Cardiovascular system anatomy Flashcards
The circulatory system functions as
The circulatory system functions as the transport system
Delivers oxygen, nutrients, hormones and regulatory chemicals to all cells
Transports carbon dioxide and other products of metabolism from the cells to the lungs, liver and kidneys
Distributes heat from inside the body to the extremities and vice versa
Circulatory system consists of
Heart, vessels, blood
Arteries
Carry blood away from heart
Vein
Carry blood towards the heart
Lymphatic vessels
Vessels that carry tissue fluid (or lymph) to large veins are called lymphatic vessels or lymphatics
Location of the heart in a canine
Extends from 3rd to 6th intercostal space
Long axis of heart forms a 45o angle with the sternum but varies between breeds
Deep chested breeds have a larger angle; barrel chested have a lower angle
Location of the heart of a cat
Extends from 3rd/4th to 6th/7th intercostal space
Forms a more acute angle so has increased sternal contact compared to dogs
Location of the heart of a equine or ruminnets
The heart is placed asymmetrically mostly on the left side
Located from the 2nd to the 5th intercostal space
Apex is at the level of the point of the elbow
Bovine has os cordis (small bone) within the heart to support the valves
Layers of the heart
Pericardium, myocardium, endocardium
The fibrous pericardium is the
is the thin fibrous-serous covering of the heart
The fibrous pericardium is outermost, extends to the diaphragm and covers major vessels at the heart base
Pericardium is the
Thin fibrous serous covering of the heart
Serous pericardium of the heart
lines the fibrous pericardium
This is the parietal layer
The visceral layer covers the heart itself
The fluid filled space between these layers is called the pericardial space or cavity
Myocardium is the
Is the muscle layer of the heart and is sandwiched between the visceral pericardium and the endocardium
Endocardium is the
thin membrane covering of the internal surface of the heart
Atrium is
which receives blood from large veins
A ventricle pumps blood from…
the heart via large arteries
R AV
Right tricuspid valve
L AV
Bicuspid or mitral valve
Atrioventricular valve connects
Connecting each atrium and ventricle is a large valve called the atrioventricular valve or AV valve
Leaflets do what
Heart valves have leaflets (cusps) which prevent the backflow of blood
Right atrium is and does
Thin walled
Receives systemic (means all part of body except lungs) veins
Blind ended portion known as the right auricle
Right ventricle is and does
More muscular than the atrium but a thinner wall than the left ventricle.
Does not reach apex of heart
Receives outflow from right atrium by way of the right AV (tricuspid) valve
Has papillary muscles (protrusions of cardiac muscle) which anchor the AV valve through chordae tendinea
Pulmonary trunk and semilunar valve is and does
The pulmonary trunk drains the right ventricle
Connects right ventricle to the pulmonary arteries
The pulmonary semilunar (three crescent moon shaped cusps) valve sits at the base (beginning) of the pulmonary trunk
Left atrium is and does
Thin walled chamber
Receives pulmonary veins
Left auricle – similar to right atrium
Left ventricle is and does
Thick walled and forms the apex of the heart
Receives outflow from left atrium by way of left AV (mitral) valve
Left AV valve is supported by chordae tendinea and papillary muscle
Aortic semilunar valve is where
Separates left ventricle from aorta
Aorta disturbs what from where
Distributes blood from Left ventricle to the body
Interventricular septum is where
Partition b/w ventricles
Interatrial septum is where
Partition b/w atria
Valves are and do
All the heart valves occur at approximately the same level in the heart.
Anchored in the connective tissue that separates the atria from the ventricles.
Function as one way valves
Av valves do what
- One border of the cusp (valve leaflet) is attached to the inner wall of the ventricle at the junction of atrium and ventricle
- The free borders are loosely attached to the wall of the ventricle by chordae tendinae which are fibrous cords resembling the strings of a parachute
- The chordae tendinae prevent the valves from flipping into the atria when the ventricles contract
- Instead, the AV valve closes as the blood in the ventricle pushes the valve leaflets together
- Blood must leave by the aorta or pulmonary trunk
The two semilunar valves are and do
Aortic and pulmonary
Prevent blood from returning into the ventricles when the ventricles relax
Arteries come from and turn into
Arteries have thicker, more muscular, walls than veins
Arteries start as large vessels which carry blood away from the heart and divide into smaller and smaller branches
Smaller arteries are called arterioles , which feed the capillaries
Capillaries are
thin walled tubes which are only wide enough for one red blood cell
The walls of capillaries are
selectively permeable for small molecules
Water, oxygen and nutrients leave the blood to enter the tissue
Waste products from the tissues to enter the blood
Excess fluid is removed from the
Lymph vessels
Capillaries unit into
Once capillaries have passed through the tissue they unite to form venules which in turn unite to form larger and larger veins
The largest veins empty into
some are called vena cava, then empty back into the heart
Compared to arteries veins are
Larger
Have thinner walls
Are more superficial
Contain valves , usually where 2 or more veins unite to form a larger vein
These valves prevent blood from being forced back into capillary beds
Flow has to be towards the heart
First step after blood is pumped into tissue capillaries
Fluid is forced out at the arterial end by the hydrostatic pressure generated by the heart
This is filtration: only water and small molecules (ions and nutrients) can get through the gaps between cells
Second step after blood is pumped into tissue capillaries
Fluid is reabsorbed back into the capillary at the venule end
Hydrostatic pressure is low
Plasma proteins are more concentrated
Their osmotic pressure draws water back in
Oncotic pressure is the name for this part of osmotic pressure generated by molecules (mainly albumin) that are too large to escape through capillary pores
Edema can result form excssively
Leaky blood vessels
High hydrostatic pressure (heart failure)
Low oncotic pressure (low albumin) e.g. liver failure or GI disease
Two circulatory system and what they supply
a pulmonary circulation that supplies the lungs and a systemic circulation that supplies everything else
Venous blood oxygen content
Low in oxygen content
Atrial blood oxygen content
High in oxygen content
Flow of blood from tissue to pulmonary arteries
Unoxygenated blood from tissues → veins → cranial and caudal vena cava → right atrium → right atrio-ventricular valve (AV, tricuspid) → right ventricle → pulmonary semilunar valve → pulmonary trunk → left and right pulmonary arteries—> lungs
Blood flow of Oxygenated blood to body to tissue of body
Oxygenated blood to body → Left and right pulmonary veins → left atrium → left atrio-ventricular valve (AV, bicuspid, mitral) → left ventricle → aortic semilunar valve → aorta → arteries → tissues of body
Is pulmonary vein oxygenated
Yes
IS systemic vein oxygentaed
No
Pulmonary circulation circulates through the
The part of the vascular system that circulates all the blood through the lungs .
Pulmonary circulation consists of
The part of the vascular system that circulates all the blood through the lungs .
Consists of a pulmonary trunk supplying pulmonary arteries which in turn supply capillaries before being collected in pulmonary veins and returned to the left heart.
Vast capillary network running very close to the alveoli of the lungs.
Pulmonary circulation goes through
Oxygen from air inspired into the alveoli is exchanged for carbon dioxide in the blood.
As gas exchange occurs, the colour of the blood changes from the dark red colour of unoxygenated blood to the bright red colour of oxygenated blood
The place where blood is unoxygenated in the arteries
The pulmonary circulation is the only place where unoxygenated blood is found in the arteries and oxygenated blood is found in the veins
Somatic circulation carries
Systemic circulation
Carries oxygenated blood to all areas of body except the lungs and then returns unoxygenated blood to the heart.
Aorta carries
Blood from left v of the heart to tissues
3 segments of aorta
Ascending aorta
Aortic arch
Descending aorta
Ascending aorta is located in
Connects L. ventricle to aortic arch
Supplies the coronary arteries
Descending aorta further subdivided
Thoracic and abdominal portions
Two branches from the aortic trunk
Brachiocephalic trunk and left subclavian artery
Brachiocephalic trunk is and branches into
supplies the head and the right thoracic limb. Branches into:
Common carotid arteries: supply the head
Right subclavian artery: supplies the right thoracic limb
Left subclavian artery is into
supplies the left thoracic limb
the subclavian arteries continue down the thoracic limb as the axillary arteries which become the brachial arteries, then the median arteries.
The descending aorta branches into
Celiac artery
Cranial mesenteric artery
Renal arteries
Testicular or ovarian arteries
Caudal mesenteric artery
Iliac arteries (external and internal)
Median sacral artery
Celiac artery is and divides into
an unpaired artery starting just caudal to the diaphragm
Divides into 3 branches
Hepatic artery: goes to the liver
Left gastric artery: goes to the stomach
Splenic artery: goes to the spleen
Cranial mesenteric artery is and supplies
unpaired, originates caudal to the celiac artery
Supplies branches to most of the intestines
Renal arteries are
Paired arteries which supply the kidneys
Testicular or ovarian arteries are
paired arteries supply the testes or ovaries.
Originate caudal to the renal arteries
Caudal mesenteric artery supply
unpaired artery, supplies the descending colon
External iliac arteries are paired with and go to
paired arteries which continue down the pelvic limb as femoral arteries, become the popliteal arteries, then the cranial tibial arteries
Iliac arteries supply
supply pelvis and pelvic limbs
Internal iliac arteries are paired with
paired arteries that branch off just caudal to the external iliac and supply the gluteals
Medial sacral artery is the
unpaired. A continuation of the aorta that supplies the tail. Sometimes called the caudal artery
Hepatic portal circulation
A portal circulation carries blood from the capillaries of one organ to those of another.
There are several portal systems in the body.
Blood drains from capillaries of the stomach, spleen, intestines and pancreas
Enters mesenteric, gastroduodenal and splenic veins
Collected into the (hepatic) portal vein
Transported to the liver where blood enters sinusoids (like large capillaries).
Portal circulation
In the liver nutrients can be modified and/or stored for future use
Also gives the liver a chance to detoxify any harmful substances that may have been absorbed from the digestive tract
The blood passes from sinusoids into the central veins of each liver lobule and eventually form hepatic veins (not part of the portal system) which empty blood into the caudal vena cava.
Coronary circulation
Left and right coronary arteries come off the root of the aorta
Supplies blood to the myocardium
In people, it can become blocked by fatty deposits resulting in damage to the heart muscle, called a coronary. Treated by balloon angioplasty or bypass surgery
Vena cava is
the cranial and caudal vena cava are the large veins returning from the cranial and caudal parts of the body. They enter the heart at the right atrium
Cranial vena cava is the
returns blood from head and thoracic limbs
Formed by the convergence of the right and left brachiocephalic veins.
These are are formed by the external and internal jugular veins from the head and the subclavian veins from the thoracic limbs
Caudal vena cava is
returns blood to the heart from pelvis, pelvic limbs, abdomen, and thoracic cavity
Common iliac veins are
drain blood from the pelvic limbs into the caudal vena cava
Testicular or ovarian veins are
on right side located just caudal to the renal veins; on the left side it joins the renal vein prior to draining into caudal vena cava
Drain testicles or ovaries
Renal veins drain
Kidneys
Portal veins transports
transports blood from spleen and digestive tract to liver
Part of the portal circulation (discussed later)
Hepatic vein drains
Liver
Empty into the caudal vena cava
Azygous vein drains
Part of the thoracic cavity and abdomen
Fetal circulaiotn
Fetal blood circulates through the placenta (which is physically distinct from the fetus itself).
Carbon dioxide and waste products in the fetal blood are exchanged for oxygen and nutrients from the blood of the mother.
In the fetus, the lungs are collapsed and non functional, they resist blood flow through the lungs.
Blood is diverted from the right side of the heart to the left side
Blood from the placenta enters the fetus through the umbilical veins (oxygenated)
What happens to the fetal circulation at birth
Air expands the lungs making blood flow easier
The foramen ovale and ductus arteriosus close
Initially by muscle contraction
Later by fibrosis
The attachment to the placenta is lost and umbilical arteries and veins atrophy
The ductus venosus closes
Blood is diverted from the right side to the left through the in fetal
A hole between the atria called ovale
A direct connection from the pulmonary trunk to the aorta called the ductus arteriosus.
Blood from the umbilical cord goes through
Pass through the abdomen
Travels through the ductus venosus
Bypasses the liver
Drains directly into the vena cava
