GAS EXCHANGE AND SMOKING Flashcards
lungs:
where gas exchange occurs
they have a large surface area
trachea:
air enters the lung via the trachea
is lined with a smooth layer of c-shaped cartilage
is lined with a layer of ciliated epithelial cells and goblet cells
these trap bacteria and dust from inhaled air
bronchi:
the trachea divides into two tubes called bronchi
each bronchus leads to each lung
bronchi are also lined with cartilage
each bronchus divides into smaller tubes called bronchioles
bronchioles:
have alveoli where gas exchange takes place
alveoli:
air sacks that allow gas exchange
they have a layer of surfactant which is a phospholipid substance
without the surfactant, the watery lining of the alveolus would create a high surface tension during inhalation causing it to collapse
they have elastic fibers which allow the alveolus to expand during inhalation, increasing its surface area
what are the adaptations of the alveoli?
thin epithelial wall:
it is one cell thick which therefor makes the distance between blood and air short which means oxygen and carbon dioxide can be exchanged efficiently
large surface area:
which increases the rate of diffusion
surrounded by many capillaries:
which allows for gas exchange
how does gas exchange occur?
gas exchange takes place by diffusion down a concentration gradient
each alveolus is covered in capillaries
oxygen dissolves into the surfactant and diffuses from the air to the blood into haemoglobin in RBC’s
carbon dioxide diffuses from deoxygenated blood cells alveoli
what are the functions of cartilage?
trachea have a regular arrangement of C-shaped rings of cartilage
bronchi have irregular blocks of cartilage
both keep the airways open and prevent collapsing or burst as pressure changes when breathing
bronchioles don’t have cartilage to allow them to expand allowing more air to alveoli
what are the functions of goblet cells?
they are present in trachea and bronchi
they secrete mucus
mucus is a slimy solution of glycoproteins and carbohydrate chains making them sticky to trap inhaled particles like bacteria and dust
what are the functions of ciliated cells?
the continuous beating of their cilia sweeps mucus to the top of the trachea, away from the lungs
mucus can be spit or, if swallowed, pathogens in the mucus are destroyed by stomach acid
what are the effects of tar and carcinogens in tobacco on the gas exchange system?
tar settles on the lining of the airways inhibiting the action of cilia and stimulates goblet cells to secrete more mucus
this could lead to COPD (chronic obstructure pulmonary disease) and with carcinogens could cause lung cancer (bronchial carcinoma)
what are the short-term effects of nicotine on the cardiovascular system?
nicotine causes arterioles to constrict which reduces the blood supply to parts of the body like hands and feet reducing their supply of oxygen
it releases an adrenaline hormone which increases the heart rate and blood pressure which weakens the arterial walls
it increases the stickiness of blood platelets which increases the risk of blood clotting
what are the short-term effects of carbon monoxide on the cardiovascular system?
carbon monoxide combines with haemoglobin forming carboxyhaemoglobin which prevents the complete oxygenation of haemoglobin meaning that less oxygen is transported in the blood
it damages the walls of arteries
what are the three Chronic Obstructive Pulmonary Diseases?
chronic bronchitis
emphysema
lung cancer
what is chronic bronchitis?
tar stimulates goblet cells and mucus glands to secrete more mucus
it also destroys or weakens cilia
mucus, with dust and bacteria and viruses, accumulate in bronchioles, blocking them which stimulates smoker’s cough
with time, the walls of airways become thicker because it is damaged and replaced by scar tissue. this makes the airways narrow and difficult to move air in and out of the lungs
pathogens are trapped and multiply in the respiratory system causing inflammation and lung infections
