Chapter 9: Gas Exchange and Smoking Flashcards
features of human gas exchange system
- link circulatory system with atmosphere
- cleans and warms air thats breathed in
- maximises surface area for diffusion of O2 & CO2 between blood and atmosphere (alveoli increase it)
- minimise distance for diffusion
- maintain adequate gradients for this diffusion
process of gas exchange in unicellular organisms:
simple diffusion of o2 from environment through cell membrane to cytoplasm
collective surface area of alveoli in lumps ie _ is _
ie total gas exchange surface =70m2
capacity if thoracic cavity
5dm3 or 5l
air passage
nose, trachea, bronchus, terminal bronchiole, respiratory bronchiole, alveolus
function of C shaped cartilage in trachea
- keep it open
- maintain air resistance ie low
- prevent collapsing/bursting as air pressure goes high/low respectively
bronchus has what instead of C shaped cartilages to serve the same function
irregular blocks of cartilage
what encloses gas exchnage system
throacic cavity
pleural membrane …
covers lung, fluid between pleural membrane space allows friction free movement as lungs are ventilated
bronchiole walls have and dont have :
smooth muscles that contract/relax to adjust diameter of airways. dont have cartilage
which 2 are sites of gas exchnage
alveolar duct and alveoli
which have cilia
trac,bron, tbron and rbron few
which have smooth muscle
trac,bron, tbron
which have cilia and goblet cells
trachea and bronchi
approx no and diameter of trachea
1, 1.8cm
approx no and diameter of bronchus
2, 1.2cm
approx no and diameter of t bronchiole
48000, 1mm
approx no and diameter of r bronchiole
300,000, 0.5mm
approx no and diameter of alveolar duct
9*10
significance of cartilage in trachea and bronchus
keeps airways open and air resistance low and prevents from collapsing as air pressure changes during breathing
significance of thoracic cavity
its closed cavity bordered by diaphragm at base and ribs having intercostal muscles in between at sides. helps in supporting and maintenance of pressure inside throracic cavity to support inspiration/expiration
why are bronchioles made up of smooth muscles and not cartilage
these can contract and relax to adjust diameter of tiny airways. during excercise muscles relax to allow greater flow of air to alveoli, absense of cartilage makes these adjustments possible
function of goblet cells
secrete glycoprotein called mucin or mucus needed to trap dust, virus, bacteria, or other foreign substances
adaptation of goblet cells
folds/villi increase surface area for secretion
organelles important in gobs
nucleus, er, golgi, vesicles
pathway of air in detail ie regarding warming, wbc, mucus etc
as air flows into nose and trachea it is warmed to body temp and moistened by evapo from lining so protecting delicate surfaces inside lungs from dessication (drying out).
particles larger than 5-10Mm caught on hairs in nose and mucus lining nasal passages and etc.
phagocytic wbc ie macrophages patrol surfaces of airways scavenging for small particles like dust and bact. during an infection they join other phagocytic cells which leave capils to help remove pathogens.
when mucus reaches top of trachea its swallowed so pathogens are destoryed by stomach acid or coughed out of the respiratory tract
6 membranes of alveolus through which diffusion happens? (use your mnemonic)
- Fluid and Surfactant Layers lining the alveolus
- Alveolar Epithelium
- Epithelial Basement Membrane
- Interstitial space
- Capillary Basement Membrane
- Capillary Endothelium
alveoli responsible for
creating a gas exchange interface/surface
how do alveoli “contract/relax”
alveolar walls contain elastic fibres of elastin which stretch during insp and recoil during exp to help force air out
why is elasticity important in alveoli
allow them to expand according to volume of air breathed in.
elastics, alveoli and breathing during excercise…
alveoli fully expand according to volume of air breathed in, they hence increase surface area for diffusion. air is expelled efficiently when fibres recoil
alveoli walls are _, made of _ layer of _ cells of diameter _
thin
single
squamous epithelial
0.5Mm thick
blood capillaries close to alveoli walls are thin, _ cell thick made of _
single
endothelial
why are o2 and co2 able to diffuse between air and blood quickly
small distance
o2 transportation during circulation
breathing brings air to lungs with relatively high o2 conc. blood is brought to lungs with lower o2 conc. and higher co2 conc. than air in alveoli. both gases diffuse down the gradients in opposite directions
tobacco smoke streams
main 15%
side is 85%, is a form of passive smoking and has most toxic ingredient
cig smoke constituents and the body system the affect
tar - gas exchange
carcinogens - gas exchange
nicotine- cardiovascular
CO- cardiovascular
another name for lung cancer ie full form of COPD
chronic obstructive pulmonary diseases
what are COPDs
group of lung diseases that block airflow and cause breathing difficulties
COPDs include (2)
chronic bronchitis and emphysema
what is chronic bronchitis
inflammation of bronchi tube which carry air to and from lungs
mechanism of CB
- tar in cig smoke stimulates goblet cells and mucus glands, and mucus produced in large amounts accumulates and blocks bronchioles
- tar in cig smoke destroy cilia and weaken sweeping action of ciliated epithelium, resulting in failure of mucus loaded dirt, bact, virus etc, and this collects and blocks bronchioles
as CB progresses it results in
- infection in lung due to mucus loaded with foreign particles, lining becomes inflamed, blocking bronchioles
- damaged ciliated epithelium replaced by scar tissue hence smooth muscles lining bronchioles get thicker, bronchiole narrows
symptoms of CB
- severe cough accompanied by phlegm production ie = WBC +mucus+ bacteria
- infection such as pneumonia easily developed
mechanism of emphysema
-inflammation of infected lung leads to movement of phagocytes from blood to airways to reach lining of airways.
-these wbc need to digest elastin fibres, achieved by secretion on elastase by them which makes pathway to airways.
-digestion hampers expansion and recoiling of alveoli
bronchioles collapse during expiration, trapping air in alveoli
-then either air remains in lung, not ventilated and rapid breathing rate
-or alveoli bursts and gas exchange surface reduces
elastin fiber function
expansion and recoiling of alveolus
as emphysema progresses …
blood vessel becomes resistant to blood flow. to compensate for increased resistance blood pressure in pulmonary artery increases, right side of heart enlarges
symptoms on emphysema
- breathlessness
- wheezing
- right heart enlarges
- very small particles, less than 2Mm diameter can reach alveolus eg allergin, bacteria
difference between sign and symptom
sign: visible expression of disease to doctor
symptom: felt and reported by patient
7 steps of lung cancer
- tar in tobacco smoke has carcinogens
- these react directly or via breakdown product to DNA of epithelial cells lining respiratory pathway
- mutation in DNA of epithelial cells
- uncontrolled division, benign tumor forms
- tumor supplied with blood & lymph vessels. cells spread
- metastasis. tumor cells invade other tissues, secondary cancers form
- malignant tumor
diagnosis of cancer
- bronchoscopy (endoscope to see bronchi lining)
- chest x ray
- ct scan
treatment of cancer
- surgery
- radiation therapy
- chemotherapy
4 effects of nicotine
- produces adrenaline (hormone) which increases heart rate and blood pressure
- constricts arterioles (vasoconstriction) hence there’s less bloody supply to body extremes i.e. hands/feet
- stimulates reward centers (nervous system) of brain by stimulating release of dopamine =pleasure
- increases risk of blood clotting
why is CO bad
- binds with haemoglobin of rbc to make carboxyhaemoglobin
- Hb has 250* more affinity to CO than O2. hence O2 carrying capacity of blood reduced
- less O2 transported to heart via coronary arteries
- CO damages wall of arteries that leads to buildup of fatty tissue
diseases which are a result of blockage of blood flow to heart via coronary arteries by fatty tissue
Coronary heart disease
stroke
heart attack
coronary artery bypass surgery:
done to improve blood flow to heart muscle
involves using piece of blood vessel from elsewhere in body to create a bypass around blocked portion or coronary artery
