more CV

Question 1

Describe the positioning of the heart in the dog

Answer 1

o Left chambers sit caudally
o Right chambers sit cranially
o Base sits dorsally and cranially to apex (tilted forward)
o Apex sits caudally and dorsal to base and slightly to left

Question 2

DEscribe the gross anatomy of the dogs lungs

Answer 2

 Right lung  4 lobes (each supplied by one airway) – cranial, middle, caudal, and accessory on ventral aspect.
 Left Lung has 2 lobes – cranial and caudal. Cranial lobe subdivided into cranial/caudal part of cranial lobe.
 Hard to see in pigs due to marbling effect
 Horses lack a middle lobe on right lung

Question 3

Describe and explain the route blood takes through the heart

Answer 3

 LA receives O blood from lungs via pulmonary vein, through to LV: atrioventricular (MITRAL) valve. Delivers to rest of body via aorta. RA receives DO blood from rest of body via vena cava, through to RV through right atrioventricular (TRICUSPID) valve. Delivers to lungs via pulm artery.
 Left and right separated by interatrial septum, LRV by interventricular septum

Question 4

When listening to the heart what is between beats

Answer 4

DIASTOLE

Question 5

What is characteristic of the sound of diastole

Answer 5

1. much longer than systole as needs time for filling phase = shouldn’t hear anything

Question 6

What is a heart murmur caused by

Answer 6

generated by turbulence in the blood caused by anything in the blood caused by anything which disturbs laminar flow

Question 7

Is there is a long gap between heart beats is this diastole or systole murmur

Answer 7

SYSTOLIC

Question 8

Describe the structure and function of the valves

Answer 8

i.All 4 are supported on outside by annulus fibrosis, a fibrous skeleton which also serves as an electrical insulation between A and V
 Supported in inside (free edge) by chordae tendinae which attach to free edge of valve and run down to projections of muscles in ventricles called papillary muscles
 Papillary muscles (muscular projections on ventricular wall) attached to chordae tendinae (fibrous muscles) hold AV valves in place, anchoring and prevent prolapse
 Chordae prevent cusps entering atrium during ventricular systole

 RAV (Tricuspid) has 3 cusps in most species but 2 in dogs main with several small commissural cusps at the free edge
 LAV (mitral/ bicuspid) 2 main
ii. Semilunar: prevent arterial blood flowing back into ventricles in diastole
 Made up of 3 semilunar shaped cusps
 Because of shape = already supported so don’t need chordae tendionae and pepillary muscles.
> Function: ensure blood flows in correct direction  open and close to prevent back flow