gas exchange

• The process by which organisms require oxygen for metabolism is called respiration
• In plants, carbon dioxide, a waste product of respiration, is needed for photosynthesis.
• Animals have to take in oxygen and expel carbon dioxide in order

  to survive
• Gas exchange is one of the essential prerequisites for life to

  continue.
• Diffusion is a process by which molecules move from an area of higher concentration to an area of lower concentration in the direction following a concentration gradient.
• In order to survive, animals need to take in oxygen and expel

  carbon dioxide.
• The exchange of gases through inhalation and exhalation is called respiration.
• Air is a respiratory medium with plentiful O2. Water has

  much less oxygen and greater density and viscosity, making gas

  exchange more challenging in water than in air.
• The skin or the body surface system is also known as

  the integumentary system
• Animals that live in moist environments

  like worms and amphibians used their moist body surface to

  breathe in oxygen. skin system
• Gills are thin tissue filaments

  that are highly branched and folded.
• Fish and other aquatic animals use their gills to take

  up the dissolved oxygen from water
• gas exchange system: skin system, gills system, tracheal system, lung system
• Insects,

  such as grasshoppers and

  spiders, use their tracheae to

  facilitate gas exchange.
• Tracheae consist of air tubes

  called spiracles forming

  network in the bodies of

  insects.
• A pair of organs divided into small chambers

  filled with capillaries called lungs are found inside the cavity of

  land animals such as humans.
• The tube that connects the nose

  and mouth to the lungs is called

  trachea.
• The trachea divides into

  two main bronchi (singular:

  bronchus) (the left and right)

  which further subdivides into

  bronchioles.
• The tip of each

  bronchiole is called alveolus

  (plural: alveoli) wherein actual

  gas exchange occurs.
• Lying flat

  at the bottom of the chest cavity

  (under the lungs) is the

  diaphragm, a large muscle

  that aids in breathing by

  moving up and down.
• The rib

  cage encloses the lungs and

  protects the respiratory organs

  and the heart.
• Air is inhaled

  through the nasal cavity and crosses the surfaces of the mucous

  membrane.
• From the nasal cavity, air passes through the pharynx

  and the larynx to the trachea
• When we breathe in or inhale, the diaphragm contracts
• When we

  breathe out or exhale, the diaphragm relaxes
• Diffusion occurs in leaves, roots, and stems.
• Plants exchange their gases with the environment in a

  straightforward way.
• Diffusion is the only process

  through which much needed oxygen is supplied to all the cells of

  the plants.
• Plant leaf consists of stomata (singular: stoma) that allow gas

  exchange between the surrounding air and the photosynthetic

  cells inside the leaf.
• In between the upper and lower epidermal layers of a leaf is

  a region called the mesophyll (from the Greek words mesos:

  middle, phyll: leaf)
• Plant roots take oxygen from

  the air that is present in between

  the particles of soil
• Root hair, an

  extension of the root epidermal

  cells, is in direct contact with the

  soil.
• Lenticels are in the small area of a bark.
• The

  circulatory system functions to support life as it feeds our cells with

  food and oxygen. Part of the task of this system is the removal of

  waste products.
• The heart and the blood vessels function to transport

  substances and together form the circulatory system
• There are two divisions

  of the circulatory system:

  the lymphatic division

  (helps return tissue to the blood) and the blood division (a closed

  circuit).
• This

  general body fluid is more

  correctly called

  hemolymph.
• There are three main parts of the circulatory system: the

  heart, blood vessels, and blood.
• The heart is

  divided into two chambers: the top chamber called atrium (plural:

  atria) and the bottom chamber called the ventricle.
• The heart is a bundle of muscles about the size of the fist.