SELECT * FROM question_mgmt as q WHERE id=552 AND status=1 SELECT id,question_no,question,chapter FROM question_mgmt as q WHERE courseId=2 AND subId=7 AND chapterId=21 and ex_no='1' AND status=1 ORDER BY CAST(question_no AS UNSIGNED) CBSE Free NCERT Solution of 11th biology Body Fluids and Circulation describe the evolutionary change in the pattern of

Question: Describe the evolutionary change in the pattern of heart among the vertebrates.

Answer:

All vertebrates possess a heart – a hollow muscular organ composed of cardiac muscle fibres. The function of the heart is to pump oxygen to all parts of the body. The evolution of the heart is based on the separation of oxygenated blood from deoxygenated blood for efficient oxygen transport.

In fishes, the heart was like a hollow tube. This evolved into the four-chambered heart in mammals.

Piscean heart
Fish has only two chambers in its heart – one auricle and one ventricle. Since both the auricle and the ventricle remain undivided, only deoxygenated blood passes through it. The deoxygenated blood enters the gills for oxygenation from the ventricle. It has additional chambers such as sinus venosus and conus arteriosus.

Piscean heart 

 

 

 

 

 

 

 Amphibian heart

Amphibians, such as frogs, have three-chambered hearts, with two auricles and one ventricle. The auricle is divided into a right and a left chamber by an inter-auricular septum, while the ventricle remains undivided.
Additional chambers such as sinus venosus and conus arteriosus are also present. The oxygenated blood from the lungs enters the left auricle and simultaneously, the deoxygenated blood from the body enters the right auricle. Both these auricles empty into the ventricle, wherein the oxygenated and deoxygenated blood get mixed to some extent.

Amphibian heart 

 

 

 

 

 

 

Reptilian heart

Reptiles have incomplete four-chambered hearts, except for crocodiles, alligators, and gharials. They have only one accessory chamber called sinus venosus. The reptilian heart also shows mixed blood circulation.

Reptilian heart 

 

 

 

 

 

 

 Avian and mammalian hearts

They have two pairs of chambers for separating oxygenated and deoxygenated bloods. The heart is divided into four chambers. The upper two chambers are called atria and the lower two chambers are called ventricles. The chambers are separated by a muscular wall that prevents the mixing of the blood rich in oxygen with the blood rich in carbon dioxide.

Avian and mammalian hearts


< Previous Question

Next Question >

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='2' AND subId='7' AND ex_no!=0 AND status=1 and id!=552 ORDER BY views desc, last_viewed_on desc limit 0,10

  • Popular questions of class 11 Biology

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='2' AND subId='7' AND ex_no!=0 AND status=1 and id!=552 ORDER BY last_viewed_on desc limit 0,10

  • Recently Viewed Questions of Class 11 Biology

Comments

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

Comment(s) on this Question


NCERT Solutions

Quick Links

Resources

Support