hormones, immune defenses and heat.
It’s functions are transportation, regulation and protection.
Circulatory system is made up of
A fluid (blood/hemolymph) which carries the molecules of interest. A pump (heart) which moves the fluid. And vessels that carry the fluid between the pump and the tissues. Although enclosed vessels are absent in many animals.
Open Circulatory system
Hemolymph bathes tissues directly.
The heart pumps the hemolymph through a network of open-ended channels.
This is present in most mollusks, and in all arthropods.
Closed Circulatory system
The circulating fluid, blood, is not the same as the extracellular fluid. The blood is kept in vessels. The heart is necessary.
This method is more efficient than the open circulatory system.
Present in cephalopods, annelids and vertebrates.
