functions of the respiratory system

 what about sharks that lack a bony operculum? by swimming forwards, a continuous flow of water passes over their gills = ram ventilation. some sharks can lie on the sea floor and breathe without swimming by sucking water into their mouths using large cheek muscles = buccal ventilation. Obligate ram ventilators do not exhibit  buccal pumping. sharks such as the great white and whale sharks die from lack of oxygen if they stop swimming

      Respiratory System Pathology

      Asthma

Evolution of the Respiratory System

      why do
​ you breathe??

      Vaping

respiration via spiracles

   Pneumonia

Arthropod gas exchange takes place via
tubes called tracheae. Air enters the trachea through spiracles then diffuses into the body tissue. CO2 waste released from the cells goes into the tracheal tubes and comes out through spiracles.
The tracheal tubes (but not the tracheoles) are molted along with the rest of the exoskeleton. Tracheae are
unique to various arthropods.
The small, external spiracle reduces
water loss and the chitinous lining prevents collapse. Since arthropods are relatively small, the short length of the tracheal tube permits simple diffusion
of gasses into the animal. 

 The Reproductive System

      COPD

  where does the CO2 come from??

respiration via diffusion

   control of respiration

 Some animals which live on land have skin which is so thin that gases can easily pass through it. For example, Earthworms and amphibians have a skin which is permeable to gases. Earthworms do not have lungs and breathe only through their skin.

 RBC dropping off O2/picking up CO2 in tissues

respiration via "book lung"

the Palaeozoic ~400 million years ago water-to-land transition
drove key physiological modifications like the evolution of the lung. evidence suggests that the common ancestor of the lobe/ray-finned fishes had lungs as well as gills. In the lobefins, lungs stuck around. tetrapods, coelacanths, and
lungfish, all inherited them. Coelacanths and lungfish also retained their gills. Modern tetrapods, on the other hand, bear evidence indicating that we once had gills but that these were lost in the course of our early evolution. In ray finned fish, the lungs evolved into the swimbladder used for buoyancy.
​during vertebrate embryonic development, gill slits develop, called pharyngeal slits. In humans, these pharyngeal slits eventually develop into the inner ear but their presence
 shows the shared common ancestry between all chordates.

respiration via gills

      Cancer

      Cystic Fibrosis

   Solubility to pressure: Dalton's Law

 RBC picking up O2/dropping off CO2 in alveoli

A book lung is present in scorpions and spiders.
​ It's located inside an abdominal, air-filled cavity that is open to the atmosphere through a small opening. Book lungs are not homologous to the lungs of modern terrestrial vertebrates. they get their name from their stacks of alternating air pockets and tissue filled with hemolymph that looks like a folded book. The "pages" of the book lung are filled with hemolymph with the many folds increasing the surface exposed to air. The internal pockets of the book lungs are lined with chitin for support. 

 Covid and the ACE2 receptor

Evolution of the Respiratory System

Gills permit aquatic animals to breathe underwater. But they also regulate the salt and pH balance in fish blood similar to what kidneys do in other animals. This ion regulation evolved even before gills were used for breathing. These two functions previously carried out by diffusion helped vertebrates evolve from small, worm-like creatures to larger fish. Lampreys are vertebrates, and amphioxus are their close relatives.
The simple gills of their shared ancestor
evolved over 500 million years ago.

the vertebrate lung

      How is CO2 carried by the blood?   

    what's hemoglobin?

Annelids use their thin, moist skin for the exchange of gases. The exchange of gases occurs via surface capillaries.
Amphibians such as frogs use more than one organ of respiration during their life. They breathe through gills while they are tadpoles but when they mature, frogs breathe mainly via lungs and gas exchange through their skin.

and that pesky,
marvelous
​  echinoderm...