Chapter 10

Human Physiology

Draw blood vessel anatomy diagram

Draw blood vessel anatomy diagram

The ___ tree consists of arteries, arterioles, capillaries, venules, and veins.

vascular

The systemic and pulmonary circulations each consist of a ___ system of vessels.

closed

___ are the network of tubes through which blood is pumped around the body

vessels

___ are vessels that carry blood towards the heart

veins

___ (pressure reservoir) carry blood away from the heart to the tissues. They branch into a tree of progressively smaller vessels.

Arteries

This smaller progression of arteries forms ___ near an organ. Regulation of the diameter of arterioles supplying an organ adjusts the volume of blood sent to that organ

arterioles

Arterioles branch into ___, the smallest vessels. They are the microscopic exchange vessels with all cells, offering blood that supplies the metabolic needs of the cells

capillaries

Capillaries merge into ___ that send blood into small veins. They form progressively larger veins. Venules and veins (fluid reservoir) return blood to the heart.

venules

Draw blood vessels big to small diagram

Draw blood vessels big to small diagram

The ___ is the pressure difference between the beginning and end of a vessel.

pressure gradient

Blood flows from an area of ___ pressure to an area of __ pressure (pressure gradient)

Higher; lower

___ is the opposition to blood flow through a vessel. It depends on three factors: blood viscosity, vessel length, and vessel radius.

Resistance

The major determinant to resistance to blood flow is the ___ of a vessel. A slight change in radius produces a significant change in blood flow. The blood flow arterioles are highly affected by this relationship. It is expressed by the equation: R ~(is proportional to) 1/r⁴

radius

The flow rate (F) of blood through a vessel is directly proportional to the pressure gradient (P) and inversely proportional to vascular resistance (R).

F = ∆ P/R

Blood pressure is measured by a ___ on an artery. Its cuff is wrapped around the upper arm.

sphygmomanometer

When the pressure in the cuff of the sphygmomanometer is greater than the ___, blood flow is blocked through the vessel. At this time no sound is heard through a stethoscope placed over the brachial artery at the inside of the elbow.

brachial artery

When the pressure in the cuff is slowly released, it will fall just below ___ pressure. This creates vibrations and sound. The first heart sound indicates ___ pressure (ex, 120 mm Hg; peak pressure).

systolic

When the falling cuff pressure drops below ___ pressure, the vibrations and sound disappears. This indicates ___ pressure (80 mm Hg; lowest pressure).

diastolic

The ___ is the difference between the systolic and diastolic pressures (120 mm Hg - 80 mm Hg = 40 mm Hg).

pulse pressure

Draw diastolic vs systolic pressure graph

Draw diastolic vs systolic pressure graph

A ___ is the main driving force producing a flow of blood.

mean arterial pressure

mean arterial pressure = diastole pressure + 1/3 the pulse pressure; ex: 80 +1/3 (40) = 93; This average is weighted, as about two-thirds of the ___ is spent in diastole

cardiac cycle

Draw mean arterial pressure graph

Draw mean arterial pressure graph

___ is the total resistance offered by all the systemic peripheral vessels together. The greatest percentage of the ___ is due to arteriolar resistance, because arterioles are the primary resistance vessel.

total peripheral resistance (TPR)

Blood pressure is regulated by cardiac output and total ___ resistance. Equation: 

mean arterial pressure = cardiac output x total ___ resistance

peripheral

___ depends on heart rate x stroke volume

Cardiac output

___ depends on autonomic control plus some hormone signaling.

Heart rate

___ depends on sympathetic stimulation. It also increases by venous return

Stroke volume

___ depends on several factors such as venous vasoconstriction and the skeletal muscle pump.

Venous return

Draw Factors influencing mean arterial blood pressure diagram

Draw Factors influencing mean arterial blood pressure diagram

___ is the term applied to such narrowing of a vessel. Happens when the smooth muscle layer contracts, causing the vessel’s circumference (and its radius) to become smaller, increasing resistance and decreasing flow

vasoconstriction

___ refers to enlargement in the circumference and radius of a vessel as a result of its smooth muscle layer relaxing. This leads to decreased resistance and increased flow through that vessel.

vasodilation

Total peripheral resistance depends on the ___ of arterioles plus blood viscosity 

radius

The radius size of arterioles depends on ___ stimulation to said arterioles and local metabolic/chemical controls. It is also controlled by several hormones.

sympathetic

Arteriole radii change by ___ (narrowing) and __ (enlargement). To produce these changes their thick, middle layer of smooth muscle is subject to neural, hormonal, and local chemical control.

Vasoconstriction; vasodilation

Effectiveness of circulating ___ influences the ___  returning to the heart. This returning ___ depends on capillary exchange which in the long term means controlling salt and water balance.

Blood volume

Mean arterial pressure is ___ by long-term and short-term measures.

controlled

Extrinsic ___ signaling controls arteriolar radii. This signaling regulates blood pressure. ___ neurons supply the smooth muscle in the walls of most arterioles.

sympathetic

___ sympathetic signaling produces generalized arteriolar vasoconstriction. This increases the total peripheral resistance

increased

Mean arterial pressure (MAP) = ___ x TPR

cardiac output

As the TPR increases, the mean arterial pressure increases by direct proportion. The increase in TPR is a generalized increase. Many arterioles constrict to produce this effect, increasing the MAP. Organs supplied by these constricting vessels receive ___ blood flow.

less

The increase in TPR is a generalized increase. However, some arterioles serving organs (e.g., skeletal muscles during exercise) dilate during this increase in TPR. These organs receive ___ blood as the MAP increases.

more

Local control of ___ determines the distribution of the cardiac output.

arteriolar resistance

The driving force for blood flow is identical to all organs, However, differences in arteriolar resistance varies between ___. This determines the distribution of blood they receive.

organs

Blood flow to an organ can vary by the change in ___ in arterioles serving it. For example, during exercise more blood flow is shifted to the skeletal muscles. Less flows to the digestive tract. In this case the arterioles to the skeletal muscles dilate, offering less ___. The arterioles serving the digestive tract constrict.

resistance

___ is muscle-produced, nerve independent contractile activity

myogenic activity

Local ___ influences on the resistance of arterioles include local metabolic changes and histamine release.

chemical

Local ___ influences include local heat and cold and myogenic responses to stretch.

physical

Draw diagram of total blood flow

Draw diagram of total blood flow

___ are the sites of exchange between the blood and body cells. This exchange is accomplished mainly by diffusion. They are very abundant, offering a large surface area to serve cells. This process is enhanced by the thin walls and narrow openings of ___, plus their branching.

capillaries

The blood through capillaries is ___ due to the tremendous cross-sectional area of all capillaries in an area. To explain, it is like a wide river spitting into millions of small streams. The river, while it was larger, had 100 meters for the water to rush in, while the streams add up to 1000 meters. More space means that there is less water flowing through the stream given the increase in area, explains the ‘slow’ movement.

slow

The slow blood flow of capillaries enhances the opportunity for ___.

diffusion

Compared to arterioles, the resistance offered by capillaries is ___ due to the large cross-sectional areas of these microscopic vessels. Even if the vast majority of the capillaries have high resistance, together they have ___ resistance because of their sheer pulled together size (total cross sectional area)

low

A ___ is a split, fissure, or opening in a structure

cleft

Capillaries have ___ & water-filled clefts in their walls. The ___ allow the passage of small, water-soluble substances such as ions, glucose and fluid.

pores

 Lipid-soluble substances dissolve through the lipid bilayer in the ___ in the capillary wall.

endothelial cells

___ are impermeable junctions that join the lateral edges of epithelial cells near their luminal borders, thus preventing movement of material between the cells

Tight junctions

Tight junctions connecting the walls of capillary cells in the ___ form a blood-brainbarrier. This blocks transport

brain

___ increases capillary permeability.

Histamine

Draw capillaries pores diagram

Draw capillaries pores diagram

Draw capillaries anatomy diagram

Draw capillaries anatomy diagram

A ___ is a ring of smooth muscle around the entrance to a capillary

sphincter

___ refers to the microscopic region just before a capillary, i.e. the exact points where capillaries branch off from larger vessels

precapillary

Under resting conditions many capillaries ___.

do not open

Precapillary sphincters surround capillaries. The ___ of these sphincters reduces the blood flowing into the capillaries in an organ, like a valve

contraction

The ___ of these sphincters (e.g., an exercising skeletal muscle) increases the blood flowing into the capillaries in an organ

relaxation

A ___ is a continuous, direct blood vessel pathway within the microcirculation system that connects an arteriole directly to a venule

thoroughfare channel

___ is the initial, proximal segment of the thoroughfare channel. It contains smooth muscle fibers that can constrict to limit blood entering the capillary network

metarteriole

Some capillaries have a ___ or thoroughfare channel from an arteriole to a capillary.

metarteriole

Draw sphincters closed v open diagram. Read along p.363-365 for deeper understanding

Draw sphincters closed v open diagram. Read along p.363-365 for deeper understanding

The ___ is a passive intermediary between the blood and tissue cells.

interstitial fluid

__% of the ECF is blood plasma. __% percent of the ECF is interstitial fluid. This fluid bathes the tissue cells and is where these cells exchange materials with the ECF.

20; 80

Exchange between the interstitial fluid and plasma ___ of tissue cells can be active (e.g., active carrier-mediated transport) or passive (e.g., diffusion).

membranes

Exchange across the ___, between the plasma and interstitial fluid, is largely passive

capillary wall

Diffusion across the capillary walls is important in ___ exchange (e.g., gases).

solute

Only the passage (across capillary walls) of ___ is limited.

plasma proteins

___ Is the process in which a volume of protein-free plasma actually filters out of the capillary, (volume of protein-free plasma) mixes with the surrounding interstitial fluid, and then is reabsorbed. The various constituents of the fluid are moving together in built, or as unit, in contrast to discrete diffusion of individual solutes

Bulk flow

Some substances cross the ___ wall by bulk flow. Constituents in a fluid move through in bulk. For example, fluid moving inside a capillary can be pushed through the wall to the outside of the capillary (from higher fluid pressure to lower fluid pressure)

capillary

Four types of Capillary Transport Mechanisms: Diffusion (Direct, Intercellular cleft, Fenestration),  Vesicles

Four types …

___ are the large 20-100nm holes that extend through the thickness of the endothelial cells themselves. They are important in rapid movement of fluid across the capillaries in these organs (kidneys and intestine) during the formation of urine during the absorption of digestive meal.

fenestrations

Draw Capillary Transport Mechanisms Diagram. Read p.363-364 for more info

Draw Capillary Transport Mechanisms Diagram. Read p.363-364 for more info

A ___ of fluid occurs across the capillary wall

net exchange

___ is the process fluid being pushed out through a capillary’s pores. At the arteriolar end of the capillary the outward pressure (outside the capillary) is greater than the inward pressure, forcing fluid out

Ultrafiltration

At the venular end of the capillary the inward pressure is greater than the outward pressure. The outward pressure has dropped due to a drop of blood pressure at this end compared to the arteriolar end. ___ occurs

Reabsorption

Both ultrafiltration and reabsorption occur by ___. Fluid moves by a passive process. This is not important in the exchange of individual solutes between the blood and tissue cells, as very few solutes move across capillary walls by ___.

bulk flow

Bulk flow does regulate the distribution of fluid between the two regions of the ECF, the ___ and __. Fluid shifts between these two regions compensate for changes to this distribution (e.g., excessive fluid intake can expand the plasma volume)

blood plasma; interstitial fluid

Draw ultrafiltration and reabsorption diagram. Read p.366 for more info

Draw ultrafiltration and reabsorption diagram. Read p.366 for more info

___ is the pressure exerted by fluid on the walls that contains it

hydrostatic (fluid) pressure

A ___ is a mixture where microscopically tiny particles of one substance are suspended throughout another substance. The particles are larger than molecules but small enough not to settle out.

colloid

___ is the osmotic force across the capillary wall resulting from the uneven colloidal dispersion of plasma proteins between the blood and interstitial fluid

colloid osmotic pressure

Bulk flow occurs by the difference in hydrostatic (fluid) and colloidal osmotic pressures between the ___ and interstitial pressures.

plasma

Capillary blood pressure is the hydrostatic pressure exerted on the inside of capillary walls by the ___. This forces fluid out of the capillaries (the outward pressure)

blood

The blood plasma-colloid pressure encourages fluid movement into the capillaries (the inward pressure). The blood plasma has a higher ___ concentration compared to the interstitial fluid. This produces a water concentration difference. Water enters the blood plasma from the interstitial fluid by osmosis. Read p.366 cause its way too damn hot for me to be summarizing and thinking

protein

The ___-hydrostatic pressure is the pressure exerted on the outside of the capillary wall by the ___. It has a small value.

 interstitial fluid

The interstitial fluid-___ is also insignificant in most cases, as plasma proteins normally remain in the blood plasma.

colloid osmotic pressure

Draw Forces for Fluid Flows in Capillaries diagram

Draw Forces for Fluid Flows in Capillaries diagram

Draw Factors facilitating venous return diagram

Draw Factors facilitating venous return diagram

The ___ reflex is a short-term mechanism for regulating blood pressure.

baroreceptor

Baroreceptors are found in the ___ and aortic arch. These receptors are sensitive to fluctuations in pulse pressure. Look up where that is

carotid sinus