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Physiology (Term 2) > Respiration 1 > Flashcards

Respiration 1 Flashcards

1
Q

What is cellular respiration?

A

Intracellular- mitochondrial

uses O2 and produces CO2 and energy.

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2
Q

What is external respiration?

A

Gas exchange (O2 in and CO2 out) between the external environment and the cells.

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3
Q

What are the 4 steps to external respiration?

A
  1. Ventilation or gas exchange between the atmosphere and air sacs (alveoli) in the lungs
  2. Exchange of O2 and CO2 between air in the alveoli and the blood in the pulmonary capillaries
  3. Transport of O2 and CO2 by the blood between the lungs and the tissues
  4. Exchange of O2 and CO2 between the blood in the systemic capillaries and the tissue cells
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4
Q

Describe the main properties of lungs

What do we need for effective external respiration?

A

properties:

  • A 75m2 sheet of single- and multiple-layer epithelial cells (Surface area)
  • Can fit into 3 litres (Volume)
  • High SA:VOL

what the lungs need:

  • Connect it to the outside
  • Keep it hydrated
  • Structures protect it from inhaled damage (muscociliary escalator) and external trauma (ribcage)
  • Control how it operates

(controlled by autonomic nervous system and skeletal muscles)

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5
Q

Non-respiratory functions: defend and maintain

A
  • Alveolar macrophages and the mucociliary escalator►defence against inhaled particles
  • Inspired air must be warmed and humidified ► lungs are a route for water loss and heat elimination
  • Pressure differential in the chest vein ►enhances venous return
  • Pulmonary ventilation rate responds to H+ (via CO2) in the blood ►helps maintain normal acid–base balance by increaseing ventilation which brings in more O2 and takes away excess CO2
  • Control of the vocal cords in respiratory tract►enables speech, singing, and other vocalisation
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6
Q

What are the airway’s defences?

A
  • The bronchi help to defend the airways►Bronchial epithelial cells produce anti-microbial peptides
  • The mucociliary escalator lines the bronchi and it consists of:
  • Goblet cells which produce sticky mucus to trap bacteria
  • Ciliated epithelial cells which beat the mucus to the pharynx
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7
Q

Cilia beating generate the

A

mucociliary escalator:

Cell surface- epithelial cells which line the bronhi protruding from it are cilia

Fluid in this environment that allows cilia to move backwards and forward

Directly above are goblet cells which produce sticky mucus (glycoproteins)

Allows bacteria, viruses, pollen and dust be be trapped

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8
Q

What is the mucociliary escalator made of?

A

Sticky mucus, made of glycoproteins, traps inhaled particles and bacteria

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9
Q

Describe the mucociliary escalator

A

Cilia project into the periciliary fluid- a liquid layer secreted by epithelial cells

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10
Q

What does the action of the ciliary beating do?

A

The action of the cilia beating then moves the mucus raft to the back of the throat

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11
Q

What action is taken by the mucociliary escalator when you inhale things like bacteria or dust?

A
  1. Epithelial cells increase fluid secretion (pericilliary fluid)
  2. Goblet cells produce mucus
  3. bacteria/dust gets stuck
  4. This can either be ingested (cilia beat the material down into the stomach to be destroyed by stomach acid) or cilia move it up and you spit it out
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12
Q

What does healthy airway epithelium look like?

A
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13
Q

What does CF airway epithelium look like?

A

Individuals do not secure enough fluid to keep the muscus flowing.

Genetic mutation- issues with chloride pump disrupts osmotic balance so mucus does not have enough water

Mucus (consists of glycoproteins) builds up and aggregates (purple area in the diagram)

Allows bacteria to proliferate leading to fatal lung infections

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14
Q

Why is smoking bad for your lungs?

Compare the alveoli in a smokers lung compared to that of a non smokers lung

A
  • Cigarette smoke paralyses the cilia (for up to 4 hours)
  • Mucus hypersecretion blocks the airways
  • Alveolar macrophages can’t defend you
  • Lungs are irreversibly damaged
  • In a healthy persons lung the alveoli are separated by a thin wall which allows efficient transfer of oxygen to their neighbours
  • The alveoli in a smokers lung appears larger and have large borders between them gas exchange becomes immensely restricted
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15
Q

What does the respiratory system consist of?

A

the airways, lungs and muscles

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16
Q

What are the structures that comprise the airways?

A

–Pharynx and Larynx

–Trachea

–Primary bronchi

— Nasal cavities

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17
Q

Does gas exchange occur in the airways?

A

NO

The lungs are responsible for gas exchange

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18
Q

What structures are resposible for gas exchange?

A

–Respiratory bronchioles

–Alveolar ducts

–Alveolar sacs

–Alveoli

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19
Q

How do muscles contribute to gas exchange?

A

Responsible for moving air in and out of the airways and lungs

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20
Q

What are the main muscles involved in gas exchanhge?

A

Mucles of the abdomen are very important for gas exchange

21
Q

Does branching increase surface area?

What is the structure from the upper to lower part of respiratory tract?

A

yes

From upper to lower part of respiratory tract:

structures become smaller: (trachea►bronchi►bronchioles►terminal brochioles►respiratory bronchioles►alveolar ducts►alveolar sacs

surface area to volume ratio increases

22
Q

Explain the properties of alveoli and how they are important to their function

A
  • Alveoli are thin-walled, inflatable air sacs encircled by pulmonary capillaries.
  • Alveoli are the units of gas exchange.
  • Alveoli walls consist of a single layer of flattened Type I (90%) alveolar cells (pneumocytes).
  • Type II (5%) alveolar cells secrete pulmonary surfactant.
  • Alveolar macrophages are found in the lumen.

approx 300 million alveoli in each lung

23
Q

Describe the functional features of alveloli?

A
  • Large space in the middle (alveolus) which allows gas exchange
  • Capillaries and blood vessels surrounding it
  • Monocytes which mature into macrophage to eat any nasty material inhaled
24
Q

What are alveoli surrounded by?

A

An almost continuous sheet of blood maximises gas exchange to get the oxygen to metabolically active tissue cells

25
Q

How do we breathe?

Explain respiratory mechanics for getting air into the lungs

A
  • Lungs cannot expand by themselves, they need to respond to external pressures
  • To get air into the lung we need to create a positive pressure to PUSH air in (artificial ventilation)
  • Or create a negative pressure within the lungs to allow air to FLOW in
26
Q

What does Boyles law tell us about the lungs?

A

It tells us how air gets into the lungs

27
Q

What does Boyles law state?

What does this mean?

A
  • Boyle’s law states that pressure is inversely proportional to volume
  • Air flows down a pressure gradient- from higher to lower pressure.
  • Boyle’s law means that as you breathe in, the volume of your lungs increases, so pressure decreases, allowing air to flow in to the lungs
28
Q

What are the requirements of Boyle’s law?

A
  1. structure which is able to change volume (elastic tissue)
  2. walls that do not collapse (supported structure)
  3. mechanism to modify volume of thoracic cavity (musculature)
29
Q

What muscles are important for breathing?

A
  1. Diaphragm (flatened sheet of muscle-pulls down when you breathe in to increase the size of your thoracic cavity)
  2. Intercostals (between the ribs:

internal which moves the rib cage down and in and external contract and pull your rib cage up and out which increases the volume of the thoracic cavity and decreases the pressure)

3.Accessory muscles (Facilitate higher activity e.g. exercise)

30
Q

Important structures in the process of breathing: Pleura

A

surrounds the lungs which reduces friction or damage to the lungs analagous with the pericardial sac surrounding the heart

Annology denoted by the diagram: Dipping a lollipop into a water filled balloon

31
Q

What does parietal pleura line?

A

the thoracic cavity

32
Q

Where is visceral pleura found?

A

It covers the lungs

33
Q

What is the function of the pleural space?

Where is it found?

A
  • The pleural space is in between the parietal and the visceral pleura.
  • It is a fluid lining that reduces friction
34
Q

Describe the Transmural Pressure Gradient

A

mediated by pleural sac

  • Insures that Intrapleural pressure (756mmHg) < atmospheric pressure (760mmHg)
  • Stretched lungs pull away from the larger thoracic wall, expands the pleural cavity and drops intrapleural pressure below atmospheric pressure

allows lungs to always be partially inflated

35
Q

What does the TPG (transmural pressure gradient) prevent?

A
  • prevents lung collapose
  • Traumatic pneumothorax (hole in the lung) means that pressure on either side would equate
  • Pleural fusion (excess inflamation in the lungs causes a lot of fluid retention- also causes lungs to collapse)
36
Q

Describe the breathing cycle

A

–Air alternately flows into and out of the lungs due to cyclic changes in intra-alveolar pressure

–Onset of inspiration: contraction of inspiratory muscles after impulse recieved from CNS and reaches the diaphram

–Role of accessory inspiratory muscles (in fight or flight responses)

–Onset of expiration: relaxation of inspiratory muscles

–Forced expiration: contraction of expiratory muscles (during extreme bouts of exercise or fight/flight response)

37
Q

Inspiration: Passive expansion of alveoli

A
  • Alveoli cannot expand by themselves
  • They respond passively to increased pressure across the alveolar wall
  • Muscles of inspiration contracting causes intrapleural pressure to drop – stretches lungs
  • Alveolar volume increase = alveolar pressure decrease (Boyle’s law)
  • Air flows INTO alveoli to equalise pressure differential
38
Q

Describe the process of Inspiration:

A
  1. before diaphragm is relaxed
  2. inspiration
  3. active contraction of muscles
  4. diaphragm up and out
  5. volume increases pressure decrases
  6. expiration (relaxation of the muscles) which is passive
39
Q

Inspiration: Expansion of the thoracic cavity

A
  • Chest wall stretches
  • Lungs expand
  • Increased volume = decreased pressure
  • Intrapleural pressure more negative
  • Transmural pressure difference increases
  • Air flows IN
40
Q

Forces at the end of expiration

A
  • Inward elastic recoil of alveoli is balanced by outward recoil of chest wall
  • No airflow
  • No air flow; atmospheric pressure=alveolar pressure
41
Q

Is expiration always passive?

A

NO

It is mostly passive but sometimes can be active

42
Q

What are the three pressure considerations?

A

–atmospheric pressure, 760 mm Hg at sea level

–intra-alveolar pressure (intrapulmonary pressure), varies with ventilation

–intrapleural pressure (intrathoracic pressure), normally less than atmospheric

43
Q

Give a summary of the respiratory system

A
  1. The respiratory system comprises conducting airways, the lungs (alveoli) and the respiratory muscles
  2. The main function of the respiratory tract is to enable gas exchange (ventilation) for cellular respiration
  3. The respiratory tract also protects (alveolar macrophages)
  4. It’s all about pressure gradients
  5. Inspiration is active: increase volume, decrease pressure
  6. Expiration is passive: decrease volume, increase pressure
44
Q

What are the protective structures and mechanisms of the lungs?

A
  • mucociliary escaclator
  • macrophages
  • pleural sac
45
Q

What is atmospheric pressure at sea level?

A

760mmHg

46
Q

What is TPG mediated by?

A

Pleural sac

47
Q

What structures keep the trachea open?

A

Cartilagionous rings that keep the trachea open

48
Q

Why is intrapleural pressure always negative?

A

Because the pressure inside the the pleura is balanced on the dynamic harmonious antagonism between the chest wall which wants to expand and the elastic lung which tends to recoil

Physiology (Term 2) (24 decks)

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