Question

how is carbondioxide transported from tissues to the lungs​

Answer 1

Answer:

$\huge{\green{\bold{\underline{\underline{\overline{\overline{\pink{the\: Answer:-}}}}}}}}$

Explanation:

Carbon dioxide is transported in the blood from the tissue to the lungs in three ways:1 (i) dissolved in solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly haemoglobin. Approximately 75% of carbon dioxide is transport in the red blood cell and 25% in the plasma.

Answer 2

Answer: Carbon dioxide is produced by cell metabolism

in the mitochondria. The amount produced

depends on the rate of metabolism and the relative amounts of carbohydrate, fat and protein

metabolized.The amountis about 200mlmin1

when at rest and eating a mixed diet; this utilises

80% of the oxygen consumed, giving a respiratory quotient of 0.8 (respiratory quotient ¼

rate of carbon dioxide production divided by

rate of oxygen consumption). A carbohydrate

diet gives a quotient of 1 and a fat diet 0.7.

Carbon dioxide transport in

the blood

Carbon dioxide is transported in the blood

from the tissue to the lungs in three ways:1

(i) dissolved in solution; (ii) buffered with

water as carbonic acid; (iii) bound to proteins,

particularly haemoglobin.

Approximately 75% of carbon dioxide is

transport in the red blood cell and 25% in the

plasma. The relatively small amount in plasma

is attributable to a lack of carbonic anhydrase

in plasma so association with water is slow;

plasma plays little role in buffering and combination with plasma proteins is poor.

There is a difference between the percentage

of the total carbon dioxide carried in each

form and the percentage exhaled from them.

For example, 5% of the total is in solution but

10% of exhaled carbon dioxide comes from this

source; 10% is protein bound, particularly with

haemoglobin, but this supplies 30% of the

exhaled amount.

Dissolved carbon dioxide

Carbon dioxide is 20 times more soluble than

oxygen; it obeys Henry’s law, which states that

the number of molecules in solution is proportional to the partial pressure at the liquid

surface. The carbon dioxide solubility coefficient is 0.0308 mmol litre–1 mm Hg–1 or

0.231 mmol litre–1 kPa–1 at 37C. (Solubility

increases as the temperature falls.) This corresponds to 0.5 ml kPa–1 carbon dioxide in 100 ml

blood at 37C. The partial pressure of carbon

dioxide is 5.3 pKa in arterial blood and 6.1 kPa

in mixed venous blood; therefore, arterial

blood will contain about 2.5 ml per 100 ml

of dissolved carbon dioxide and venous

blood 3 ml per 100 ml. A cardiac output of

Carbonic acid

Carbon dioxide combines with water to form

carbonic acid, a reaction accelerated by carbonic anhydrase. The carbonic acid then freely

dissociates (Equation 1).

CO2 þ H2O Ð

carbonic anhydrase

H2CO3

Ð Hþ þ HCO

3 ð1Þ

The enzyme carbonic anhydrase is present

in a number of organs of the body including

the eye, kidney and brain; however, for this

purpose, it is the red blood cell carbonic anhydrase that is important. Once carbonic acid is

formed it dissociates easily so that the ratio of

Carbon dioxide and water diffuse freely

into the red blood cell and are converted to

carbonic acid, which dissociates into hydrogen

and bicarbonate ions. Hydrogen ions do not

pass through cell membranes but carbon

dioxide passes readily. This situation cannot

be sustained as the intracellular hydrogen ion

and bicarbonate ion concentration, osmolarity

and cell size will rise and rupture the cell. Thebicarbonate ion diffuses out to the plasma to be exchanged for

chloride ions. This is known as the chloride shift (Gibbs–Donnan

equilibrium or Hamburger effect). An ion exchange transporter

protein in the cell membrane called Band 3 for Cl–

HCO3

– facilitates

chloride shift.

A build up of hydrogen ion in the red blood cell would also

prevent further conversion and production of bicarbonate ion.

However, hydrogen ions bind easily to reduced haemoglobin,

which is made available when oxygen is released; therefore, free

hydrogen ions are removed from solution. Reduced haemoglobin

is less acidic than oxygenated haemoglobin. This is another way

of stating the Haldane effect, which explains that, at any given

PCO2, the carbon dioxide content of deoxygenated blood is

greater than that of oxygenated blood.

As a result of the shift of chloride ions into the red cell and the

buffering of hydrogen ions onto reduced haemoglobin, the intercellular osmolarity increases slightly and water enters causing

the cell to swell. This can be measured as an increase in mean

corpuscular volume (MCV). The reverse process occurs as the

red blood cell passes through the lung.

Bound to haemoglobin and other proteins

Carbon dioxide combines rapidly to the terminal uncharged

amino groups (R-NH2) to form carbamino compounds.

.........................plz mark my answer as brainlist