Download The Cardiovascular System

The Cardiovascular System
EFE Veterinary Science
Anatomy and Physiology
The Heart: Overview
Schematic drawing of the systemic and
pulmonary circulation. 1, Left ventricle;
2, aorta; 3, capillary bed of head, neck,
and forelimb; 4, abdominal aorta; 5,
liver; 6, capillary bed of intestines; 7,
portal vein; 8, capillary bed of kidneys;
9, capillary bed of caudal part of the
body; 10, caudal vena cava; 11, cranial
vena cava; 12, right ventricle; 13,
pulmonary trunk; 14, capillary bed of
lungs; 15, pulmonary vein; 16, hepatic
veins.
The Heart: Structure
Section of the heart exposing the four chambers. 1, Cranial vena cava; 2, terminal sulcus; 3, right
atrium; 4, interatrial septum; 5, left atrium; 6, left atrioventricular valve; 7, right atrioventricular
valve; 8, right ventricle; 9, interventricular septum; 10, left ventricle; 11, sinuatrial node; 12,
atrioventricular node; 13, 14, right and left limbs of atrioventricular bundle.
The Heart
Left (A) views of the heart. A, 1, Left auricle; 2, pulmonary trunk; 3, right ventricle;
4, left ventricle; 5, left azygous vein.
The Heart: Structure
Right (B) views of the heart. B, 1, Right atrium; 2, caudal vena cava; 3, aorta; 4, right
azygous vein (opening into the cranial vena cava).
Major Vessels
• Aorta (exits left ventricle)
• Pulmonary Arteries (exit right
ventricle)
• Pulmonary Veins (enter left atrium)
• Vena Cava (enters right atrium)
• Know location and oxygenated v
deoxygenated blood
Blood Flow
• Capillaries”drops off” O2
• Deoxygenated blood returns via the veins
to the Vena Cava
• Vena CavaRight atrium
• Right atriumright AV valveright
ventricle
• Right VentriclePulmonic
valvePulmonary Arteries
Blood Flow, 2
• Pulmonary Arterieslungspulmonary
capillaries in alveoli, pick up O2, release
CO2
• Pulmonary veinsleft atrium
• Left atrium through left AV valveLeft
ventricle
• Left ventricle through Aortic
valveAorta
Blood Flow 3
• Aortaarteries
• Arteriescapillaries, drop off O2, pick
up Co2, repeat cycle.
• Oxygen and pressure higher in arteries
• Pulmonary arteries are the only arteries in
the body that carry deoxygenated blood!
Electrical Activity
• Electrical Activity initiates the contraction of
cardiac muscle.
• Electrical activity is what is measured by an
ECG (aka EKG)
• A Pacemaker produces a small electrical pulse
to cause regular contraction of the heart
Electrical Activity
Schematic drawing of the
conducting system of the heart.
The broken lines suggest the
passage of the excitation wave
through the atrial wall. 1,
Sinuatrial node; 2, atrioventricular
node; 3, atrioventricular bundle; 4,
left limb; 5, right limb; 6, branch of
right limb traversing the
septomarginal band.
Sinoatrial Node (equine)
A, Sinuatrial node of the equine heart. 1, Nodal myofibers; 2, bundle of nerve fibers
(I-HE) (279×).
The Electrocardiogram (ECG/EKG)
ECG
Heart Sounds
• 2-part sounds: Lub—Dub
• First sound (lub) is physical closing of
the right and left AV valves
• Second sound (dub) is physical closing of
the aortic and pulmonic valves
• A murmur is caused by flow through a
narrow opening (leaky valve, congenital
abnormality)
Heart Sounds
Arteries
Carry blood away from heart
Under high pressure
Can feel pulsation
The components of the arterial wall. 1, 2,
Tunica interna (1, endothelium; 2, inner
elastic membrane); 3, tunica media; 4, tunica
adventitia; 5, vasa vasorum.
Arteries
The branching of the arteries. Note that (1) the sum of the cross-sectional areas of
the branches always exceeds that of the parent trunk; (2) large branches leave the
trunk at more acute angles than smaller branches; and (3) the smallest branches
leave erratically.
Capillaries
Single cell thick walls for transfer of O2 and CO2 between blood and tissue
Schematic drawing of a capillary plexus. 1, Arteriole; 2, venule; 3, communicating
(low-resistance) channel; 4, closed capillaries; 5, open capillaries; 6, precapillary
sphincters.
Veins
Schematic representation of the venous
system (dog). 1, Caudal vena cava; 2, cranial
vena cava; 3, azygous v.; 4, vertebral v.; 5,
internal jugular v.; 6, external jugular v.; 7,
linguofacial v.; 8, facial v.; 8′, angularis oculi v.;
9, maxillary v.; 10, superficial temporal v.; 11,
dorsal sagittal sinus; 12, subclavian v.; 12′,
axillobrachial v.; 12″, omobrachial v.; 13,
cephalic v.; 13′, accessory cephalic v.; 14,
brachial v.; 15, radial v.; 16, ulnar v.; 17,
internal thoracic v.; 18, vertebral venous
plexus; 19, intervertebral v.; 20, intercostal vv.;
21, hepatic vv.; 22, renal v.; 22′, testicular or
ovarian v.; 23, deep circumflex iliac v.; 24,
common iliac v.; 25, right internal iliac v.; 26,
median sacral v.; 27, prostatic or vaginal v.; 28,
lateral caudal v.; 29, caudal gluteal v.; 30,
internal pudendal v; 31, right external iliac v.;
32, deep femoral v.; 33, pudendoepigastric
trunk; 34, femoral v.; 35, medial saphenous v.;
Veins
• Function: Return deoxygenated blood
to the heart for gas exchange in the
lungs
• Structure: Thinner-walled than
arteries due to lower pressure than
arteries
Veins
A branching vein opened to expose valves. The arrow indicates the direction of
blood flow.
Baroreceptors and Chemoreceptors
Function: To sense blood pressure and
chemical composition of blood for
feedback to the circulatory and
endocrine systems.
Baroreceptors and chemoreceptors at
the origin of the internal carotid
artery. 1, Common carotid artery; 2,
external carotid artery; 3, internal
carotid artery; 4, carotid sinus branch
of the glossopharyngeal nerve; 5,
carotid sinus (baroreceptor); 6, carotid
body (chemoreceptor).
Fetal and Postnatal Circulation
Semischematic drawing of fetal circulation (calf). 1, Thymus; 2, pulmonary trunk; 3, aortic
arch; 4, ductus arteriosus; 5, pulmonary artery; 6, foramen ovale; 7, wall of left ventricle;
8, caudal vena cava; 9, ductus venosus; 10, junction of umbilical and portal branches
within the liver; 11, umbilical vein; 12, stump of portal vein; 13, left umbilical artery; 14,
gallbladder; 15, descending colon.
Fetal and Postnatal Circulation
Diagrams of the fetal (A) and postnatal (B) circulatory systems. 1, Cranial vena cava; 2,
caudal vena cava; 3, right atrium; 4, arrow entering oval foramen; 5, right ventricle; 6,
pulmonary trunk; 7, pulmonary artery; 7′, ductus arteriosus (in B, vestige); 8, left
atrium; 9, left ventricle; 10, aortic arch; 10′, descending aorta; 11, umbilical artery; 12,
umbilical vein; 12′, ductus venosus; 13, liver; 14, portal vein.
Umbilical Cord and Placental
Circulation
• Umbilical veinfetal livercaudal vena
cavaright atrium OR foramen
ovaleleft atrium; RA mixes with
other venous returnpulm
trunkductus
arteriosusaortaumbilical
arteryplacenta; LALVaortic
archaortaumbilical arteryplacenta
Umbilical Cord and Placental
Circulation
• Postnatal changes: Closure of
umbilical artery and vein; closure of
foramen ovale; closure of ductus
arteriosus; closure of ductus venosus
and adult-pattern liver circulation
Lymphatics
Generalized schema of the lymph nodes
and lymphatic vessels (dorsal view). The
top of the diagram represents the neck
region. 1, External and internal jugular
veins; 2, lymph from the head; 3, lymph
from the shoulder and forelimb; 4,
tracheal duct; 5, thoracic duct; 6, lymph
from the thoracic organs; 7, cisterna chyli;
8, lymph from the abdominal organs; 9,
lymph from the lumbar region and
kidneys; 10, lymph nodes of the pelvis;
11, lymph from the hindlimb.
Lymphatics
Structure of a lymph node (A) in which the
germinal centers (lymph nodules) occupy the
cortical region. In the pig (B) the germinal
centers lie centrally. The arrows indicate the
direction of lymph flow. 1, Afferent
lymphatics; 2, subcapsular sinus; 3, efferent
lymphatics.
Lymph Nodes
Lymph node (dog) (28×). 1, Cortex with
lymph nodules; 2, medulla; 3, afferent
lymph vessels.
A, Lymph node (pig) (28×). 1, Loose
lymphoreticular tissue; 2, lymph
nodules in centrally located “cortex”;
3, efferent lymph vessels.
Lymph Nodes
Palpable lymph nodes of the dog. 1, Parotid; 2, mandibular; 3, lateral
retropharyngeal (inconstant); 4, superficial cervical; 5, axillary; 6, accessory axillary
(inconstant); 7, superficial inguinal; 8, popliteal; 9, femoral (inconstant).
Lymph Nodes
Palpable lymph nodes of the cat. 1, Mandibular; 2, lateral retropharyngeal; 3,
dorsal superficial cervical; 4, axillary; 5, accessory axillary; 6, superficial inguinal; 7,
caudal epigastric; 8, popliteal.
Lymph Nodes
Lymph nodes associated with
trachea and lungs of the dog.
1, Cranial mediastinal nodes;
2, tracheobronchial nodes; 3,
pulmonary nodes.
Lymphatic Vessels
• Very thin-walled
• Very low-pressure system
• Passive circulation: Lymph moved by the
motion of surrounding tissue
• Pregnant women with swollen ankles
• Horses stocking up
Spleen
Visceral surface of the spleens of horse (A), cattle (B), and dog (C) to show the
distribution of the splenic arteries. Branches to other structures are shown in blue.
Spleen
• Structure: Capsule, cortex and medulla
– Lymphatic nodules
– Blood Storage and Filtration
– Can contract to release blood during times of high
demand
• Prone to hematoma and hemangioma or
hemangiosarcoma leading to splenectomy
Thymus
Thymus of calf (HE) (70×). 1, Thymic lobules; 2, capsule.
Thymus
• Thymic cortex is origin of T
lymphocytes
• Medulla has unknown function
• Regresses in adults