Anatomy of Bloodflow Through Heart 1

Question 1

describe the bloodflow through pulmonary and systemic and hepatic portal circulations

Answer 1

1. right atrium receives deoxygenated blood from systemic circulation (cranial and caudal vena cava)
2. directed to right ventricle (tricuspid valve)
3. exits pulmonary trunk –> pulmonary arteries to lungs through the pulmonary valve
4. left atrium to the left ventricle (mitral valve) and exit via aorta (aortic valve)
5. arterial blood to the head, neck and forelimbs via subclavian and common carotid arteries
6. arterial blood to body tissues via descending and abdominal aorta –> hepatic portal system in liver
7. venous returns to right atrium via cranial and caudal vena cava

Question 2

where is the heart within the thorax in left lateral view

Answer 2

between ribs 3-6 at an angle with its base lying cranial and dorsal to the apex which lies caudal and ventral

Question 3

what is the position of heart in dorsoventral view

Answer 3

lies to the left of midline

apical heart beat

Question 4

what is the cardiac notch

Answer 4

the region of the heart which is in direct contact with the body wall

the heart is sitting surrounded by mediastinal pleura –> passing over the lateral surfaces of the heart and holding it here between the left and right thorax

Question 5

where is the heart relative to the mediastinum

Answer 5

within its own serious sac (pericardium) within the middle mediastinum

Question 6

what are the structures of the middle mediastinum

Answer 6

Question 7

what structure covers the heart

Answer 7

pericardium

tough structure –> fibrous material (not much flexibility, can cause problems if fluid build up or heart enlarges)

Question 8

what are the structures of the pericardium

Answer 8

divided into visceral and parietal layers

vsiceral layer –> adherent to surface to heart and reflects over great vessels and then adheres to the fibrious layer that is between the mediastinum

pericardium is filled with fluid –> between parietal and visceral layer (continuous with outersurface of the heart –> epicardium) –> serous fluid fills this gap

Question 9

what are the layers of the heart

Answer 9

1. epicardium (outer)
2. myocardium (middle)
3. endocardium (inner)

Question 10

what is the epicardium layer composed of

Answer 10

1. superficial layer (visceral pericardium)
2. deeper fibroelastic CT

Question 11

what is the myocardium layer composed of

Answer 11

1. cardiac muscle
2. endomysium CT

Question 12

what is the endocardium layer composed of

Answer 12

1. endothelium and CT
2. purkinje fibres

Question 13

what type of epithelium is the endocardium

Answer 13

simple squamous epithelium

Question 14

how is cardiac muscle arranged

Answer 14

in circular and spiral arrangement of cardiac muscle bundles in the myocardium

networks to ensure proper directional flow when they contract and squeeze the blood through the different chambers of the heart

Question 15

identify the histological features of the cardiac muscle

Answer 15

Question 16

list 5 histological features of the cardiac muscle

Answer 16

1. striated muscle with centrally located nuclei
2. branching myofibres
3. purkinje fibres
4. intercalated discs (connections between myofibres that allow for unified contraction of sarcomeres)
5. endomysium (CT running between the myofibres)

Question 17

what view of the heart is this and why

Answer 17

right lateral view

1. between apex and base –> coronary groove (1/3 down), fat filled that forms a band around the heart
2. right inter-ventricular groove is seen (separates the entire ventricular mass into two)
3. cranial and caudal vena cava coming into the right atrium

Question 18

identify the base and apex

identify the coronary groove

identify right inter-ventricular (subsinuosal) groove

identify major blood vessels entering the right atrium

Answer 18

1. coronary groove –> usually fat filled and contains coronary blood vessle
2. right inter-ventricular groove –> contains coronary blood vessels (defines position of right and left ventricles, cranial and caudal margins of the heart are defined)
3. major blood vessels entering right atrium –> caudal vena cava, cranial vena cava and right azygous vein

Question 19

identify the view of the heart and the structures

Answer 19

right lateral

1. right atrium
2. caudal vena cava
3. aorta
4. right azygous vein (opening into the cranial vena cava)

Question 20

identify which view of the heart this is

Answer 20

left lateral view (auricular surface)

Question 21

can you see 1 or more auricles (blind ending sacs associated with each atrium)

identify the coronary groove

identify the left inter-ventricular groove or paraconal groove

identify the ventricle that forms the apex

identify where the aorta arises from

Answer 21

1. coronary groove (fat filled) –> interrupted on the left side by a large blood vessel (pulmonary trunk)
2. left inter-ventricular groove or paraconal groove –> cranial margin = right ventricle, caudal margin = left ventricle
3. left ventricle forms the apex
4. aorta arises from middle of base, medial to pulmonary trunk and to the left of the esophagus

Question 22

identify the view shown and the structures

Answer 22

left view of heart

1. left auricle
2. pulmonary trunk
3. right ventricle
4. left ventricle
5. left azygous vein

Question 23

what view of the heart is this

Answer 23

right view

Question 24

what view of the heart is this

Answer 24

left

Question 25

identify the structures and the view of the heart shown

Answer 25

right lateral

Question 26

identify the view and the structures

Answer 26

left lateral view

Question 27

what are the structures

Answer 27

1. right atrium 1'. right auricle 2. right ventricle 3. right atrioventricular valve 4. caudal vena cava 5. intervenous tubercle 6. cranial vena cava 7. terminal crest 8. fossa ovalis

Question 28

how does venous return from systemic circulation enter the heart

Answer 28

**blood entering right atrium** from: 1. cranial vena cava and caudal vena cava (intervenous tubercule separates flow) 2. azygous vein --\> venous return lumbar region (also l. azygous vein in ruminants and pigs) 3. coronary sinus: venous return coronary circulation

Question 29

what separates the flow of the cranial and caudal vena cava

Answer 29

intervenous tubercule

Question 30

identify the structures

Answer 30

**coronary sinus**: sitting on top of atrial ventricular septum --\> where venous return of coronary vessels

Question 31

identify the structures of the right atrium and auricle (blood flow)

Answer 31

left arrow: caudal vena cava and coronary sinus x: interveouns tubercule top right: azygous vein and cranial vena cava

Question 32

list the main anatomical features of the interior of the right atrium (5)

Answer 32

1. thin walled, smooth lining 2. auricle --\> blind ending sac with pectinate muscles 3. inter-atrial septum --\> position of fossa ovalis --\> remnant of fetal circulation --\> foramen ovale 4. terminal crest --\> position of SA node; AV node at inter-ventricular septum 5. right AV valve or tricuspid valve (3 cusps)

Question 33

identify the structures of the interior of the right atrium

Answer 33

Question 34

what is the impulse conducting system of the heart

Answer 34

AV bundle within interventricular septum directs the impul se to the apex --\> trabecula septomarginalis --\> impuse to papillary muscles in preparation for ventricular contraction

Question 35

what are the structures

Answer 35

1. vagosympathetic trunk 2. sympathetic trunk 3. middle cervical ganglion 4. 4'. cranial and caudal limbs of ansa subclavia 5. vertebral node 6. cervicothoracic ganglion 7. communicating branches 8. 8'. caudodorsal and caudoventral cervicothoracic nodes 9. vertebral cardiac nodes 10. 10'. third and seventh thoracic ganglia 11. thoracic cardiac nodes 12. left recurrent laryngeal nodes 13. 13'. cranial and caudal vagal cardiac nodes

Question 36

what are the structures of the heart wall

Answer 36

**endocardium:** inner lining of heart, where blood is flowing over and will be continuous with blood vascular system want smooth and low friction --\> simple squamous epithelium (endothelium) **serous pericardium:** (visceral layer, epicardium) fatty material, fibrous CT and the visceral layer of the pericardium