Types of heart

Animal physiology-Types of heart

1. TYPES OF HEART AMRUTHA K H II MSc ZOOLOGY

2. Heart is a muscular organ Pumps blood through blood vessels In humans, heart is located between the lungs Divided into 4 chambers- upper left and right atria, lower left and right ventricle Right atria and ventricle-right heart Left atria and ventricle-left heart

3. Enclosed in a protective sac- pericardium,contain small amount of fluid Wall of heart is made up of 3 layers- epicardium,myocardium & endocardium

4. 6 types :- Chambered Heart Tubular Heart Ampullar Heart Lymph Heart Neurogenic Heart Myogenic Heart

5. Chambered Heart Closed circulatory system found in vertebrates and cephalopods Vertebrate heart-2 or 3 or 4 chambered In fish, heart-auricle and ventricle Amphibian heart-2 auricle and ventricle Reptiles-incompletely 4 chambered Molluscan -either 1 or 2 auricle and 1 ventricle

6. FISH HEART

7. Auricle-thin walled Ventricle- thick walled contractile structure

8. Tubular Heart Seen within arthropods Exist as contractile heart Single chamber with reinforced walls with striated muscles Valves prevent backflow of blood Ascidians-heart pumps, gradually stops and reverses direction

9. Sea squirts

10. Ampullar Heart Accessory heart-common occurrence in insect Met at different places in insects body Brachial heart comes under this category Activity depends on specialized extrinsic muscles Seen in cephalopods,crusteceans

11. Lymph Heart Animals that pump lymph Seen in lungfish,reptiles,flightless birds Function as small pump Lymphatic system of frog contains- lymph,lymph vessels, lymph heart, lymph spaces Mast cells is also found Lymph heart-rhythmically and slowly pumps

12. Toad-normal lymph heart rate is 50 beats per minute Frogs and toad have 10 to 20 lymph heart Caecilians have more than 100 lymph heart Reptiles-single pair of lymph heart

13. Neurogenic Heart Animals with open circulatory system-heart is sac-like Has ostia ,gets closed when heart contracts and open when relaxes Known as suction pump Beating rhythm is set through nerve impluse - neurogenic heart

14. Requires nervous input to contract Crustacean cardiac ganglion-cluster of neurons-produce rhythmic motor output Seen in annelids, insects

15. Myogenic Heart Rhythmic power reside in heart muscle Muscle fiber in blood plasma-shows rhythmic contraction In chick and fish embryos heart beat even before it had any connections with nervous elements Teleosts-floor of atrium and artio-ventriclular function usually contain pacemaker cell

16. Found in invertebrates like molluscs Heart beat originate ant any point over the heart In limulus, pacemaker is large ganglion mass 2 chains of nerve cells occur on heart of cockroach-probably the pacemaker