Circulatory system under human system comprises of veins, arteries, heart dealing with blood flow in human body. It is an important system for entrance applicants of Medical, para-medical and applied science students.
Video Note
Human heart is myogenic, frog’s heat is neurogenic. The wall of heart consist of pericardium, myocardium and endocardium (outside to inside).
Area of chest overlying the heart is called pericardium.
Coronary sulcus divides heart into right auricle larger than left auricle.
In right auricle 2 venecava in man and 3 venecava in rabbit open.
During embroynic stages in place of inter-atrial or inter-auricular septum, septum primum and septum secondum are present having a gap called foramen ovalis.
A flap called Eustachian flap is present from the opening of inferior venecava up to foramen ovalies which prevent the entry of blood in the fetal heart to lungs.
During birth there is closure of foramen ovalis but thre remains depression on both sides, depression on right atrium is fossa ovalis and on left is fossa lunata.
Right auricle-ventricle- tricuspid valve
Left auricle-ventricle- bicuspid valve
Semilunar valve controls backflow of blood from aorta and pulmonary artery
Wall of ventricles have muscular bundles called columnae cornea or papillary muscle. Bicuspid and tricuspid valves are attached to papillary muscle through cordae tendinae.(absent in frog, prevent backflow of blood from valve)
Moderator band present in right ventricle.
Ear like appendages attached to atria is auricle.
At places of crossing the pulmonary aorta and caroticosystemic aorta are connected by muscular band known as ligamentum arterosum which during embryonic stages was represented as ductus arteriosum or duct of botalli.
Sinus venosus (dorsal side of frog) and trunchus arteriosus (obliquely upon ventral surface of right atrium in frog) are accessory chambers in heart of lower vertebrates (fishes and amphibians)
In rabbit sinus venosus is formed in embryo but later becomes of right atrium.
Cardiac centre is medulla oblongata
Impulse originated in SA node--------------->Wall of auricle-------------------> auricle contracts --------->AV nodes- sends impulses --------->Bundle of his- Right & Left bundle branch --------------->Purkinje fibers --------------->Wall of ventricles-------------> ventricle contracts
Cardiac cycle in human = 0.8 sec
In frog = 0.94 sec
Heart sound: 1st lubb, 2nd dub
Athletes have low heart rate ( Bradycardia)
Pulmonary vein, Inernal jugular vein, Sinuses of brain and Superior venecava are the veins without valve.
Renal portal system present in frog and human hepatic portal system in human
First branch of aorta is coronary artery and first branch of arch of aorta is Brachiocephalic artery.
Umbilical cord has two artery and one vein. Albumin synthesized by liver.
Cistern chili/ receptaculum chili- second heart present below diaphragm and collect lymph from posterior part of body.
Phrenic artery supply blood to diaphgram.
Anterior abdominal vein ( formed by union of right and left pelvic vein) present in frog is absent in rabbit and mammal.
Diaphragm penetration T8 – Venecava
T10- Oesophagus
T12- Thoracic Duct Aorta
Frog heart beat – 64 per minute
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zoology video