Dissection of to Show Circulatory Features

Dissection of to Show Circulatory Features

The following directions should assist you in locating the major arteries and veins in the cat. You should also consult Gilbert’s Pictorial Anatomy of the Cat during the dissections. For the page numbers, see the protocol A

natomy of the Circulatory System in the Cat.

HEART AND CHEST:

heart_cat_P4113363med

With the chest cavity open, split the parietal pericardium by snipping upward from the apex toward the base. Peel it back to reveal the heart. Note the superior vena cava is prominent in the mediastinal space above the heart and the inferior vena cava is below and behind the heart in a direct line with the superior vena cava.

heart_cat_P4113363crop

Note the atria (R & L) the ventricles and the anterior interventricular artery. Note the pulmonary trunk emerging diagonally up to your right from the R ventricle.
Here is a labeled view of the cat heart.

heart_transverse_P4083877
You may wish to make a transverse section through the upper portions of the ventricles of the heart. Illustrate this transverse section to show the R ventricle, interventricular septum and the L ventricle . Comment on the differences observed. If you do not do this procedure, observe and illustrate one on which it has been performed.

Veins_thorax_P4083871

Use the blunt probe to trace the branching of the superior vena cava to produce in succession the R & L innominate veins. These branch to form the jugular and the subclavian. The subclavian branches to form the subscapular and the axillary veins.
Here is a labeled picture of the veins of the thorax.

aortic_arch_P4083878
Behind the pulmonary artery, use the probe to find the aortic arch and its two branches (three in the human): the innominant artery (or brachiocephalic) and the left subclavian. Follow the innominant to its branches: L & R common carotids, and the R subclavian. Trace this latter to the R axillary, and then the R brachial artery.
Here is a labeled view of the aortic arch and the “Great Vessels.”

Circle_Willis_P4083870
The circle of Willis is formed from the two vertebral arteries below, which join to form the basilar artery. The basilar splits into the R & L posterior cerebral arteries. The internal carotids enter the cranium on either side of the sella turcica, and split to form the middle and anterior cerebral arteries. Posterior communicating arteries join the posterior and middle cerebral arteries, and the anterior communication artery joins the two anterior cerebral arteries. Here is a labeled version of the circle of Willis .

intercostal_P4083879

Roll the L lung medially and follow the descending aorta down along the rear wall of the thorax. Note the intercostal arteries running between the ribs under the parietal pleura.

ABDOMEN:

Celiac_Art_P4083866

Move the abdominal contents to the right, and find the rear border of the diaphragm. (It is lower in the rear than the front.) using the blunt probe, remove the peritoneum and adventitia to reveal the celiac and superior mesenteric arteries immediately below the diaphragm over the vertebral column. Find the three branches of the celiac artery: the hepatic to the cat’s R, the splenic (the large central vessel), and to the L, the left gastric
Here is a labeled version of the upper abdominal arteries.

abdominal_low_arts_P4083876
R & L Renal arteries and veins should be easily located. Note that the L gonadal vein drains into the L renal vein, while the R gonadal vein empties directly into the inferior vena cava . The R & L gonadal arteries branch off the descending aorta below the level of the kidneys. The last major branch from the abdominal aorta is the inferior mesenteric.

LOWER GROIN AND LEGS:

vessels_leg_P4083874

The descending aorta ends where it splits into the R & L common iliac arteries [“external” iliac in the cat]. These branch to form the deep femoral arteries (plunge deep just before abdominal wall) and the femoral arteries at the exit point from the abdomen. The saphenous vein, the major superficial vein of the leg, runs down the medial surface of the of the leg.

FEATURES TO IDENTIFY AND ILLUSTRATE IN THE CAT:
III. CIRCLE OF WILLIS
(underside of well-excised brain) (p. 82)
basilar artery
R&L posterior cerebral arteries
R&L posterior communicating arteries
R&L internal carotid arteries
R&L middle cerebral arteries
R&L anterior cerebral arteries
anterior communicating artery (difficult)

IV. THORAX, NECK AND ARMS
External features of the heart
(p. 62-63, 68-69)
pericardium
right atrium
right ventricle
left atrium (toward the rear)
pulmonary trunk
aorta

Vessels of the thorax, neck and arms (p. 62-63)
Veins:
superior vena cava (precava)
R&L innominate veins
R&L subclavian veins
axillary vein
brachial vein
R&L external jugular veins (p. 20)

Arteries: (p. 65, 69) (as in cat)
innominate artery
R&L common carotid
R subclavian artery
R axillary artery
R brachial artery
L subclavian artery
[esophagus]
descending aorta
intercostal arteries

V. ABDOMEN, GROIN AND LEG (p. 49-55)
Vessels of the abdomen:
(often under fat, close to vertebral column)
inferior vena cava
descending aorta
celiac artery (move abdominal contents to cat’s R)
L gastric artery
splenic artery
(common) hepatic artery
superior mesenteric artery
renal vein and artery
L gonadal vein:
empties into L renal vein
R gonadal vein:
empties into inferior vena cava
R&L gonadal arteries
inferior mesenteric artery

Lower groin and leg (p. 71)
external [common] iliac artery & vein
deep femoral artery (plunges just before abdml wall)
femoral artery & vein
saphenous vein

Histology of Circulatory System

Histology of Circulatory System

Examine the following slide, illustrate the specified view, label the specified features. Note the function of each type of blood cell.  Record the Vernier Scale addresses of each cell type.  The plate numbers are in di Fiore’s Atlas of Normal Histology, 9th Ed.  Histology of arteries and veins is at the bottom of this page.

Slide 1. Blood smear, human, 400x, VE: pp. 65, 67 (see also pp. 62-73.)

This slide has been stained with Wright’s stain, a complex stain containing eosin (a red stain) and methylene blue.  They allow differential staining of various leukocytes.
Illustrate in a single LARGE view: five or six erythrocytes and platelets, and then at least one each of each class of leukocyte. (Scan at 100x to find the rare leukocytes, then switch to 400x) Record the location of each cell type using the Vernier scale on the mechanical stage. Fill in addresses and copy in the form at bottom of page. Give function of each class (from text or lecture).

erythrocytes most numerous, featureless pink circles
platelets numerous, small, irregular shape and size, reddish (trigger clumping)

LEUKOCYTES:

AGRANULOCYTES

Class:
lymphocyte

Appearance
round nucleus, very little cytoplasm, smallest of leukocytes

Function
immune cells, either B cells or T cells

% total leukocytes
25 – 33%

vernier fore-aft _____________________

vernier lateral ______________________

Class
monocyte

Appearance
varied nuclear shape, “like a phone receiver” more cytoplasm, largest of leukocytes

Function
immature macrophage (part of the diffuse reticuloendothelial system of the body)

% total leukocytes
3 – 7%

vernier fore-aft _____________________

vernier lateral ______________________

GRANULOCYTES

Class
neutrophil

Appearance
numerous, pale cytoplasm, distinct multiple nuclear lobes also called polymorphonucleocytes = PMNs.

Function
major class of phagocytes, kill with H2O2, attract other phagocytes

% total leukocytes
57 – 67%

vernier fore-aft _____________________

vernier lateral ______________________

Class
eosinophil

Appearance
reddish granules in cytoplasm, nucleus bilobed

Function
phagocytose Ag-Ab complexes

% total leukocytes
1 – 3%

vernier fore-aft _____________________

vernier lateral ______________________

Class
basophil

Appearance
cytoplasmic grains dark blue, less numerous, lobes less distinct, larger

Function
Similar to mast cells, contain histamine and heparin

% total leukocytes
0.5 – 1%

vernier fore-aft _____________________

vernier lateral ______________________

Other images of leukocytes

basophil_P4013817

basophil:

eosinophils:

monocyte_P4013823

monocyte:

neutrophils:

Slide 2.  Artery and vein (H1750) p. 113 & 115, 100x: endothelium
Contrasting histology of arteries and veins (See Martini’s 5th: p 693):

TISSUE LAYERS
tunica intima
ARTERY
endothelium (a simple squamous epithelium), attached to internal elastic lamina
VEIN
endothelium


TISSUE LAYERS
tunica media
ARTERY
smooth muscle, a thick band, attached to the external elastic lamina
VEIN
smooth muscle, a thin band


TISSUE LAYERS
tunica externa
ARTERY
adventitia with vasovasorum
VEIN
adventitia with vasovasorum


Here is a labeled view of an artery and a vein which contrasts their composition.

Artery_Vein_nerve_40x_P4043320crop

Arteries are thicker walled, have a smaller diameter, and hold themselves open. Veins are larger diameteres, thinner walled, and “floppier.”
You can also see adipose tissue and, in the upper right, two nerves.

Artery_100x_P4043316crop

This is a 100x view of an artery. Note again its open lumen and thick wall.

Artery_400x_P4043315crop

At 400x, the artery displays the internal elastic lamina, the thick tunica media, composed of smooth muscle, and the outermost adventitia or tunica externa. Red blood cells can be seen in the lumen.

vein_400x_P4043314crop

A 400x view of a vein shows little evidence of elasticity of the tunica intima, and a sparce amount of tunica media

Label the following in your illustrations of an artery and vein:
internal elastic lamina
tunica media
tunica adventitia
adipose tissue

VERNIER SCALE ADDRESS OF LEUKOCYTES

Fill in this table, and place in the slide box:
Vernier scale leukocyte addresses form:
Record slide set number, the addresses, your name and the date. Place in the slide box

Slide Set:______ Fore/Aft Lateral
neutrophil
basophil
eosinophil
lymphocyte
monocyte
Student: ______________________Date:________