Chapter 21 EXAM Flashcards
The smallest arterial branches are __ and from there blood moves into ____.
Arterioles
Capillaries
What takes place at the capillaries?
Diffusion between blood and interstitial fluid
From capillaries, blood enters sm ___ which unite to form larger ____ and return blood to the heart.
Venules
Veins
What are the 3 layers in a blood vessel?
Tunica intima
Tunica media
Tunica externa
The tunica intima is the inner layer of a vessel. It is made up of what fibers?
Endothelial lining and surrounding layer of connective tissue
In arteries, the outer margin of the tunica intima contains a thick layer of elastic fibers called what?
Internal elastic membrane
The ___ ___ is the middle layer of a vessel and is made up of concentric sheets of smooth muscle tissue in a framework of loos connective tissue.
Tunica media
The external elastic membrane separates what?
The tunica media fr the tunica externa
The tunica extrerna is the outer layer of a vessel that forms what?
Connective tissue sheath
In ____, the tunica externa contains collagen fibers w/scattered bands of elastic fibers
Arteries
In ___, the tunica externa is generally thicker than the tunica media & contains networks of elastic fibers & bundles of smooth muscle cells.
Veins
T or F: The walls of arteries & veins are too thick to allow diffusion.
True
What are vasa vasorum?
Sm arteries & veins that supply smooth muscle cells & fibroblasts of tunica media & tunica externa in lg vessels
Which contains more smooth muscle and elastic fibers; an artery or a vein?
Artery
When a/an ____ constricts its endothelium is thrown into folds giving it a pleated appearance.
Artery
What is it in a vain that prevents backflow of blood into the capillaries?
Valves
Vasoconstriction of arterial smooth muscle is caused by stimulation of what division of the ANS?
Sympathetic division
What 3 things about the circulatory sys do vasoconstriction or vasodilation affect?
Afterload on the heart
Peripheral BP
Capillary blood flow
Elastic arteries are also known as conducting arteries. Why?
B/c they carry lg vols of blood away from the heart
What happens to BP & elastic arteries during ventricular systole?
BP rises & arteries expand as stroke vol is ejected
What happens to BP & elastic fibers during ventricular diastole?
BP falls & arteries return to their original size
What is the name given to arteries that distribute blood to the bodies skeletal muscles and internal organs?
Muscular or distribution arteries
Superficial arteries are important as ___ ___.
Pressure Points
When local arterial pressure exceeds the capacity of elastic components of the tunics an ___ occurs.
Aneurysm
What are the 3 components of a fenestrated capillary?
Pores
Endothelial cells
Basement membrane
What are the 2 components of a continuous capillary?
Endothelial cells
Basement membrane
What 3 components make up and arteriole?
Smooth Muscle
Endothelium
Basement membrane
What are the 2 components of a venule?
Tunica externa
Endothelium
What are the only vessels that allow for exchange between blood and surrounding interstitial fluid?
Capillaries
Which capillaries have the following characteristics:
- In all tissues except epithelia & cartilage
- Permit water, sm solutes & lipid soluble
material to diffuse into interstitial fluid
- Prevent loss of blood cells & plasma proteins
Continuous Capillaries
What is bulk transport?
Mvmt of materials by endo- or exocytosis at the inner endothelial surface
___ ___ contain windows or pores that penetrate the endothelial lining,
Fenestrated capillaries
What is the purpose of the pores on fenestrated capillaries?
Rapid exchange of water & solutes between plasma & interstitial fluid
____ resemble fenestrated capillaries that are flattened and irregular shape.
Sinusoids
What type of capillary has the following characteristics:
- Gaps between adjacent endothelial cells
- Thin or absent basement membrane
- Permit free exchange of water & solutes as lg
as plasma proteins
Sinusoidal Capillaries
____ function not as individual units but rather as part of an interconnected network called a bed or plexus.
Capillaries
What do capillaries empty into?
Venules
The entrance to each capillary is guarded by what?
Precapillary sphincter
The passageway that forms the entrance to capillaries fr arterioles or the exit to venules is known as what?
Metarteriole or precapillary arteriole
In between metarterioles, are passageways that resemble typical capillaries in structure and are called what?
Thoroughfare channels
More than one artery may supply a capillary bed. The multiple arteries are known as ___.
Collaterals
The fusion of 2 collateral arteries that supply a capillary bed is an example of ___ ___.
Arterial anastomosis
___ ___ are direct connections between arterioles and venues.
Arteriovenous Anastomoses
What occurs when an arteriovenous anastomoses are dilated?
Blood bypasses the capillary bed and flows directly into venous circulation
The pattern of blood flow through an arteriovenous anastomoses is regulated by ___ innervation under the ctrl of the cardiovascular centers of the ___ ___.
Sympathetic
Medulla Oblongata
What is angiogenesis and what directs it?
Formation of new blood vessels
Vascular endothelial growth factor (VEGF)
The cycling of contraction & relaxation of smooth muscles that changes blood flow through capillary beds is called ____.
Vasomotion
What controls vasomotor?
Changes in concentrations of chemicals & dissolved gasses in interstitial fluids
The smallest venous vessels w/an internal diameter of 20 um are ___.
Venules
Medium-sized veins are comparable to ___ ___ ranging in size fr __ - __ mm.
Muscular arteries
2-9mm
___ ___ include the superior & inferior venae cavae & their tributaries within the abdominopelvic & thoracic cavities.
Large veins
What are valves?
Folds of tunica intima that prevent backflow in the venous system
Define venous return.
Rate of blood flow back to the heart
The relationship between the vol of blood contained in a vessel and BP is known as what?
Capacitance of a blood vessel
Vessels which expand easily & can accommodate lg changes in blood vol are known as ___ vessels.
Capacitance
The constriction of veins in what 3 organs can redistribute a significant portion of blood vol?
Liver
Skin
Lungs
The amt of blood that can be shifted fr veins in the liver, skin and lungs to general circulation is called the ___ ___.
Venous reserve
Describe a pressure gradient as it relates to blood vessels.
The difference in pressure fr one end of the vessel to the other
What term is given to BP within the capillary walls?
Capillary hydrostatic pressure
Venous pressure is what?
BP within the venous system
What term describes the resistance of the entire cardiovascular system?
Total Peripheral Resistance
What 3 factors affect the total peripheral resistance?
Vascular resistance
Blood Viscosity
Turbulence
What 2 factors affect vascular resistance?
Vessel length
Vessel diameter
___ is the resistance to flow caused by interactions among molecules and suspended materials within a liquid.
Viscosity
High flow rates, irregular surfaces & sudden changes in vessel diameter upset smooth blood flow by creating eddies & swirls. This phenomenon is know as what?
Turbulence
The vol of blood flowing per unit of time through a vessel or grp of vessels is know as what?
Blood flow
The hydrostatic pressure in the arterial system is called ___ ___.
Blood Pressure
The term describing the pressure difference between the base of the ascending aorta & the entrance to the right atria is ___ ___.
Circulatory pressure
Define hydrostatic pressure.
Pressure exerted by a liquid in response to an applied force
Define peripheral resistance.
The resistance in the arterial system
As arteries branch their total cross sectional area increases affecting BP how?
Causing it to fall rapidly
As the total cross-sectional area of the vessels increases from the aorta toward the capillaries the velocity of blood flow does what?
Decreases
The peak BP measured during ventricular systole is called ___ ___.
Systolic pressure
The minimum BP at the end of ventricular diastole is called ___ ___.
Diastolic pressure
Pulse pressure is the difference between what and what?
Systolic and Diastolic pressure
How do we calculate mean arterial pressure?
Add 1/3 of the pulse pressure to diastolic pressure
What is the effect of HTN on the heart?
Increases workload
Ventricular enlargement
Greater demand for O2
Possible ischemia
As systolic pressure climbs arterial walls stretch to accommodate ventricular systole but when diastole begins, BP falls & arteries recoil. This phenomenon is called what?
Elastic rebound
Explain respiratory pump.
Changes in thoracic pressure due to inhalation and exhalation assists in moving blood in the venous system
Define diffusion.
Net mvmt of ions or molecules fr an area of higher concentration to an area of lower concentration
What are 3 variables that make diffusion occur most rapidly?
Short distances
Lg concentration gradient
Ions or molecules are small
___ is the removal of solutes as a solution flows across a porous membrane.
Filtration
What occurs during capillary filtration?
Water & sm solutes are forced across a capillary wall leaving larger solutes & suspended proteins in the blood stream
Filtration takes place at what part of a capillary and why?
Primarily at the arterial end b/c hydrostatic pressure is highest
The term used to describe the diffusion of water across a selectively permeable membrane is what?
Osmosis
The presence of suspended proteins that cannot cross capillary walls creates an osmotic pressure called __ __ __ pressure.
Blood Colloid Osmotic
What are the 4 functions of the mvmt of water out of capillaries, through peripheral tissues & back in bloodstream via lymphatic sys?
- Constant comms between plasma & interstitial fluid
- Accelerates distribution of nutrients, hormones, dissolved gasses
- Transport of insoluble lipids & tissue proteins that can’t cross capillary walls
- Flushing action that carries bacterial toxins & other chemicals
What is net hydrostatic pressure?
Difference between pressure inside capillary walls & hydrostatic pressure
Net ___ ___ pressure tends to push water & solutes out of capillaries & into interstitial fluid.
Capillary Hydrostatic
What does net capillary colloid osmotic pressure do to water & solutes?
Tends to pull them into a capillary fr interstitial fluid
The net filtration pressure (NFP) is the different between what and what?
Net hydrostatic pressure and net osmotic pressure
When net filtration pressure is positive what will fluid tend to do?
Move out of capillaries into interstitial fluid
When net filtration pressure is negative what will fluid tend to do?
Move into capillaries (reabsorption)
