Gas exchange Systems

Description

A level Biology Mind Map on Gas exchange Systems, created by Jumael Zafar on 18/08/2017.
Jumael Zafar
Mind Map by Jumael Zafar, updated more than 1 year ago
Jumael Zafar
Created by Jumael Zafar about 7 years ago
13
1

Resource summary

Gas exchange Systems
  1. Animals
    1. Fishes have gills through which they exchange gasses.
      1. Counter-current occurs where water and blood flow in the opposite directions, via the lamellae and Gill filaments. Oxygen diffuses into the blood
        1. Both these features have a large surface area making the gas exchange more efficient and faster.
          1. This happens continuously so that a concentration gradient is maintained. This means diffusion can occur continuously.
        2. Humans have lungs where gas exchange occurs, between the alveoli and the capillaries.
          1. When we inhale, our diaphragm and external intercostal muscles contracts, increasing the volume of the thorax, so Oxygen diffuses in.
            1. When we exhale, our internal intercostal muscles contracts, and the others relax, decreasing the volume but increases pressure, forcing Carbon Dioxide out.
              1. The Oxygen travels down our trachea, through the bronchi, through little bronchioles, into the alveoli.

                Annotations:

                • Alveoli have a one cell thick, and permeable membrane, allowing efficient gas exchange and fast. There are many of them which increases their surface area.
                • Due to a continuous blood circulation, a concentration gradient  is maintained so that Oxygen can always diffuse into the blood.
                1. The Oxygen travels from the alveoli, through the alveolar epithelium, and through the capillary endothelium into the blood.
          2. Insects
            1. They have spiracles through which their gasses exchange, and there are many of them, which increases their surface area.

              Annotations:

              • The spiracles open when gas exchange is requires and close when too much water is being lost, so that the insect does not get dehydrated.
              1. The Oxygen diffuses through into the tracheoles where it diffuses into the cells, ready for respiration
            2. Plants
              1. Gas exchange occurs at the stomata (bottom of a leaf), which opens and closes, and is controlled by the guard cells. Stomata are gaps between mesophyll cells, at the lower epidermis.
                1. Usually, the stomata closes when too much water is being lost, and the guard cells become flaccid, however, if water enters the plant, it becomes turgid opening the stomata.
                2. Xerophytes (plants in heat)
                  1. These have specific features that allow them to adapt to warm conditions, by reducing water.
                    1. A waxy cuticle on surface to reduce evaporation.
                      1. Sunken stomata which traps water vapour.
                        1. A layer of hair on the epidermis to reduce water vapor around the stomata.
                          1. Leaves reduced to spines to reduce the amount of water lost by evaporation via leaves.
                      2. Single-celled organisms
                        1. Oxygen diffuses directly into these cells, as they are so tiny and have such a large surface area, the diffusion pathway is very small, and this makes the process faster.
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