Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IB Biology HL > Option D6 Gas Transport > Flashcards

Option D6 Gas Transport Flashcards

1
Q

Type 1 and Type 2 Pneumocytes

A
  • Type I pneumocytes are very thin in order to mediate gas exchange with the bloodstream (via diffusion)
  • Type II pneumocytes secrete a pulmonary surfactant in order to reduce the surface tension within the alveoli
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Capillaries

A
  • The capillaries are located close to the pneumocytes and are composed of a very thin, single-layer endothelium
  • The capillaries transport oxygen within red blood cells, while white blood cells may extravasate into the lung tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Haemoglobin

A

composed of four polypeptide chains, each with an iron-containing heme group that reversibly binds oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

O2 molecule binds to haemoglobin

A
  • This means haemoglobin will have a higher affinity for O2 in oxygen-rich areas (like the lung), promoting oxygen loading
  • Conversely, haemoglobin will have a lower affinity for O2 in oxygen-starved areas (like muscles), promoting oxygen unloading
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Oxygen dissociation curve

A

show the relationship between oxygen levels (as partial pressure) and haemoglobin saturation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Adult haemoglobin

A
  • The oxygen dissociation curve for adult haemoglobin is sigmoidal (i.e. S-shaped) due to cooperative binding
  • There is a low saturation of haemoglobin when oxygen levels are low (haemoglobin releases O2 in hypoxic tissues)
  • There is a high saturation of haemoglobin when oxygen levels are high (haemoglobin binds O2 in oxygen-rich tissues)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Fetal haemoglobin

A
  • The haemoglobin of the fetus has a slightly different molecular composition to adult haemoglobin
  • Consequently, it has a higher affinity for oxygen (dissociation curve is shifted to the left)
  • This is important as it means fetal haemoglobin will load oxygen when adult haemoglobin is unloading it (i.e. in the placenta)
  • Following birth, fetal haemoglobin is almost completely replaced by adult haemoglobin (~ 6 months post-natally)
  • Fetal haemoglobin production can be pharmacologically induced in adults to treat diseases such as sickle cell anaemia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Myoglobin

A
  • Myoglobin is an oxygen-binding molecule that is found in skeletal muscle tissue
  • It is made of a single polypeptide with only one heme group and hence is not capable of cooperative binding
  • Consequently, the oxygen dissociation curve for myoglobin is not sigmoidal (it is logarithmic)
  • Myoglobin has a higher affinity for oxygen than adult haemoglobin and becomes saturated at lower oxygen levels
  • Myoglobin will hold onto its oxygen supply until levels in the muscles are very low (e.g. during intense physical activity)
  • The delayed release of oxygen helps to slow the onset of anaerobic respiration and lactic acid formation during exercise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Three mechanisms where carbon dioxide is transported between lungs and tissues

A
  • Some is bound to haemoglobin to form HbCO2 (carbon dioxide binds to the globin and so doesn’t compete with O2 binding)
  • A very small fraction gets dissolved in water and is carried in solution (~5% – carbon dioxide dissolves poorly in water)
  • The majority (~75%) diffuses into the erythrocyte and gets converted into carbonic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Transport as Carbonic Acid

A
  • When CO2 enters the erythrocyte, it combines with water to form carbonic acid (reaction catalysed by carbonic anhydrase)
  • The carbonic acid (H2CO3) then dissociates to form hydrogen ions (H+) and bicarbonate (HCO3–)
  • Bicarbonate is pumped out of the cell in exchange with chloride ions (exchange ensures the erythrocyte remains uncharged)
  • The bicarbonate in the blood plasma combines with sodium to form sodium bicarbonate (NaHCO3), which travels to the lungs
  • The hydrogen ions within the erythrocyte make the environment less alkaline, causing haemoglobin to release its oxygen
  • The haemoglobin absorbs the H+ ions and acts as a buffer to maintain the intracellular pH
  • When the red blood cell reaches the lungs, bicarbonate is pumped back into the cell and the entire process is reversed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Carbonic acid

A

Aqueous carbon dioxide can combine with water in the blood plasma to form carbonic acid.

  • Carbonic acid may then lose protons (H+) to form bicarbonate (HCO3–) or carbonate (CO32–)
  • The released hydrogen ions will function to lower the pH of the solution, making the blood plasma less alkaline
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Chemoreceptors in balancing blood pH

A

Chemoreceptors are sensitive to changes in blood pH, and can trigger body responses in order to maintain a balance:

  • Lungs regulate the amount of carbon dioxide in the bloodstream by changing the rate of ventilation
  • Kidneys control the reabsorption of bicarbonate ions from the filtrate and clear any excess in the urine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Blood pH

A

A narrow tolerance range of 7.35 to 7.45 to avoid the onset of disease.
- Maintained by plasma proteins that act as buffers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Buffering solution

A

Resists changes to pH by removing excess H+ ions (increasing acidity) or OH- ions (increasing alkalinity).

  • Amino acids are zwitterions, meaning they have positive and negative charges, and are able to buffer pH changes
  • Amine groups in amino acids can take on H+ ions
  • Carboxyl group in amino acids can release H+ ions (forms water with OH- ions)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Oxyhemoglobin dissociation curve

A

Demonstrates the saturation of hemoglobin by oxygen under normal conditions.
- pH changes alter the affinity of hemoglobin for oxygen, consequently altering the uptake and release of oxygen of hemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Bohr effect

A

A decrease in pH shifts the oxygen dissociation curve to the right.

  • Carbon dioxide lowers blood pH by forming carbonic acid, causing hemoglobin to release oxygen
  • Cells with increased metabolism (ex. respiring tissues) release larger amounts of carbon dioxide, resulting in the promotion of hemoglobin to release oxygen
17
Q

Respiratory control center

A

Located in the medulla oblongata, it responds to stimuli from chemoreceptors in order to control ventilation.

  • Central chemoreceptors (medulla oblongata): detect changes in carbon dioxide levels
  • Peripheral chemoreceptors (carotid and aortic bodies): detect carbon dioxide and oxygen levels as well as blood pH
18
Q

Respiratory control center during exercise

A

Metabolism increases during exercise, resulting in a buildup of carbon dioxide and a reduction in the supply of oxygen.

  • Changes are detected by chemoreceptors and impulses are sent to the respiratory control center
  • Signals are sent to the diaphragm and intercostal muscles to increase the rate of ventilation (involuntary)
  • As ventilation rate increases, carbon dioxide levels in the blood drop and oxygen levels to rise, restoring blood pH
  • Long term effects: improved vital capacity
19
Q

Partial pressure

A

The pressure exerted by a single type of gas when found within a mixture of gases.
- Determined by the concentration of gases within the mixture and total pressure of the mixture

20
Q

Respiration at high altitudes

A

Lower air pressure and lower partial pressure of oxygen causes difficulty for hemoglobin to uptake and transport oxygen.
- Respiring tissues consequently receive less oxygen, leading to symptoms such as fatigue, headaches, and a rapid pulse

21
Q

Acclimatization to high altitudes

A
  • RBC production will increase in order to maximize oxygen uptake and transport
  • RBCs will have a higher hemoglobin count with a higher affinity for oxygen
  • Vital capacity will increase to improve rate of gas exchange
  • Muscles will produce more myoglobin and have increased vascularization to improve overall oxygen supply
  • Kidneys will begin to secrete alkaline urine (improves buffering of blood pH)
  • People living permanently at high altitudes will have a greater lung surface area and larger chest sizes
  • Athletes can incorporate high altitude training to adopt benefits prior to competition
22
Q

Emphysema

A

A lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls.

  • Loss of elasticity results in the abnormal enlargement of alveoli, leading to lower surface areas for gas exchange
  • Degradation of alveolar walls can cause holes to develop, merging alveoli into big air sacs (pulmonary bullae)
23
Q

Causes of emphysema

A
  • Smoking (chemical irritants damage lung tissue and produce the enzyme elastase, which breaks down elastic fibers in the alveolar wall)
  • Hereditary deficiency in the elastase inhibitor (small proportion)
24
Q

Treatments for emphysema

A

Currently no cure, but treatments can relieve symptoms and delay progression.

  • Changes in lifestyle (stop smoking!)
  • Bronchodilators: relax bronchiolar muscles and improve airflow
  • Corticosteroids: reduce inflammatory responses
  • Elastase activity can be blocked by an enzyme inhibitor if concentrations are not overly high
  • Oxygen supplementation: ensures adequate oxygen intake
  • Surgery and alternative medicines
25
Q

Asthma

A

A common chronic inflammation of the airways to the lungs.

  • Inflammation leads to swelling and mucus production, resulting in reduced airflow and bronchospasm
  • During an acute attack, constriction of the bronchi smooth muscle may cause significant airflow obstruction
  • Common symptoms: shortness of breath, chest tightness, wheezing, and coughing
  • Severe cases may be life-threatening if left untreated
26
Q

Environmental triggers for asthma

A

Mnemonic: ASS FACE

  • Allergens (ex. pollen)
  • Smoke/scented products
  • Stress and anxiety
  • Food preservatives and certain medications
  • Arthropods (ex. dust mites)
  • Cold air
  • Exercise
27
Q

Lung cancer

A

Describes the uncontrolled proliferation of lung cells, leading to the abnormal growth of lung tissue (tumor).

  • Abnormal growth can impact normal tissue function, leading to a variety of symptoms according to size
  • Tumors can remain in place (benign) or spread to other regions of the body (malignant)
  • One of the most common causes of cancer-related deaths worldwide
  • Likelihood of cancer spreading is high because lungs possess a rich blood supply
28
Q

Symptoms of lung cancer

A
  • Coughing up blood
  • Wheezing
  • Respiratory distress
  • Weight loss
  • If pressed up to adjacent organs, it can cause chest pain, difficulty in swallowing, and heart complications
29
Q

Causes of lung cancer

A
  • Smoking
  • Radiation
  • Aging
  • Pollution
  • Infections
  • Genetic predispositions

IB Biology HL (32 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions