Lungs

  • Created by: Hindleyc
  • Created on: 03-06-18 12:08
What are the lungs the site of?
Gas exchange
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Where are they located?
In the thorax
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What do they require?
Ventilation
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Which is smaller?
Left smaller than right- overlaps heart
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What is the ribcage?
Bony case enclosing lungs and heart
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How many?
12 pairs attached dorsally to vertebrate - top 10 pairs attached ventrally to sternum and remaining ribs floating
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What is connective tissue?
Supporting layer beneath epithelium made of fibres of collagen and elastin
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What are the blood vessels?
Capillary walls made of endothelial cells flattened forming narrow tubes with common basement membrane. Pores (fenestrations) between cells enable exchange. Extremely narrow so RBC's can squeeze through slowing down passage
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what does this do?
allows more time for diffusion, increases surface area of cell in contact with endothelium
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What do a network of capillaries from pulmonary artery unite to form?
Pulmonary vein
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What are the intercostal muscles between ribs responsible for?
movement
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What happens when the external contracts?
Ribs move up and out for inspiration
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What happens when the internal contract?
Ribs move down and in- expiration
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What is the diaphragm?
Muscular sheet that separates thorax from abdomen
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What are the Pleural membranes?
2 membranes that secrete pleural fluid- fluid filled cavity is lower than atmospheric pressure so prevents lungs deflating (air always enters)
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What does the trachea have rings of?
Cartilage to prevent the tube collapsing when internal pressure drops lined with ciliated epithelium
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What is the bronchi?
Trachea divides into 2 bronchi- these tubes enter each lung supported by cartilage
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What are the bronchioles?
branch throughout each lung and support from cartilage gradually decreases
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What is the alveoli?
Spherical sacs that are the major site of gas exchange- 100 micrometers diameter lined with flattened epithelial cells making vast area for exchange
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What is epithelial tissue?
Simple cells arranged in single or multilayered sheets covering internal and external body of an organism
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What do they often form in the body?
exchange surfaces with capillaries providing blood supply
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What is the first type of epithelium
flattened squamous surrounding alveolar wall with very thin diffusion pathway
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What is the second type?
Secrete surfactant mixture of lipids and proteins reducing surface tension and prevents alveoli collapsing and provides elastic recoil for lungs
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What are gas exchanged due to?
Concentration gradients
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What does oxygen do?
Diffuse into blood from alveolar air
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What does co2 do?
Diffuse into alveolar air from blood
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What is ficks law?
Rate of diffusion=SAxConc gradient/thickness of surface
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How is the surface area maintained?
Large due to alveoli and many small spherical sacs
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How is concentration gradient maintained through?
Pulmonary ventilation with circulation of blood
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How is thickness of surface minimised?
Single layer of squamous epithelium and single layer of endothelium
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What is pulmonary ventilation?
Breathing
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What do air movements occur due to?
Pressure differences between atmosphere and alveolar air
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What happens if intrapulmonary pressure is greater than atmospheric pressure?
Expiration
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What happens if atmospheric pressure is greater than intrapulmonary pressure?
Inspiration
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How are pressure differences achieved?
In thoracic cavity through action of intercostal muscles and positioning of diaphragm
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What surrounds each lung?
A pleural sac
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What is the outer and inner membrane attached to?
outer- ribcage inner-lungs
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what is the inner cavity pressure lower than? why?
Atmospheric pressure- prevents lungs deflating
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What happens when thorax moves?
Lungs do too
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What are alveoli?
Elastic and collapse if not held stretched by thorax
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What do they secrete?
Surfactant which prevents them sticking together
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What happens in inspiration?
Diaphragm contracts flattening and defending lengthening thorax cavity, external intercostal muscles contract pulling ribs up and out increasing diameter of throax increasing thorax volume- lungs expand decreasing pressure (alveolar) so inspiration
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What happens in expiration?
Diaphragm relaxes returning to domed portion shortening thorax cavity, internal intercostal muscles contract moving ribs down and in decreasing diameter of thorax decreasing thorax volume(elastic recoil of lungs) decreasing lung size
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then?
increasing intrapulmonary pressure so expiration
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What is forced inspiration/expiration?
When abdominal muscles are used greatly increasing intrapulmonary pressure such as blowing up a balloon or coughing
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What does a spirometer measure? what does it create
Volumes of air expired and inspired. spirogram
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What is it used to diagnose?
Ventilation deficiencies
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What is tidal volume?
Volume of air breathed in or out during quiet breathing/ at rest- around 500cm3 in adults
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What is breathing rate?
number of inspiration/expiration cycles in one minute/ per min
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What is pulmonary ventilation rate
tidal volume x breathing rate- volume of air breathed in or out per min during quiet breathing
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Other cards in this set

Card 2

Front

Where are they located?

Back

In the thorax

Card 3

Front

What do they require?

Back

Preview of the front of card 3

Card 4

Front

Which is smaller?

Back

Preview of the front of card 4

Card 5

Front

What is the ribcage?

Back

Preview of the front of card 5
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