Venous Circulatory system Flashcards
Heart
Four chambered
Right half circulates blood from body to lungs
Left half circulates blood from lungs around body
How is blood forced through the body
By a pressure system
Right side circulation
Little peripheral resistance, so lower pressures needed
Right ventricles are thinner as a result
Left side circulation
Pumps same volume as right but against greater resistance
Left ventricular walls are more muscular
Resistance vessels
Consist of the muscular arterioles and precapillary sphincters
Provide the principle resistance to blood flow and regulates the pressure in the arterial tree
Arteries and arterioles
High pressure system
Low volume
Venous system
Carries most of the blood in the body
Low pressure and high volume system
Do you see lymphatic vessels on ultrasound
No but you do see lymph nodes
Single called capillary walls exchange
Oxygen CO2 Nutrients Water Inorganic ions Vitamins Hormones Metabolic products Immune substance between blood and tissue fluids
Lymph capillaries coexist with
Blood blood capillaries in capillary beds
Can exchange anything from liquids to cells
What is the percentage of fluid that leaks from blood capillaries into tissues that does not return
10-20%
What would happen if the fluid was left in the tissues
It would gradually flood causing edema
Lymphatics
Located alongside veins
Absorb excess fluid
Venules
Tributaries of veins
Collect blood from capillary beds
Smaller unit of veins
Capacitance vessels
Provide a low pressure blood reservoir through which blood returns to the heart
Vena combatants
Paired veins often accompany arteries
Veins
Hold 2/3 blood volume
Low pressure blood reservoir, how blood returns to the heart
Blood is collected in cap bed in venules
Valves
Prevent reverse flow
Pockets in the walls
Found where a tributary joins a larger vein and at intervals along main veins
What cause valve leaflets to close and stops the flow
Reflux blood pouring into the pockets and fills them
What helps valves
Small veins
Average blood volume of an adult
5L
most common blood cell, what does it transport
Erythrocyte
Transports oxygen and carbon dioxide
Second most common cell type
Leukocytes
Platelets
Third type of blood cell
Aggregate in clumps
Involved with wound repair and blood clotting
Leukocytes
Are the defence mechanisms
All unoxygenated venous blood that returns enters the right atrium via
Superior vena cava
Inferior vena cava
Venous flow is
From venules to the heart
Oxygen blood is returned _of the _via the _
Left atrium
Heart
pulmonary veins
Blood is collected in
Venules
Confluences
The merging points of different veins coming together
Vasa vasorum
Found in the tunica adventitia
A network of tiny vessels that supply the walls of large veins and arteries with nutrients and oxygen
Bicuspid
2 layers
Valves
Unique to venous system Usually bicuspid Arise from the intimal layer Allow for one way flow Present in upper and lower extremity Number of valves increase as distance from heart increases
Svc
Formed by the junction of the right and left brachiocephalic veins
Brachiocephalic vein
Formed by the junction of the internal jugular and subclavian veins
Tributaries of the subclavian veins
Vertebral and external jugular veins
External jugular veins
Drain the superficial areas of the scalp and face
Vertebral veins
Drain the cervical vertebrae, spinal cord, small neck muscles
Internal jugular veins
Drain most of the blood from the brain and deep areas of the face and neck
Largest veins of the head and neck
Duran sinuses
Argue interconnected chambers that lie between the dura mater layers
Not true veins but collect the blood from the brain to drain into the internal jugular veins
Major sinuses: superior and inferior Sagittal sinuses, straight, transverse, canvernous, sigmoid and petrosal sinuses
Inferior vena cava
Largest we in in the body
Formed by the union of the common iliac vein @ L5
Passes posterior surface of the liver, passes through the diaphragm, enters the right atrium of heart
Renal veins
Drain from the hilum of each kidney
Lie anterior to the artery and empty into lateral walls of IVC
Left renal vein travels posterior to the SMA and anterior to aorta
Right renal vein is shorter and travels more inferiorly than the left
Hepatic veins
Short veins that collect blood from the liver
Empty in the IVC just below the diaphragm
Right and left hepatic drain the right and the left lobes of the liver
Middle hepatic drain the medial segment of the left lobe and the anterior segment of the right lobe
Portal system
Delivers 3-quarters of the livers blood flow
Separate system from the venous circulation
Consists of: MPV, SMV, SV, IMV
Main portal vein
Forms behind the neck or head of the pancreas by the confluence of the smv and the sv
Length averages between 5.5-8.0 cm with a 1cm diameter
Runs behind the first portion of duodenum to the porta hepatis, divides into right and left portal branches
Receives the left and right gastric veins and the left branch of the paraumbilical vein
Paraumbilical vein
Rement of the umbilical chord, located in the main portal vein
