NAl Gas exchange student.pdf Powerpoint Presentation

Powerpoint on everything gas exchange

2. Cos its been a while…..
•https://www.youtube.com/watch?v=-
qi7OZzXJjg
•Jam campus

3. Gas exchange
What is the name given to the system involved in gas
exchange (1)
Name the organs of this system (2)
Where is the site of gas exchange in mammals? (1)
What are the adaptations of this site that are suited for
its function? (1)
What are the gases that are exchanged? (2)
What is the name given to the taking in of air into the
lungs? (1)
What is the name given to the expulsion of air from the
lungs? (1)

4. Remember this?
1.
2. 3.
4.
5.
6. Oxygenated blood leaves the heart to
the rest of the body via which vessel?

5. 1.Trachea
2. Bronchus
3. Bronchiole
4. Alveoli
5. Diaphragm
6. Aorta

6. How many parts of the respiratory system can
you label correctly?
EXT: add their functions

7. Trachea
Windpipe
Lung
Takes in oxygen and release
carbon dioxide into the
atmosphere
Diaphragm
Muscle, contracts to allow air to be drawn into the lungs
Ribs
Enable the lungs to expand
Alveoli
Gas exchange surface
Intercostal Muscles
Form and move the chest wall
Bronchus (p) / Bronchi (s)
Allows passage of air to the lungs
Bronchioles
Passageway for the air
Larynx
(Voicebox)
Self-Assess

13. GASEOUS EXCHANGE
THE NEED FOR A RESPIRATORY SURFACE
•In small organisms, surface area : volume ratio is large, so
diffusion is sufficient
•In larger organisms, surface area : volume ratio is small so a
gaseous exchange system has evolved.

14. Features of a respiratory
surface
1.Large surface area for gaseous exchange
2.Moist surface for gases to dissolve
3.Short diffusion distance -alveoli and
capillary walls only one cell thick
4.Richly supplied with capillaries to
maintain a concentration gradient

15. Structure of the gaseous exchange
system
•Pharynx–throat
•Epiglottis–flap of cartilage which seals off trachea
•Larynx–voice box
•Goblet cells –in between ciliated epithelial lining,
secrete sticky mucus (a glycoprotein) to trap
pathogens.
•Cilia–beat rhythmically to sweep mucus up the
trachea at 1cm/min, to be swallowed.
•Macrophages–WBC which scavenge pathogens
from lining of airways.

17. Trachea-main airway
•C-shaped cartilagenousrings keep it
open, and prevent it from collapsing
under changes in air pressure.
•Lined with goblet cells (produce
mucus) and cilia (sweeps mucus with
pathogens up to the larynx to be
swallowed)
•Has elastic fibresand collagen for
stretch and flexibility
•Has smooth muscle –this can contract
and cause spasm (asthma) –
bronchodilators are drugs to relax the
muscles of the airways.

19. Bronchusx2 bronchi
•Irregular cartilagenousblocks
•Goblet cells and cilia
•Smooth muscle
•Elastic fibresand collagen
Bronchioles
•Branches
•No cartilage –allows for muscle
relaxation and contraction, egduring
exercise relaxes to let more air in.
•Cilia and goblet cells
•Smooth muscle
•Elastic fibres

20. Alveolar ducts –small tubes
which join bronchioles and alveoli
Alveolus –single layer of
epithelial cells
•No cartilage
•No muscle
•No goblet cells or cilia
•Elastic fibrespresent to allow
stretch and recoil during inspiration
and expiration, large volume
created
•Secretions from alveolar lining
allow gases to dissolve
•Richly supplied with capillary blood
•Formsgaseous exchange surface.

22. Surfactant :
•a secretion from the alveoli which reduces
surface tension in alveolus wall x10 thus
reducing the effort needed to inflate the
alveoli.
•Antibacterial properties
•Assists diffusion

25. structurecartilagegoblet
cells
cilia Smooth
muscle
Elastic
fibres
Size (mm)
Trachea √
Bronchus √
irregular
√
Bronchioles
Alveoli X
Copy and complete the table

26. structurecartilagegoblet
cells
cilia Smooth
muscle
Elastic
fibres
Size
Trachea √ C-
shaped
√ √ √ √ 18mm
Bronchus √
irregular
√ √ √ √ 12mm
BronchiolesX √ √ √ √ 0.5mm
Alveoli X X X X √ 0.25mm

28. Use your textbooks to describe how
the trachea and lining of lungs are
protected
TASK

29. Pleural membranes
•Line the lungs on the outside and
the thoracic cavity on the inside
forming a pleural sac
•The membrane secretes pleural
fluidwhich reduces friction of
lungs against ribs
•The fluid filled sac is non
compressible , so when the thorax
volume decreases, air is forced out
of the alveoli. When the volume
increases the alveoli ‘stick’ to the
chest wall and are pulled open i.e
inflate thus drawing air in.

30. Alveoli structure

31. Blood flow through the pulmonary capillaries maintains
a concentration gradient.

33. Breathing movements constantly ventilating the
lungs, and action of the heart constantly
circulating the blood around the alveoli.
Concentration gradient is maintained

36. 6 mark question
•Diffusion of gases between the alveoli and the
blood will be very rapid, why?

37. Swap and assess (green pen)
•Red blood cells are slowed as they pass through pulmonary
capillaries, allowing more time for diffusion.
•Reduced distance between alveolar air and red blood cells
•Very tin wall, both alveoli and capillaries. Therefore very
short diffusion pathway.
•Alveoli and pulmonary capillaries have a large surface area
•Breathing movements constantly ventilating the lungs, and
action of the heart constantly circulating the blood around
the alveoli. Concentration gradient is maintained
•Blood flow through the pulmonary capillaries maintains a
concentration gradient.

38. Human Respiratory System

39. Mechanism of Breathing

40. Ventilation
Inspiration:
•External intercostal muscles contract
•Internal intercostal muscles relax
•Ribcage pulled up and out
•Diaphragm muscles contracts –flattens/pulls
down
•Increase in thoracic cavity volume, lowers
pressure, thus drawing in air

41. Expiration
•External intercostal muscles relax
•Internal intercostal muscles contract
•Diaphragm relaxes –moves up
•Ribcage moves down and in
•Thoracic cavity volume decreases
•Pleural fluid is non compressible and assists
in forcing out air due to increased pressure

42. Control of Breathing
Respiratory centre
Chemoreceptor
pCO
2
LowpH

43. Effects of gas concentration on
breathing rate
•When pO
2decrease and pCO
2increases, the
rate and depth of breathing increases
•When pO
2increases and pCO
2decreases,
the rate and depth of breathing decreases

44. Importance of Partial pressure of CO
2
pCO
2 increase
Detected by chemoreceptor
Impulse to respiratory centre
Impulse to intercostal and diaphragm muscle by
efferent nerve
Rate and depth of breathing increase pCO
2
back to normal
Feedback

45. GAS COMPOSITION IN BREATHING
GAS INHALED (%)EXHALED (%)
NITROGEN 78 78
OXYGEN 21 16
CARBON
DIOXIDE
0.04 4