respiratory system

3 types of respirations

1. ventilation → movement of air and out of resp. passages in lunges

2. gas exchange —>

   1. diffusion of O2 and CO2 thru capillaries in lungs

   2. O2 and CO2 transport to and from body cells

   3. diffusion of O2 and CO2 between blood and body cells

3. cell respiration —> constantly aerobic for catabolic processes to make ATP and Co2

properties of gas-exchange surface (5)

1. area of cell membrane → larger = greater exchange of O2 and CO2

2. respiratory surface must be kept moist → its covered by film of moisture for diffusion to occur (CO2 and O2 must be in solution)

3. thin → diffusion distance must be small - mostly single layer of cells

4. permeable → O2 and CO2 can diffuse freely

5. concentration difference between O2 and CO2

pathway of air

1. nostrils

2. nasal passages/nasal cavity

3. pharynx [passageway for food + air connects with trachea + esophagus]

4. larynx (vocal cords)

5. treachea

6. thoracic cavity

7. two bronchi

8. terminal bronchioles

9. alveolis

what structures in noses are important for its respiratory functions (3.5)

• tiny hairs (cilia) → stop dust and foreign particles from entering

• walls are lined with muscous membranes → moisten air/trap partiles

• large # of capillaries → warm the air

  • warming helps protect delicate tissues of lungs

what is a part of the larynx that is crucial (3)

• vocal cords (elastic ligaments) held by cartilaginous materal

• air causes vocal cords to vibrate - sound

• epiglottis prevents chocking

what is the important structures and functions of trachea (2.5)

• supported by semi-circular rings - prevent trachea from collapsing and food to esophagus

• passages of upper respiratory tract lined with ciliated mucous membrane - traps foreign membrane

  • continual movement of cilia propels material back into nose + throat to be expeleld by coughing or sneezing

bronchi structures/division (3.5)

• divides into 2 bronchi

• 1 bronchus enters each lung and bifurcates (divides) into bronchioles

  • no cartilage and cluster of alveolies

• composed of cartilage and ciliated mucous cells

lungs (right 3, left 2) 5.5

• nerves + dense network of blood-filled pulmonary capillaries

• each lung surrounded by pleural membrane

  • seals lungs in thethoracic cavity from rest of body

• inner layer ADHERES firmly to surface

• thin film of fluid sealed between 2 layers of pleura and holds together in breathing

• is pleural layers seal is broken and air gets in, lungs dont adhere and lung collapses

function and structure of alveoli (3.5)

• lungs have 300 million alveolis → HUGE SA for gas exchange

  • 70 m² → 40x the SA of skin

• spherical shape → larger SA

• single layer very thin cells epithelium

structures and functions type 1 penumocytes- AT1 (4)

• very small and thin (0.15 um diametter) since adapted for gas exchange

• surrounded by many pulmonary capillaries diffuse very short distance less than 0.5 um away) → increase rate of gas exchange

• passive transprot (due concentration gradient)

• AT1 have very little cytoplasm, mitochondria and other organelles

structure and function type II - pneumocytes AT2 (5.5)

• SO MANY (90%) of these rounded cells that onyl take up 5% of alveolar SA

• secrete fluid to keep inner surface moist - gasse sdissolve

• thicker than AT1 - 10um diameter - dense cytoplasm, more mitochondira, rER/RER and lysosomes

• many phospholipids synthsized in cytoplasm and stored in lamellar bodies} - secreted by exocytosis

  • they form a single layer on outer surface of film mositure - hydrophilic haeds facing water and tails air of alveolus

• proteins secreted by lamellar bodies are dispered between phospholipid molecules

• layer acts as a surfactant to reduce surfance tnesions and prevents sides of alveoli from sticking together when air exhaled

what other types of cells are in lungs (not pneuomocytes)

• some contain collagen fibres - strengthen lung tissue

• elastic fibres limit inhlaation and cause passive exhalation

boyles law

• decreasing volume of gas → more collisions between gas molecules

• higher # of collisions increases with pressure

what is the pressure of a single gas?

• partial pressrue

• gases move from aresas of higher pressure to areas of lower pressure

combination of two structures in rib cage

1. pump handle - lifts up away from pump (ribs moving UP and AWAY from spine )

2. bucket handle - lift away from the sides of the bucket (ribs moving outward LATERALLY)

• both braodens the rib cage in all directions

muslces of diaphragm and intercoastal muscles

• diaphragm is a muscle layer separating thoracic cavity from abdominal cavity

• intercoastal muscles - associated with ventral surface of rib cage

what happens sudinrg inspiration/inhalation (5.5)

• the diaphragm contracts downwards + flattens → enlargement of thoracic cavity and pushes abdomen wal out

  • muscles in abdomen relax

• the external intercostal muscles contract - ribs upwards and outwards - away from body

• internal intercostal muscles relax - pull back into their elognated state

• increase in volume of thoracic cavity → decrease in air pressure within space (air has more space to move)

• pressure OUTside lungs is much greater than pressure of of air WITHIN lungs

  • due to partial pressure laws

percent values of inhaling O2 and CO2 vs exhaltion concentration

inhalation

• O2 = 21 %

• CO2 = 0.04%

exhalation

• O2 = 16%

• CO2 =3-5%

both inhale + exhale of N2 and trace gases = 79%

expiration (5.5)

• the diaphragm relaxes - pushed up into domed shaped

• muscles in abdomen wall contract - organs + diaphragm pushed up

• external intercostal muscles relax - go back to elongated state

• internal intercostal muscles relax - ribs go down and in

• contractions cause volume of thoracic cavity to decrease

  • air pressure in lungs increases and greather than outside

  • air rushes OUT due to partial pressure differences between 2 spaces

tidal volume (TV)

• volume of fresh air normal unforced breathing cycle/ventilation (# of times that air is inspired or expried per minute)

inspiratory reserve volume (IRV)

• max volume of air inspired FORCEFULLY from end of tidal inspiration

  • deep breath

expiratory reserve volume (ERV)

• max volume of air that can be expired foreccfully beyond end of tidal expiration

  • exhale forcefully

residual volume (RV)

• volume of air remains in lungs and passageways even after maximum expiration

• never leaves respiratory system - lungs would collapse

  • little value for gas exchange

vital capacity (VC)

• max volume of air that can be expired after max inspiration

TV + IRV + ERV = VC

every min - 5-7L air moved in and out

what are the 4 feedback controls of ventailation rate

1. respiratory stimuli- change in arterial pressure of CO2/arterial pressure of O2, change in blood pH, change in lung partial pressure of O2

2. respiratory receptors - chemo (chemical factors) or baroreceptors (alveolar)

3. respiratory centres - located in brain stem

4. respiratory effectors

   1. normal inspiration.expiration → diaphragm + external intercostals muscles

   2. forced expiration → internal intercostals muscles + abdominal muscles

types of respiration control

• voluntary respiration → people control (hold breath, speaking, singing)

• involuntary respiration - controlled by negative feedback regulator

central vs peripheral chemoreceptors (4)

how does feedback loops react for O2 and CO2 in chemoreceptors

• if too little O2 in arterial blood - breathing increases (O2 decreases)

• if CO2 of cells exceeds rate exhaled, ventilation increases to match rate

CO2 and ventilation rate

• after CO2 enters bloodstream and in blood → lower portion of brain

• CO2 combines with water to form carbonic acid - dissociate H+ and bicarbonate ions

• H+ stimulat central C.R.

• lowered pH → acidosis (levels below 6.8)

• a good level is 7.35-7.45 pH

• greater rolle controlling rate of breathing than O2

what do chemoreflexes do

• protect asphyxia (CO2 build up) and hypoxia (lack of O2 in tissues)

• hypoxia → “silent killer”