Tag: evolutionary changes in heart

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Multiple choice evolutionary changes in heart transportation - the circulatory system

Four chambered heart is present in 

  1. Frog

  2. Crocodile

  3. Shark

  4. Lizard
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Among reptiles the heart is 3- chambered but the crocodile is an exception where the heart is 4- chambered but not completely divided. The left and right aorta are connected by a hole called the foramen of Panizza. The frog heart has 3 chambers: two atria and a single ventricle. Sharks have a two-chambered heart, with an atrium (also called the auricle) and a ventricle. Lizard also has three chambered heart. 
Thus, the correct answer is option B.
Multiple choice evolutionary changes in heart transportation - the circulatory system

The number of chambers in the heart of fish are

  1. One

  2. Two

  3. Three

  4. Four
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Fish heart is made up of 2 chambers- one auricle and one ventricle, The auricle receives the deoxygenated blood which then passes to ventricle and then to whole of the body. 
Therefore, the correct answer is option B.
Multiple choice evolutionary changes in heart transportation - the circulatory system

Papillary muscles are located in

  1. Ventricle of rabbit

  2. Dermis of mammalian skin

  3. Orbit of vertebrate eyes

  4. Pylorus of vertebrate stomach
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The muscles present in the ventricles of heart and get attached to atrioventricular valves via chordae tendinae are known as papillary muscles. Their contraction prevents the inversion of theses valves on systole. 
Multiple choice evolutionary changes in heart transportation - the circulatory system

Why four-chambered heart is beneficial?

  1. It increases blood pressure.

  2. It pumps blood to the lungs more often, so blood is better oxygenated.

  3. It separates oxygenated and deoxygenated blood.

  4. It lowers blood pressure and the threat of heart attacks.

  5. It supplies the brain with more blood for cognition.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the case of four-chambered heart, there are two atria and two ventricles. The type of blood circulation in such type of heart is called as double circulation, including pulmonary and systemic circulation. The blood enters twice through the heart in this cycle, which prevents the deoxygenated and the oxygenated blood from getting mixed and the circulation is maintained properly. 

Thus, the correct answer is option 'It separates oxygenated and deoxygenated blood'.

Multiple choice evolutionary changes in heart transportation - the circulatory system

Which animal has most mixing of oxygenated and deoxygenated blood in the ventricles?

  1. Scoliodon

  2. Rabbit

  3. Frog

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In fishes (e.g., Scoliodon) the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned to the heart (single circulation).
In amphibians (e.g., Frog) and reptiles, the left atrium receives oxygenated blood from the gills/lungs/skin and the right atrium gets the deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood (incomplete double circulation).
In birds and mammals (e.g., Rabbit), oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The ventricles pump it out without any mixing up, i.e., two separate circulatory pathways are present in these organisms, hence, these animals have double circulation.

Multiple choice evolutionary changes in heart transportation - the circulatory system

Heart of elephant is

  1. Neurogenic

  2. Myogenic

  3. Loop of Henle

  4. Bowman's capsule
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The heart of an elephant is myogenic, as all the vertebrates have myogenic hearts. Myogenic contraction refers to a contraction initiated by the myocyte cell itself instead of an outside occurrence or stimulus such as nerve innervation. For most insects, heart contraction is initiated and regulated predominantly by external nerves; thus, insect hearts are neurogenic. In contrast, vertebrates, tunicates, and some molluscs have myogenic hearts. The heart beat is initiated and regulated by specialized groups of muscle cells.

Multiple choice evolutionary changes in heart transportation - the circulatory system

Starling's law of heart

  1. Greater the stroke volume, greater is the heart rate

  2. Greater the initial length of cardiac muscle fibre, more is the force of contraction of heart

  3. Lesser the length of cardiac muscle fibre, greater the force of contraction

  4. Greater the minute volume, greater is the heart rate.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Starling's law states that the force of ventricular contraction is directly proportional to the initial length (end-diastolic volume) of the cardiac muscle fibers.

Multiple choice evolutionary changes in heart transportation - the circulatory system

The last structure to be reached by a tracer substance injected into a patient's superior vena cava before leaving heart is

  1. Right ventricle

  2. Left ventricle

  3. Pulmonary veins

  4. Left atrium

  5. Right atrium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pathway of the blood in the heart occurs in the following manner:

Vena Cava
Right Atrium
Right Ventricle
Pulmonary artery
Lungs
Pulmonary Vein
Left Atrium
Left Ventricle
Aorta
Body organs.
So, The blood actually leaves the heart after the left ventricle. If any tracers substance is injected into a patient's superior vena cava, it shall visit all the chambers and the last chamber to be visited before it finally leaves the heart will be left ventricle.
Hence, the correct answer is 'Left Ventricle'.

Multiple choice evolutionary changes in heart transportation - the circulatory system

Carotid labyrinth in frog is present on

  1. Brain

  2. Pulmocutaneous trunks

  3. Carotid artery

  4. Index finger of frog
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The amphibian carotid labyrinth is a characteristic maze-like vascular expansion at the bifurcation of the common carotid artery into the internal and external carotid arteries. 

So, the correct option is 'Carotid artery'.

Multiple choice evolutionary changes in heart transportation - the circulatory system

Which of the following vertebrates were the first to evolve a three chambered heart for proper distribution of oxygen in the body?

  1. Fishes

  2. Reptiles

  3. Amphibians

  4. Birds

  5. Mammals
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
A. Fishes have two-chambered heart having one auricle and one ventricle.
B. Reptiles have three-chambered heart having two auricles and one ventricle.
C. Amphibians have three-chambered heart having two auricles and one ventricle.
D. Birds have four-chambered heart having two auricles and two ventricles.
E. Mammals have four-chambered heart having two auricles and two ventricles.
Hence, the amphibians were the first to evolve a three-chambered heart for proper distribution of oxygen in the body.
So, the correct answer is 'Amphibians'.