The Vascular System Flashcards
What is the main job of the vascular system
To exchange materials between the blood and tissues, takes place in the capillaries. The arteries and veins are just as important by transporting blood between the capillaries and the heart
What does the vascular system consist of
Arteries, capillaries, and veins through which the heart pumps blood through the body
What is blood pressure
The force the blood exerts against the walls of the vessels
What do arteries do
Carry blood from the heart to the capillaries
What are small arteries called
Arterioles
What are the three layers or tunics of tissues in an artery
Tunica intima
Tunica media
Tunica externa
What is the innermost layer of the artery
Tunica intima
Which layer of the artery is the only part that is in contact with blood
Tunica intima
What is the Tunica intima made of
Simple Squamus epithelium also called endothelium
What is the function of the endothelium in the Tunica intima
It has extreme smoothness and normal chemical composition which prevent abnormal blood clotting by preventing the adhesions of platelets
What chemicals does the endothelium produce which affect blood pressure
Nitric oxide (NO)which is a vasodilator, it stimulates relaxation of smooth muscle of the middle layer of the vessel
The peptide endothelin stimulates contraction of the smooth muscle and is therefore a vasoconstrictor
What is the middle layer of the artery
Tunica media
What is the Tunica media made of
Smooth muscle and elastic connective tissue
The smooth muscle and elastic connective tissue in the Tunica media are involved in the maintenance of what
Blood pressure, especially diastolic blood pressure when the heart is relaxed
Smooth muscle also has a nerve supply what can happen if impulses are increased or decreased
Increased sympathetic nerve impulses bring about vasoconstriction, and a decrease in impulses contributes to vasodilation
What is the outer layer of the artery
Tunica externa
Which layer of the artery is very strong and why is this important
Tunica externa. it is important because it prevents the rupture or bursting of the large arteries which carry blood under high-pressure
What enables the arteries to construct or dilate
The smooth muscle layer
Such changes in diameter of the arteries when they constrict or dilate is regulated by what three things
Endothelium, Medulla, and autonomic nervous system
What is the function of the veins
The carry blood from the capillaries back to the heart
What difference does the inner layer of a vein have compared to the inner layer of the artery
They both have smooth the endothelium but in intervals the lining of the veins will fold to form valves
What do the valves preevent in the veins
Backflow of blood— (and they are most numerous in veins of the legs where blood must often return to the heart against the force of gravity)
The middle layer of veins is thin. It is thin why
Because veins do not regulate blood pressure and blood flow into capillaries as arteries do
Veins can constrict extensively. Why is this important
It is useful in case of severe hemorrhage
The outer layer of veins is also thin compared to the arteries. Why is this necessary
Because blood pressure in veins is very low
Comparing veins and arteries which one has a greater capacity
Veins, their total volume is greater
What is an anastomosis
It is a connection, or joining of vessels, that is, artery to artery or vein to vein
What is the purpose of the connection with anastomosis
To provide alternate pathways for the flow of blood if one vessel becomes obstructed
And arterial anastomosis will help ensure what
That blood will get to the capillaries of an organ to deliver the oxygen and nutrients and to remove the waste products
What will a Venous anastomosis ensure
That blood will be able to return to the heart in order to be pumped again
Where are venous anastomoses most numerous
Among the veins of the legs where the possibility of obstruction increases as a person gets older
What do capillaries do
Carry blood from arterioles to venules
Which tissues do not have capillaries
Epidermis, cartilage, and the lens and cornea of the eye
What does the quantity or volume of capillary networks in an organ reflect
The metabolic activity of the Organ
Blood flow into capillary network’s is regulated by smooth muscle cells which are called
Precapillary sphincters
Why are precapillary sphincter’s usually slightly constricted
Because there is not enough blood in the body to fill all of the capillaries at once
What is an example of when the precapillary sphincter’s would dilate to increase bloodflow
In an active tissue that requires more oxygen, such as exercising muscle.
What are sinusoids
A type of capillary which is larger and more permeable than others.
What does the permeability of sinusoids permit
Large substances such as proteins and blood cells to enter or leave the blood
Where might you find sinusoids
Red bone marrow and spleen (where blood cells enter or leave the blood) and organs such as the liver and pituitary gland (which produce and secrete proteins into the blood)
What is hardening of the Arteries
Arteriosclerosis
Which really means that the arteries lose their elasticity, and their walls become weakened
If a week portion of an arterial wall bulges out forming a sac or bubble this is called
Aneurysm
What is a possible cause of an aneurysm
Arteriosclerosis but some are just congenital
Where are the most common sites for an aneurysm
Cerebral arteries and the aorta, especially the abdominal aorta
What can a rupture of the cerebral aneurysm cause
CVA—cerebrovascular accident
What is an inflammation of a vein
Phlebitis
Where is phlebitis most common
Veins of the legs
If a superficial vein is affected bloodflow is usually maintained why
Because there are so many anastomoses among these veins
What are varicose veins
Swollen and distended veins that occur most often in the superficial veins of the legs
What causes varicose vein
Sitting or standing in one place for long periods of time. Without contraction of the leg muscles blood tends to pool in the leg veins stretching their walls. When they become overly stretched the valves within them no longer close properly. These incompetent valves no longer prevent backflow of blood, leading to further pulling and further stretching of the walls of the veins.
What are varicose vein of the anal canal called
Hemorrhoids
Capillaries are the sites of exchanges of materials between the ____and the_____________
Blood
Tissue fluid surrounding cells
What is it called when gases move from their area of greater concentration to their area of lesser concentration
Diffusion
How does oxygen diffuse
From the blood in systemic capillaries to the tissue fluid
How does carbon dioxide diffuse
From tissue fluid to the blood to be brought to the Lungs and exhaled
When the capillary blood pressure is higher what process occurs
Filtration
What is filtration
Forces plasma and dissolved nutrients out of the capillaries and into tissue fluid
This is how nutrients such as glucose, amino acids, and vitamins are brought to cells
When does blood pressure decreases
When it reaches the Venous end of capillaries
When blood pressure decreases what protein remains in the blood
Albumin
Albumin contributes to the colloid osmotic pressure (COP)of blood what is this
This is an attracting pressure, a pulling rather than a pushing pressure
*At the Venous end of capillaries, the presence of albumin in the blood pulls tissue fluid into the capillaries which brings waste products into the blood that was produced by cells. The tissue fluid returning to the blood also helps maintain normal blood pressure
What are the two major pathways of circulation
Pulmonary and systemic
Where does pulmonary circulation begin
At the right ventricle
Where does systemic circulation begin
The left ventricle
The right ventricle pumps blood into the _____, which divides into the right and left_______, one going to each lung
Pulmonary artery
Pulmonary arteries
What surrounds the alveoli of the Lungs
Pulmonary capillaries
What happens in the area of the alveoli of the Lungs
Exchanges of oxygen and carbon dioxide take place within the capillaries
When capillaries unite what do they form_____
Which merge into_____
And then into the 2 ______
Which return blood to the ______
Venues
Veins
Pulmonary veins from each lung
Left atrium
What veins carry blood with a high oxygen content
Pulmonary veins
Systemic veins have a low oxygen content
Which part of the heart pumps blood into the Aorta
Left ventricle
What do the branches of the aorta do
They take blood into arterioles and capillary networks throughout the body
When capillaries merge what do they form
Venules and veins
Where do the veins from the lower body take blood
To the inferior vena cava
Where do veins from the upper body take blood
To the superior vena cava
What veins return blood to the right atrium
Caval
What are the sections of the aorta
Aspending aorta
Aortic arch
Thoracic aorta
Abdominal aorta
Which section of the aorta is the 1st inch that emerges from the top of the left ventricle
Ascending aorta
Where is the abdominal aorta located
And what arteries does it divided into
Below the level of the diaphragm and continues to the level of the fourth lumbar vertebrae, where it divides into two common iliac arteries
What two branches does the ascending aorta have
Right and left coronary artery’s
What does the left and right coronary artery supplies blood to
The myocardium
What three branches does the aortic arch have
The brachiocephalic artery
The left common carotid artery
The left subclavian artery
Which all supply blood to the head and arms
Which branch from the aortic arch is very short and divides into the common carotid artery and right subclavian artery
Brachiocephalic
Where are the right and left common carotid artery’s
They extend into the neck and divide into an internal carotid artery he and external carotid artery and which supply the head
Where are the right and left subclavian arteries located
In the shoulders behind the clavicles and into the arms
As an artery enters another body area it’s name changes: the subclavian artery becomes the ______which becomes the _______
Axillary artery
Brachial artery
What is a circle of arteries around the pituitary gland in the head
And arterial astomoses,the circle of Willis or cerebral arterial circle
What arteries form the circle of Willis
The right and left internal carotid artery’s and the basilar artery, which is the union of the right and left vertebral arteries which are branches of the subclavian arteries
In the abdominal aorta of the common iliac artery eventually becomes the _____ artery, which becomes the _____artery, which becomes the _______artery
*The same vessel has different names based on location
External iliac
Femoral
Popliteal
What is the hepatic portal circulation
A subdivision of systemic circulation in which blood from the abdominal digestive organs and spleen circulates through the liver before returning to the heart
During hepatic portal circulation blood flows from the capillaries of which areas that lead into two large veins
Stomach, small intestine, colon, pancreas, and spleen
What two large veins does the blood from the capillaries of the stomach flow into
Superior mesenteric vein and splenic vein which unite to form the portal vein
Where does the portal vein take blood
Into the liver, where it branches and empties blood into the sinusoids, the capillaries of the liver
What is the flow of blood from the capillaries of the stomach
They flow into two large veins, the superior mesenteric vein and the splenic vein
Which unite to form the portal vein
The portal vein takes blood into the liver and empties blood into the sinusoids
From The sinusoids blood flows into the Paddock means to the inferior vina cava and back to the right atrium
What does the portal circulation pathway enable the liver to do
To modify the blood from the digestive organs and spleen
Some nutrients may be stored or changed
Bilirubin from the spleen is excreted into bile
And potential poisons are detoxify before the blood returns to the heart and the rest of the body
What is the heartbeat that is felt at an arterial site
Pulse
What is it that you were actually feeling when you feel your pulse
The force of ventricular contraction that is transmitted through the walls of the arteries
Why are pulses not felt in veins
Because veins are too far from the heart
What are the commonly used pulse sites
Radial---thumb side Carotid---the neck Temporal---above the ear Femoral---top of thigh Popliteal---back of knee Dorsalis pedis---top of foot, pedal pulse
Where is the site of exchange of oxygen and nutrients between fetus and mother
Placenta – which contains fetal and maternal blood vessels which are close to each other
How are the substances exchanged between fetus and mother
By diffusion and active transport mechanisms
How was the feed is connected to the placenta
By the umbilical cord
What does the umbilical cord contains
Two arteries and one vein
The umbilical arteries are branches of the fetal internal iliac arteries and how do they carry blood
From the fetus to the Placenta
What thing carries oxygenated blood from the placenta to the fetus
Umbilical vein
With in the body of the fetus, the umbilical vein branches where does the blood go
One branch takes blood to the fetal liver but most of the blood passes through the ductus venosus to the inferior vina cava, to the right atrium
What is the opening in the inter-atrial septum that permits blood flow from the right atrium to the left atrium
Foreman ovale
What is the short vessel that diverts most of the blood in the pulmonary artery to the aorta, to the body
Ductus arteriosus
Both the foreman ovale and the ductus arteriosus permit blood to bypass what
The fetal lungs
Where is blood velocity the slowest and where does it speed up
The capillaries have the slowest blood velocity. When capillaries unite with Venules and veins the area decreases and bloodflow speeds up
river example
The slow rate of blood flow and capillaries is good why
It permits sufficient time for essential exchanges of nutrients wastes and gases
What is blood pressure
The force the blood exerts against the walls of the blood vessels
What does filtration do
Brings nutrients to tissues
What creates blood pressure
The pumping of the ventricles
What is systolic pressure
Represents the blood pressure when the left ventricle is contracting
What is the diastolic pressure
When the left ventricle is relaxed
Where is the systemic blood pressure the highest
In the aorta
Does blood pressure increase or decrease as blood moves away from the heart
Decreases
What is the blood pressure at the arterial end of capillary networks
And what is the blood pressure at the Venous end of capillaries
30 to 35 MM HG
12 to 15 mmHg
As the blood flows through the veins does the pressure increase or decrease
When the blood pressure is in the Caval veins It approaches zero as it enters what area of the heart
Decreases
The right atrium
What area of the heart creates pulmonary blood pressure
The right ventricle
The result of pulmonary arterial pressure being low and even lower and pull Merry capillaries is important to prevent what
Filtration in pulmonary capillaries, which prevents tissue fluid from accumulating in the alveoli of the Lungs
What is venous return
The amount of blood that returns to the heart by way of the veins
Why is venous return important
Venous return is important because the heart can pump only the blood receives. If penis return decreases the cardiac muscle fibers will not be stretched, the force of ventricular systole will decrease in blood pressure will decrease
What three mechanisms help promote venous return
Constriction of veins
The skeletal muscle pump
And the respiratory pump
What does the smooth muscle in veins help to enable
What do the valves prevent
It enables them to constrict and force blood towards the heart
Backflow of blood
What is the skeletal muscle pump especially effective for
The deep veins of the legs. These veins are surrounded by skeletal muscles that contract and relax
Contractions of the leg muscles squeeze the veins to force blood towards the heart
What things does the respiratory pump affect
The veins that passed through the chest cavity
The pressure changes of inhalation and exhalation expand and compress the veins, and blood is return to the heart
What is peripheral resistance
Resistance the vessels offer to the flow of blood.
Why is it important to not exercise after you eat
There is not enough blood to completely supply oxygen to exercising muscles and an active digestive track at the same time.
*Example: after eating a large meal there is vasodilation in the digestive tract to supply more oxygenated blood for the digestive activities. To keep blood pressure within the normal range vasoconstriction must occur somewhere else in the body
What does normal elasticity of the large arteries do for blood pressure
Lower systolic pressure raises diastolic pressure and maintains a normal pulse pressure
What is pulse pressure
Pulse pressure is the difference between systolic and diastolic pressure the usual ratio of systolic to diastolic to post pressure is approximately 3:2:1.
Example: 120/80 blood pressure = 120:80:40, 40 would be the pulse pressure
What determines that the Viscosity of the blood
Red blood cells, plasma proteins especially albumin
What disorder causes too many Red blood cells
Polycythemia vera
What will decrease blood viscosity and blood pressure
What occurs during this type of situation to maintain blood pressure as normal as possible
Decreased number of red blood cells (as in anemia) Decreased albumin (as in liver disease or kidney disease)
Vasoconstriction
Up to what percentage of blood can a person survive a loss of
50% of the bodies total blood
What hormone is secreted from the adrenal Medulla in stress situations
Norepinephrine and epinephrine
What does norepinephrine stimulate
What does epinephrine cause
Vasoconstriction, which raises blood pressure
Epinephrine also causes vasoconstriction and increases heart rate and force of contraction which increased blood pressure
What hormone is secreted by the posterior pituitary gland when the water content of the body decreases
Antidiuretic hormone (ADH)
What does that antidiuretic hormone do
Increases the reabsorption of water by the kidneys to prevent further loss of water in urine and any further decrease in blood pressure
What hormone from the adrenal cortex has a similar effect on blood as the antidiuretic hormone does
Aldosterone.
When blood pressure decreases secretion of aldosterone stimulates the reabsorption of Na+ ions by the kidneys. Waterfall sodium back to the blood which maintains blood volume to prevent further drop blood pressure
What hormone is secreted by the atrium of the heart and functions in opposition to aldosterone
Atrial Natriuretic peptide (ANP)
Increases the excretion of Na+ ions and water by the kidneys, which decreased blood volume and lowers blood pressure
When do precapillary sphincter’s dilate and constrict
They dilate and active tissues and construct and less active ones
Why would arterioles constrict
To reduce blood flow to less active organs. This ensures that active organs will receive enough oxygen to function properly and blood pressure for the body will be maintained in normal limits
What are the two mechanisms of systemic blood pressure
Intrinsic and nervous
What does intrinsic mean
Within
What is starlings law
When venous return increases, cardiac muscle fibers stretch, and the ventricles pump more forcefully
What mechanism are the kidneys involved in
Renin angiotensin mechanism
What do the kidney secrete one blood pressure decreases
Renin
When renin is secreted a series of reactions occur and result in the formation of what
Angiotension II
What does angiotension II cause
Vasoconstriction and stimulates secretion of aldosterone by the adrenal cortex which both increase blood pressure
When a person has a blood level higher in sodium them potassium what does this cause
It will increase the muscle tone of the smooth muscle layer of blood vessels, which raises resting blood pressure
What two mechanisms are directly involved in the regulation of blood pressure
The medulla and the autonomic nervous system
What contains the vasomotor center
The medulla
What does the vasomotor center consist of
A vasoconstrictor area and a vasodilator area
Why do the veins of the legs deteriorate more so than other veins as we age
The walls of the veins in the legs have more pressure because blood is return to the heart against the force of gravity
Vessels are active contributors to homeostasis
Arteries and veins help maintain blood pressure
Capillaries are sites for exchanges of materials between the blood and tissues
Just a summary of everything
What is circulatory shock
Any condition in which cardiac output decreases to the extent that tissues are deprived of oxygen and waste products accumulate
What are causes of circulatory shock
Cardiogenic shock
Hypovolemic shock
Anaphylactic shock
Septic shock
What are the three stages of shock
Compensated shock
Progressive shock
Irreversible shock
When does cardiogenic shock occur most often
After a severe myocardial infarction but also may result from ventricular fibrillation
What is hypovolemic shock
The result of decreased blood volume due to hemorrhage
Other causes can be due to extreme sweating, extreme loss of water through kidneys (diuresis) or intestines(diarrhea)
What is anaphylactic shock
Allergic reaction where histamine increase capillary permeability And vasodilation. Plasma is lost to tissue spaces which decreases blood volume blood pressure and cardiac output
What is septic shock
The result of septicemia. Presence of bacteria in the blood
Inflammatory chemicals cause based dilation and loss of plasma into tissue spaces
