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Human Breathing Nose Air can be taken in through the mouth (buccal cavity) or the nose.

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Presentation on theme: "Human Breathing Nose Air can be taken in through the mouth (buccal cavity) or the nose."— Presentation transcript:

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2 Human Breathing

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4 Nose

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14 Air can be taken in through the mouth (buccal cavity) or the nose.

15 The nose: Breathing in through the nose is beneficial because:

16 The nose: Breathing in through the nose is beneficial because: (1) The air is filtered by the hairs and the mucous in the nose.

17 The nose: Breathing in through the nose is beneficial because: (1) The air is filtered by the hairs and the mucous in the nose. (2) It is moistened.

18 The nose: Breathing in through the nose is beneficial because: (1) The air is filtered by the hairs and the mucous in the nose. (2) It is moistened. (3) It is warmed as it passes across the nasal passages.

19 These 3 things make it easier for the air to diffuse from the lungs into the bloodstream.

20  Warm, moist air diffuses easier!!

21 The pharynx:

22 Pharynx is the part of the throat that begins from behind the nose to the beginning of the voice box and the oesophagus.

23 It is a common channel that both air and food pass through. Because of these two functions, the pharynx must open to allow air and food to pass through.

24 Epiglottis: Because of the need to swallow and breathe there is a flap of tissue called the epiglottis which closes off the trachea when your swallowing and closes off the oesophagus when breathing.

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26  Thererfore when breathing this prevents food and drink entering the trachea (windpipe).

27 Larynx:

28  The vibrations produce sound which our tongue and lips convert to speech.  Contains two vocal cords.  These vibrate when we force air across them.

29 Area of the windpipe containing the larynx is called the glottis.

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31 Trachea:  The trachea, bronchi and bronchioles are all made of muscle and elastic fibres and incomplete rings of cartilage.  Rings of cartilage prevents tubes from collapsing as air is drawn in.

32 Trachea  bronchi  bronchioles.  Bronchioles become narrow during an asthma attack.

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35 Cilia:  Sticky.  Beat  create an upward current.  Moves the mucus into the oesophagus  to the stomach.  Clearing our throats  force mucus up and away from the vocal cords.

36  All of these air pipes are lined with mucous secreting cells and tiny hairs called cilia.

37  These trap particles such as dust, bacteria and viruses.

38 Lungs:  Large spongy structures.  Where gaseous exchange takes place.  Each lung is surrounded by the pleural membrane.  The outer pleura lines the chest wall and diaphragm.  The inner pleura lines the lungs.

39  T T T The gap between these 2 membranes is the pleural cavity and it is full of liquid. TTTThis liquid lubricates the membranes and reduces friction during breathing.

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41 Alveoli:  Each bronchus divides into about a million bronchioles.  These end in hollow, balloon-like air sacs called alveoli (or alveolus).  700 million alveoli in the 2 lungs.  Very large surface area for gas exchange = tennis court

42  Each alveolus is 1 cell thick.  Moist.  Enclosed in a network of blood cappilaries (like the villi).  When the gases are exchanged they only have to pass through the alveoli membrane and the capillary wall.

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44 Function of the alveoli: Gas exchange.

45 Gas exchange: Respiration happens in cells to supply energy. Respiration happens in cells to supply energy.  Body cells use up oxygen and produce carbon dioxide and water. Eqn: C6H12O6 + 6O2 ---  6CO2 + 6H2O + energy. Eqn: C6H12O6 + 6O2 ---  6CO2 + 6H2O + energy. Enzymes

46 Gaseous exchange = diffusion!!!  C C C CO2 and H2O diffuse out of cells and into the blood because the cytoplasm has a high conc of CO2 and H2O compared with the blood.  I I I In the lungs, CO2 and H2O diffuse out of the blood into the alveoli  from ↑ conc to ↓ conc.

47  Diffusion is: the movement from a high conc to a low conc.  In the same way, O2 diffuses from the alveoli into the blood and then from the blood into body cells.  Exhalation: body cells  CO2  plasma (in blood)  alveolus  exhale.  Inhalation: O2 from air  alveolus  blood  body cells.

48 Transport of gases: (1). O2 is mostly carried by haemoglobin (97%) + 3% carried in the plasma. (2). CO2 is dissolved in plasma and carried in blood. H2O is carried in plasma.

49 Inhaled v’s Exhaled air:

50 Mechanism of breathing:  Normally involuntary.  At rest: 15 times per minute.  In: inhalation/inspiration.  Out: exhalation/expiration.

51 The process:  Medulla oblongata in the brain controls the rate of breathing.  It sends a message to the diaphragm and intercostal muscles.  Muscles contract = active process.

52 Inhalation. (1) Ribs pull up and out/ Diaphragm moves down.  Pressure in the chest cavity falls.  Internal air pressure is now higher than the pressure of air in the chest.  Air is forced into the lungs = inhalation.

53 Exhalation. (2) Intercostal muscles and diaphragm relax.  Ribs move down and in/ Diaphragm moves up.  The volume of the chest cavity decreasesd.  Thoracic pressure increases.  Air is forced out = exhalation.

54 Note: Note:  Exhalation  Exhalation is said to be passive because the muscles only have to relax. Nervous control is not needed.

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56 Effect of exercise on the rate of breathing:  Respiration is using food to make energy.  Therefore, exercise ↑ the rate of respiration, esp in muscle cells ( ↑ energy is needed so respiration ↑ ).  During exercise:  The medulla oblongata detects the ↑ level of exercise and therefore ↑ the rate of breathing.  Exhalation is normally passive  becomes active during exercise.  Extra muscles are used to ↑ the depth of breathing.

57 Asthma. BBBBreathing disorder. SSSSymptoms: -Narrowing of the bronchioles in the lungs. AAAAppearance: -Noisy, wheezy breathing and a feeling of breathlessness.

58 Cause:  Not  Not clear.  May  May be triggered by inhaled allergens. -pollen. -animal dander. -dust and dust mites. -lung infections. -exercise. -stress. -anxiety.

59 Incidence:  10% of children.  Incidence is rising in developed countries.  Around half of children affected grow out of it.

60 Prevention:  Identifying and avoiding those allergens.  Tests can be taken to identify the allergens.

61 Treatment:  Inhalers:  Drugs that widen the bronchioles to make it easier to breathe.  Injection:  In severe cases.

62 Control of breathing:  Respiratory centres in the medulla oblongata.  Monitor levels of CO2 in the blood and tissue fluid.  CO2 is slightly acidic  it causes the pH to drop slightly.

63  These respiratory centres detect this drop and react by sending out impulses to the diaphragm and intercostal muscles to help us breathe.  Exercise increases CO2 in blood.

64 We breathe in response to high CO2 not low O2!


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