transport systems

• Exchange of materials

  All enter and leave via capillaries

  OXYGEN:

  • Enters via alveoli of lungs
  • Leaves into tissue of body

  CARBON DIOXIDE

  • enter via body tissues (not lunsg)
  • leaves into alveoli of lungs, breathed out

  GLUCOSE/FATTY ACIDS/AMINO ACIDS ETC

  • enter via epithelium of villi of small intestine
  • leave into tissue of rest of body to cells for growth

  HORMONES

  • released by glands
  • leave into target organs

  UREA

  • enters via liver
  • leaves from kidneys in urine
• Haemoglobin

  • Most oxygen in blood carried by hemoglobin in red cells, some dissolved in plasma.
  • Hemoglobin, a protein with iron, grabs oxygen in lungs, forming oxyhemoglobin.
  • Each hemoglobin can hold four oxygen molecules.
  • Deoxygenated blood enters lung capillaries.
  • Oxygen from alveoli diffuses into blood via concentration gradient, binds with hemoglobin to form oxyhemoglobin.
  • Oxygen-rich blood travels to tissues.
  • In tissues, oxyhemoglobin releases oxygen, used for cellular respiration.
• Advantages of haemoglobin

  • high affinity for oxygen, in the lungs where the oxygen levels are high, becoming fully saturated.
  • In tissues with lower oxygen levels, like muscle tissue during exercise, hemoglobin releases some oxygen to the active cells.
• Oxygen haemoglobin dissociation curve

  1. Curve shows hemoglobin's relationship with oxygen being carried VS oxygen in the environment .
  2. High oxygen: Hemoglobin holds tight.
  3. Low oxygen: Hemoglobin lets go.
  4. Helps understand oxygen delivery efficiency.
• blood, tissue fluid, lymph

  • Blood in arterioles carry nutrients and oxygen
  • High pressure due to heart contraction at arteriole end of capillaries push plasma
  • Plasma filtered: pushing out water, glucose etc
  • Nutrients move into cells, waste move into tissue fluid.
  • Blood pressure decreases as blood flows in capillaries.
  • Low pressure at venous end of capillaries allows some plasma to be reabsorbed.
  • Large plasma proteins create lower water potential, drawing water into blood.
  • Excess tissue fluid = lymph in lymph capillaries.
  • Lymph returns to blood via lymph vessels and subclavian veins.
• respiratory surfaces general

  • Large surface area (SA) for rapid diffusion.
  • Thin cells for a short diffusion pathway.
  • Extensive blood supply to maintain a high diffusion gradient.
  • Ventilation mechanism for fresh oxygen supply and carbon dioxide removal, maintaining a high diffusion gradient.
• Gas exchange in mammals

  • Gas exchange in mammals occurs in the lungs:
  • Trachea: Supported by cartilage rings to prevent collapse during pressure changes.
  • Bronchi: Branches from the trachea, further dividing into bronchioles.
  • Alveoli: Small air sacs at the end of bronchioles where gas exchange happens.
• Alveoli adaptations for gas exchange:

  • Shape and abundance create a large surface area.
  • Fluid lining allows gases to dissolve and diffuse.
  • Only two cell layers separate blood and air, providing a short diffusion pathway.
  • Surrounding blood capillaries absorb oxygen and release carbon dioxide.
• Ventilation meaning

  • Ventilation refers to passing air (or water in fish) over the respiratory surface to maintain a diffusion gradient.
  • In mammals, the respiratory center in the brain's medulla sends nerve impulses to breathing muscles.
• Inspiration (Breathing in):

  1. External intercostal muscles contract, moving the ribcage upwards and outwards.
  2. Diaphragm muscles contract, causing it to flatten.
  3. These actions increase thoracic volume.
  4. Thoracic pressure decreases below atmospheric, allowing air to enter the lungs.
• Expiration (Breathing out):

  • Mainly a passive process.

  1. External intercostal muscles relax, causing the ribcage to move downwards and inwards.
  2. Diaphragm muscles relax, returning it to its dome shape.
  3. These actions decrease thoracic volume.
  4. Thoracic pressure increases above atmospheric, forcing air out of the lungs.
• Gaseous Exchange in Fish:

  • In bony fish, gas exchange occurs over the gill surfaces, protected by the operculum.
  • Gill structure:

  1. Four pairs of gill arches, each with rows of gill filaments containing lamellae (thin plates) for increased surface area.
  2. Thin barrier separating blood and water, with only two cell layers.
• what is gas exchange?

  The process of exchanging oxygen and carbon dioxide between an organism and its environment.

  It occurs across specialized respiratory surfaces, like lungs or gills, enabling cells to produce energy and remove waste.
• Gas exchange adaptations for fish

  1. Gill Structure: Fish have specialized gills + large surface area of gills + lamellae, allowing for efficient gas exchange.
  2. Countercurrent System: Blood + water flow in opposite directions over gill lamellae, maximizing diffusion of oxygen into blood along entire gills
  3. Rich Blood Supply: The gill lamellae have abundant supply of blood capillaries, high concentration gradient for oxygen uptake.
  4. Ventilation Mechanism: Fish have ventilation mechanism, continuously brings water over gills, fresh supply of oxygen-rich water and facilitating gas exchange.
• Inspiration (fish):

  1. Mouth opens, increasing its volume.
  2. Water enters through the mouth into the buccal cavity.
  3. Opercular valve shuts, enlarging opercular cavity.
  4. Water is forced from buccal cavity into opercular cavity and over the gills.
• Expiration (fish):

  1. Mouth closes, reducing buccal cavity volume.
  2. Pressure in buccal cavity increases, forcing water into opercular cavity and over gills.
  3. Pressure in opercular cavity rises, expelling water through opercular valve.
• Gas exchange plants

  • Numerous small stomata enhance diffusion.
  • Leaves are thin for efficient exchange.
  • Mesophyll cells and air spaces provide a large exchange surface.
  • Diffusion occurs across thin cell walls and membranes.
• Insect ventilation?

  • Insects breathe through spiracles.
  • Oxygen enters spiracles and dissolves into fluid in tracheoles.
  • Oxygen moves into cells through phospholipid part of membranes.
  • Carbon dioxide exits cells through the same pathway.
  • Activity boosts breathing: muscles squeeze trachea, spiracles open wider, lactic acid helps draw air to cells.
  • During rest, spiracles close to conserve water.
• • Normal breathing rate is controlled by:
  • Inspiratory center sends impulses -> external intercostal and diaphragm muscles. .
  • Muscles contract, lungs inflate.
  • Stretch receptors in bronchiole walls stimulated.
  • Receptors send impulses to expiratory centre..
  • Expiratory centre inhibits inspiratory centre.
  • Muscles relax, lungs deflate.
  • Deflation stops stimulation of stretch receptors.
  • Inspiratory centre no longer inhibited sends impulses to stimulate inspiration.
• Exercise and breathing

  • Exercise increases respiration rate, producing more carbon dioxide.
  • Carbon dioxide dissolves in blood, forming carbonic acid and increasing hydrogen ion concentration.
  • Chemoreceptors, located in aortic, carotid bodies, and medulla, are stimulated by increased hydrogen ions and carbon dioxide.
  • Stimulated chemoreceptors send more nerve impulses to medulla's respiratory center.
  • Respiratory center sends more impulses to muscles, increasing breathing rate.
  • Breathing rate remains high until blood carbon dioxide concentration returns to normal.