Flashcards in Chapter 20 Deck (100):
Three parts of the blood vessel wall are?
Tunica interna (endothelium) - inner layer
Tunica media - middle layer
Tunica externa- outer layer
This layer lines the inside of the vessel
This layer is simple squamous epithelium overlying a basement membrane
This layer Is a selectively permeable barrier to materials entering or leaving the bloodstream
This layer is made of smooth muscle, collagen and elastic tissue
This layer strengthens the vessel and changes the diameter of the blood vessel
This layer is made of loose connective tissue
This layer anchors the vessel and provides passage for small nerves, lymphatic vessels and smaller blood vessels
Small blood vessels called vasa vasorum supply blood to the outer wall of larger vessels
These carry blood away from the heart
There are three types of arteries, what are they?
Conducting (elastic or large) arteries
Distributing (muscular or medium) arteries
Resistance (small) arteries
The aorta, pulmonary trunk, Common iliac, common carotid, and subclavian arteries, are what type of arteries?
- These arteries are smaller branches that distribute blood to specific organs
- There Tunica media has layers of smooth muscle allowing vasomotion
- Small arteries, the smallest are arterioles (constriction going on)
- Short vessels that link arterioles and capillaries
- Each forms a pre-capillary sphincter, which is smooth muscle that encircles the entrance to one capillary and can shut off
blood through the capillary bed
A weak point in an artery or in the heart wall is called a?
These exchange vessels, they are called?
There are three types of capillaries, what are they?
Sinusoids (discontinuous capillaries)
- These capillaries are endothelial cells from a continuous tube
- They're found in most tissues
- Small solutes pass-through, but larger particles are held back
- In the brain blood vessel cells are tightly joined in and form the blood brain barrier
- They have pericytes, which are cells with tendrils that wrap around capillaries and regulate permeability, they contribute to
growth and repair
- Cells that have filtration pores
- These pores allow rapid passage of small molecules, but retain larger molecules
- They are found in the kidneys, endocrine glands, small intestine and choroid plexus
- Irregular blood-filled spaces
- Found in the liver, bone marrow and spleen
- Endothelial cells are separated by wide gaps so blood cells and proteins can pass through
- Capillaries are organized into networks called these?
- 10-100 capillaries supplied by single metarteriole
- metarteriole Continues as a thoroughfare channel and leads to a venule
- Capillaries branch off proximal end and empty into the distal end
- When sphincters are closed, blood bypasses the capillaries and flows through the thoroughfare channel to the venule
- These carry blood back to the heart, what are they?
- expand easily to accommodate increased blood volume
- low blood pressure, about 10 mm Hg
There are five types of veins, what are they?
- These are small veins that receive blood from capillaries
- They are porous and also exchange fluid
- These receive blood from postcapillary venules
- Contain one or two layers of smooth muscle
- Infolding of their tunica interna form venous valves
- Valves keep the blood from dropping down with the pool of gravity
- Veins with thin-walls, large lumen and no smooth muscle
- They have smooth muscle in all three tunics
- Venae cavae, pulmonary, internal jugular, and renal veins
The flow of blood back to the heart is achieved by five mechanisms, this process is called?
These Allow blood to flow in only one direction?
There is a venous pressure gradient from venules to the heart favoring the flow of blood to the heart, this is called?
Blood from the head and neck returns to the heart by flowing down through large veins, this is called?
In the limbs, the veins are surrounded by muscles which squeeze the blood out of the vein when the muscles contract, this is called?
Skeletal muscle pump
When you inhale the thoracic cavity pressure drops and the abdominal cavity pressure raises putting pressure on the abdominal inferior vena cava and creating a pressure gradient toward the heart, this is called?
Thoracic (respiratory) pump
During ventricular systole, the atria enlarge creating a slight suction, This is called?
When blood pools in the lower limbs, stretches the veins, and pulls the venous valves apart until the Valves cannot prevent back flow of blood, wall of vein becomes weak developing into a regular dilations, this is called?
What is the simplest and most common route of blood flow?
Heart- arteries- arterioles - capillaries - venules - veins - heart
There's the simple pathway which is the most common circulatory route but there are exceptions, name four of them.
When blood flows through two capillary beds before returning to the heart, this is called?
When blood flows from artery to vein by bypassing capillaries, this is called?
When veins that interconnect provide alternate routes, this is called?
Went to arteries merge an organ to provide alternate route, this is called?
The amount of blood flowing through an organ, tissue, or blood vessel in a given time (mL/min), is called what?
The flow per given volume or mass of tissue (mL/min/g), is called what?
The physical principles of bloodflow are based on two things, what are they?
Pressure (causing flow)
Resistance (preventing flow)
The force that the blood exerts against a vessel wall is called what?
Blood pressure is measured with this it is connected to an inflatable cuff . The pressure in cuff is greater than the pressure in blood vessel, cuts off blood and then slowly releases, what is this Instrument called?
Where is blood pressure recorded from?
The brachial artery
What are the five different pressures that we look at?
Arterial blood pressure
Mean arterial pressure
What is the peak arterial blood pressure occurring during Ventricular contraction (120mmHg)?
The minimum arterial blood pressure occurring during ventricular relaxation, between heartbeats (75mmHg)?
Systolic pressure divided by diastolic pressure (Systolic pressure/Diastolic pressure)
Arterial blood pressure
Systolic pressure - Diastolic pressure
(The maximum stress exerted on small arteries by the pressure surges generated from the heart)
Diastolic pressure + 1/3 Pulse pressure
(Measure of stress on blood vessels)
Mean arterial pressure (MAP)
Chronic resting blood pressure higher than 140/90
Chronic low resting blood pressure
Does the blood flow in the arteries pulsate?
Blood flows in the capillaries and veins at a steady speed (with or without) pulsation?
Why does blood pressure rise with age?
Because of arteriosclerosis and atherosclerosis
What is blood-pressure determined by?
Cardiac output, blood volume and resistance
What is the opposition to flow that the blood encounters in blood vessels?
Peripheral resistance hinges on three variables, what are they?
- Thickness of the blood
- Deficiency of red blood cells or albumin reduces viscosity and speeds up bloodflow (decreases resistance)
- Polycythemia or dehydration increases viscosity and slows down bloodflow (increases resistance)
- The farther a liquid travels thru a tube, the more cumulative friction it encounters, thus pressure and flow drop with distance (increases resistance)
- The only significant way of controlling peripheral resistance from moment to moment is by vasomotion which is adjusting the
radius of the blood vessels.
- vasomotion includes:
-vasoconstriction- Narrowing of a vessel when smooth muscles contract (increases Resistance)
-Vasodilation - Widening of a vessel when smooth muscles relax
- When the vessel dilates more blood is in the middle of the blood stream and the flow is faster, while when the vessel
constricts, more of the blood is close to the wall and the flow is slower
- Vessel radius markedly affects blood velocity
- From a order to capillary, velocity Diminishes
There are three ways of controlling blood pressure and flow, what are they?
What is the ability of tissues to regulate their own blood supply?
What does hypoxia and accumulation of waste products in tissue do?
They stimulate vasodilation which increases perfusion
What do platelets, endothelial cells and perivascular tissue do that stimulate vasomotion?
They secrete vasoactive chemicals
Over time hypoxic tissue can increase it's own perfusion by what?
In addition to local control, the blood vessels are under remote control by what?
by the central and autonomic nervous system's (neural control)
The vasomotor center is an integrating center for three autonomic reflexes, what are they?
Medullary ischemic reflex
Exerts SNS control
The SNS stimulates most blood vessels to constrict which increases blood pressure
The SNS dilates blood vessels of skeletal and cardiac muscles
Vasomotor center of medulla oblongata
This is the autonomic nervous system's response to changes in blood pressure
When blood-pressure rises, increasing nerve signals inhibit the vasomotor center and stimulate the cardio inhibitory neurons, this decreases Heart rate, cardiac output, and blood pressure
When blood pressure drops the reverse occurs and blood-pressure rises back to normal
This is The autonomic nervous system response to changes in blood pH, O2, and CO2
Hypoxemia, Hypercapnia (high CO2), and acidosis (high hydrogen) stimulate chemoreceptors and act through the vasomotor center to induce vasoconstriction
Increases overall blood pressure, increasing perfusion of lungs and rate of gas exchange
The autonomic nervous system's response to a drop in perfusion of brain
Drop in perfusion stimulates the cardiac and vasomotor centers to increase heart rate and widespread vasoconstriction
These actions raise the blood pressure and blood perfusion through the brain
Medullary ischemic reflex
There are five hormones under hormone control that influence blood pressure, what are they?
Epinephrine and norepinephrine
A potent vasoconstrictor that raises blood pressure
Promotes sodium retention by the kidneys and water follows
It increases the blood volume and blood pressure
Secreted by the heart and brain to antagonize aldosterone
These increase sodium excretion by the kidneys
These Reduce blood volume and blood pressure
They are used to lower high blood pressure
Promotes water retention
Pathologic, at high concentrations it is a vasoconstrictor
Antidiuretic hormone (Vasopressin)
The stimulate vasoconstriction and raise blood pressure in most blood vessels, in cardiac and skeletal muscle blood vessels, they stimulate vasodilation to increase bloodflow (fight or flight)
Epinephrine or norepinephrine
A two-way movement of fluid is called what?
Movement because molecules are more concentrated in blood and tissue fluid or the reverse, is called?
Diffusion, filtration and reabsorption are three types of what?
Filtration and reabsorption
Pushes fluid out
Draws fluid out
Draws fluid in
Draws fluid out
Blood hydrostatic pressure
Interstitial hydrostatic pressure
Blood colloid osmotic pressure
Tissue fluid colloid osmotic pressure
Prevailing force is outward ( filtration)?
Prevailing force is inward (reabsorption)?
More is filtered out then reabsorbed?
Accumulation of excess fluid in tissue
Kidney failure, hypertension, histamines
Increased capillary filtration
Hypoproteinemia from liver disease, dietary protein deficiency, severe burns
Reduced capillary reabsorption
Surgical removal of nodes
Obstructed lymphatic drainage
Cardiac output is insufficient to meet the bodies needs?
Inadequate pumping of the heart?
Loss of blood volume as a result of hemorrhage, trauma, bleeding ulcers, burns or dehydration?
Tumor, etc. compresses a vein and impedes it's bloodflow?
Obstructed venous return shock
Too much blood accumulates in the lower body?
Venous pooling shock
Sudden loss of vasomotor tone?
Bacterial toxins trigger vasodilation and increased capillary permeability?
Ag-Ab Complexes trigger release of histamine
Brief episodes of cerebral ischemia which may result from spasms of diseased cerebral arteries?
TIA (transient ischemic attack)