Respiration

• Sponges

  These organisms and others with simple

  body organization exchange gas with the

  environment by diffusion through their cell

  membranes
• In animals with complex body organization, it is carried out in a somewhat complex way, i.e., through a respiratory system.
• However, the majority of macroscopic aquatic animals use gills for gas exchange, an aquatic adaptive organ that is equivalent to the lungs in most terrestrial animals.
• In fishes, the heart is two-chambered.
• When the atrium receives the blood, it is channeled to the ventricle. The contraction of the ventricle of the heart pumps blood to the conus arteriosus that pulsates and transfers blood to the gills,

  where gas exchange happens
• Gas exchange is made more efficient through the

  countercurrent flow, where the blood and water meet in opposite directions.
• Breathing is an involuntary process that

  occurs simultaneously with blood

  circulation.
• we obtain oxygen which eventually is transported to the rest of the body by hemoglobin
• waste products such as carbon dioxide are being excreted through the process of exhalation
• External Respiration

  ➢ The respiration is the exchange of gases between the atmosphere and the lungs
• The air passing through the nose is filtered in the presence of coarse hairs projecting from

  the inner walls of the nostrils.
• mucous membrane, a layer of specialized cells which secrete mucus, lines the walls of the

  nasal passages.
• cilia, the microscopic hairs on the surface cells of the mucous membrane, move back and forth at all times to move any material in it to the outside of the nose
• Pharynx

  also known as throat, is found at

  the back of the mouth, contains

  the passageways for food and air
• When food is swallowed, a flap of

  cartilage called epiglottis presses

  down and covers the opening of

  the air passage.
• During inhalation, the epiglottis

  is in an upright position and air

  moves into the trachea or

  windpipe
• Larynx

  ➢ is also called voice box or

  Adam's apple
• Larynx

  ➢ located at the upper end of the

  trachea and is primarily involved

  in sound production
•  Sounds are produced when air is forced past two vocal cords that stretch across the larynx.
• Trachea

  also called windpipe, is located in

  front of the esophagus
• Trachea

  ➢ It is about 10 cm long and 2.5 cm

  wide and is lined with mucous

  membranes and cilia.
• Bronchi

  ➢ The trachea is divided into two

  hollow branches called bronchi

  (singular, bronchus).
• ➢ Each bronchus is attached to a lung.

  ➢ The inner lining of the bronchi is

  lined with cilia and mucus that help

  filter air.
•  Lungs are large, spongy, and elastic

  saclike structures suspended from

  each side of the heart, inside the

  chest cavity
• ➢ Inside the lungs, the bronchus

  divides into smaller branches, the

  bronchial tubes, branching

  repeatedly into even smaller

  microscopic tubes called

  bronchioles
• Each bronchiole opens into thin- walled, bulb-shaped structures called air sacs or alveoli.
• Each alveolus is surrounded by a network of capillaries that are

  important in gas exchange between the blood and the air sacs.
• Internal Respiration

  It involves gas exchange between the blood and the

  cells of the body.
• Blood in the capillaries surrounding the air sacs

  are low in oxygen and rich in carbon dioxide
• Thus, gases move by diffusion from these areas of higher

  concentration to areas of lower concentration.
• Air moving into then alveoli is rich in oxygen and poor in carbon dioxide
• LENTICELS

  small elevated and oval-shaped

  structures along the stem
• Stomata

  "breathing organs" of plants
• Stomata

  are minute openings in the leaves

  of plants flanked by a pair of

  sausage-shaped cells called guard

  cells
• ➢ Stomata serve as entry and exit

  points of gases in plants.
• ➢ The stomata also serve as

  passageways for the transpiration

  of water through the leaves during

  hot and windy days.
• ➢Turgor pressure in guard cells is responsible for

  the opening and closing of the stomata.
• In guard cells, active uptake of potassium, malate, and chlorine ions causes an increase in the concentration of solute inside the guard cells.
• When this happens, water outside of the guard cells will move osmotically inside the cell, making it turgid and causing the stomata to open
• At nighttime, sucrose produced during the day isvunloaded to the outside of the guard cells, resulting invloss of turgor. When this happens, guard cells become flaccid,

  resulting in the closing of the stomata.