Cardiovascular System Flashcards
What is the cardiovascular system also know as?
The circulatory system
-bc blood continuously flows around animal’s body propelled by the heart
Pulmonary Circulation
refers to the lung
-controlled by the right, receives deoxygenated blood
Systemic Circulation
refers to the body
-controlled by the left, receives oxygenated blood
What do arteries do?
carry blood away from the heart
What do veins do?
carry blood toward the heart
What do capillaries do?
form the transition between arteries and veins
Where is the heart located?
in the middle of thoracic cavity/ the MEDIASTINUM
What is the mediastinum?
in the space b/w the 2 lungs
-contains blood vessels, the esophagus, trachea, thymus in young animals, LN and nerves
Where does the apex sit?
shifted to the left and sits more ventrally
What is the pericardium?
fibrous sac containing the heart; has 2 parts:
1. pericardial sac
2. serous pericardium
Pericardial sac
more fibrous, a little loose so that the heart has space to pump
Serous pericardium
visceral layer- on heart
parietal layer- on sac
What is the pericardial space filled with?
pericardial fluid b/w the 2 serous pericardial layers
What are the 3 layers in the heart wall?
- epicardium
- myocardium
- endocardium
Epicardium
-most superficial
-serous pericardium
Myocardium
muscle
Endocardium
-lies on the internal surface of myocardium
-continuous with endothelium of the blood vessels
-cover papillary muscles
Atria (plural) /Atrium (singular)
sits on top of heart to form the base
-receives blood into heart
-separated by interatrial septum
-when filled with blood, walls contract and send blood to ventricles
Ventricles
sit below atria to form apex
-separated by interventricular septum
-pump blood out of the heart
What does the right ventricle do?
pumps blood to pulmonary circulation through the pulmonary artery
What does the left ventricle do?
pumps blood to the rest of the body through the aorta
What are auricles?
R/L
blind pouches that come off the atria
What is the inter ventricular groove?
-formed by the interventricular septum but on the the visible surface of the heart
-CONTAINS CORONARY BLOOD VESSELS AND FAT
Cardiac Valves
4 one way valves control blood flow through the heart
Chordae tendonae
prevent valves from opening backwards
What are Atrioventricular valves (AV valves)
between the atrium and their respective ventricles (2)
1. Tricuspid valve
2. Mitral valve
Tricuspid valve
Right AV valve
Mitral valve
aka Bicuspid valve
Left AV valve
What are the semilunar valves?
- Pulmonary valve
- Aortic valve
Pulmonary valve
b/w the right ventricle and pulmonary artery
Aortic valve
b/w the left ventricle and the aorta
Skeleton of the heart
-located b/w the atria and ventricles
-4 dense fibrous c.t. tissue rings
What are the 4 primary functions of the skeleton of the heart?
- separates atria and ventricles
- anchors heart valves
- point of attachment for myocardium
- electrical insulation b/w atria and ventricles
Coronary arteries
branch off aorta
Coronary veins
coronary sinus drains into right atrium
Nerve supply to heart
not essential but serves a purpose
(cardiac muscle creates its own contractions and relaxations)
What happens during the cardiac cycle?
-one heartbeat is produced
-one cycle of the atrial and ventricular contraction followed by relaxation
-each chamber goes through systole and diastole but not at the same time
Systole
myocardium contracting, “working”
Diastole
myocardium relaxing and repolarizing
Normal heart sounds
-produced by heart valves snapping shut
-one cardiac cycle produces two distinct heart sounds
lub
after atrial systole= S1
tricuspid and mitral valves snap shut
dub
after ventricular systole= S2
pulmonary and aortic valves snap shut
PAM
-you can hear pulmonic, aortic, and mitral valves best on the left
-tricuspid on the right
Abnormal heart sounds
extra sounds heard when 2 AV valves or 2 semilunar valves are not closing simultaneously
-valvular insufficiency (don’t close all the way) and valvular stenosis (won’t open all the way)
What is Cardiac Output?
volume of blood that is ejected out of the left ventricle over a unit of time, usually a minute
CO = SV x HR
What is Stroke Volume?
-represents the strength of the heartbeat
-determined by 2 factors: preload and afterload
Preload
volume of blood received from the atrium
Afterload
physical resistance by artery the ventricle is ejecting blood into
Characteristics of Arteries
-usually come in pairs
-2 types: elastic and muscular
Largest elastic artery
aorta
Smallest branch of arterial tree
arterioles
Characteristics of Capillaries
-microscopic blood vessels from branching arterioles
-occur in groups called capillary beds/networks
-walls are one endothelial cell thick
Characteristic of veins
-capillaries join together to form venules
-one way valves and muscular movements (working against gravity)
All systemic veins drain into
vena cava
How does a fetus receive oxygen?
from the blood of its mother (placenta) through the umbilical cord
What is pulse?
rate of alternating stretching and recoiling of elastic fibers in an artery as blood passes through with each heartbeat
-auscultation is not a true pulse
What happens after first breath?
foramen ovale and ductus arteriosus close so that blood no longer bypasses the lungs
What is blood pressure?
amount of pressure that flowing blood exerts on arterial walls; dependent on:
-heart rate
-stroke volume
-diameter and elasticity of the artery
-total blood volume
Systolic blood pressure
highest number
Diastolic blood pressure
lowest number
Mean arterial pressure
average pressure during one cardiac cycle
Oscillometric method
cuff placed over artery
-not good for animals with high HR or arrythmias
Doppler ultrasound
-transducer attached to sphygmomanometer
-accurately measures systolic blood pressure only
-preferred method for cats and small dogs
