WEE4 4: CH 16--Microcirculation & Lymphatic

Question 1

–It is in the microcirculation where the MOST meaningful events occur—prior to and after microcirculation, the other blood vessels are simply a transport pathway.

–Gas exchange and nutrient/waste product exchange occurs between the blood in the microcirculation and the tissues.

Answer 1

KNOW

–Microcirculation primarily includes the 500 to 700 square meters (about 1/8th of a football field) of CAPILLARIES.

Question 2

the arterioles as they progressively narrow toward the capillaries—these TERMINAL arterioles are called
_____________

Answer 2

metarterioles.

Question 3

• Metarterioles have SMOOTH muscle fibers that _______ the vessels at intermittent points .

** Where the metarteriole meets the capillary, the smooth muscle fibers form the __________ sphincter which can open or close the opening of the capillary.

Answer 3

encircle

precapillary

Question 4

Because the metarterioles and the precapillary sphinters are in close contact with the tissues they serve, the _____ _______ of the tissues controls the blood flow according to tissue needs. Control of blood flow is based on increasing or decreasing the diameter of the blood vessels.

Answer 4

local conditions

Question 5

Microcirculation Structures

1. __________ ____—single celled, highly permeable layer of endothelium surrounded by a thin basement membrane.

Answer 5

Capillary Wall

Question 6

Microcirculation Structures

2. _______- between individual cells that make up the capillary wall allow for small nutrient molecules and plasma fluid to
   leave the capillary through these pores.
   • Blood cells and plasma proteins are too large to fit through the pores.

Answer 6

Pores

Question 7

Microcirculation Structures (PORES CONTINUED…)

Two small passageways:

a) __________ ______ (pores)— thin, curving channels
between cells. WATER, water- soluble ions and small solutes
can diffuse through these intercellular clefts.

b) ____________ (plasmalemmal vesiscles)—seemed to be formed on the cell membrane from PROTEINS (caveolins) associated with cholesterol and other lipid materials. They play a transcytosis role by engulfing small packets of plasma, or extra cellular fluid with plasma proteins, and transporting it slowly through the endothelium.

Answer 7

Intercellular cleft

Caveolae

Question 8

Special Types of Pores

a) _________—tight junctions only allow extremely small molecules in or out.
b) _________—opposite of brain— has large pores so that even plasma proteins can pass.
c) ___________—smaller than liver but larger than brain.
d) ____________ —contain windows called fenestrae which allow tremendous amounts of small ions, but not large plasma proteins, to pass so the kidneys can filter the blood rapidly.

Answer 8

Brain

Liver

GI Liver

Kidney

Question 9

Vasomotion

• Vasomotion is the type of blood flow through the _____________. Blood flow through these vessels is NOT continuous, it flows intermittently.
• The cause is intermittent opening and closing of metarterioles and precapillary sphincters.
• Regulation of vasomotion is primarily controlled by the ____ concentration in the tissues.
• When tissues use O2 at a greater rate, O2 concentration ↓ thus intermittent periods of flow occur more often.

Answer 9

capillaries

O2

Question 10

Exchanges between Blood and Interstitial Fluid

1. __________ is the primary method of transfer of water and dissolved ions between the capillaries and the interstitial fluid.

Answer 10

Diffusion

Question 11

Exchanges between Blood and Interstitial Fluid

2. ______ ______ is the space between cells and contains the fluid that provides a watery environment for cells.

Answer 11

Interstitial space

Question 12

Exchanges between Blood and Interstitial Fluid

3. Diffusion results from the “______ _______” of water molecules and dissolved ions as they randomly move in all directions between the capillary membrane and the interstitial fluid.

Answer 12

thermal motion

Question 13

Things that have and effect on diffusion
1. ____ ________ _________—can diffuse directly through the capillary membrane and do NOT have go through the pores.

a) these substances include O2 and CO2
b) because they can diffuse directly across the membrane, they can diffuse at a much FASTER rate than lipid-insoluble substances

Answer 13

Lipid-Soluble Substances

Question 14

Things that have and effect on diffusion

2. Water-Soluble and Lipid-Insoluble Substances—must pass through the intercellular pores (clefts) that are located between the __________ cells of the capillary membrane.
   a) these substances include water molecules, sodium ions, chloride ions and glucose

Answer 14

endothelial

Question 15

Things that have and effect on diffusion

3. Effect of Molecular Size (Weight)—permeability of capillary pores to substances of varying sizes has an effect on diffusion rate.
   a) the ______ the diameter of the molecule (water) the faster it will diffuse; intermediate diameter molecules diffuse at a slower rate
   b) ________molecules (plasma proteins) are not permeable in most organ cells but the _____ has pores large enough –thus, capillary permeability can vary depending on the function of the organ

Answer 15

smaller

larger

liver

Question 16

Things that have and effect on diffusion

4. Effect of ___________ Gradient—as with any gradient, substances will move more rapidly the greater the difference in concentration between the area of higher concentration and the area of lower concentration.

Example of O2 and CO2:
O2 is higher in the capillary blood than the interstitial fluid therefore, O2 moves from the blood toward the tissues.
Conversely, CO2 is higher in the tissue so it moves into the capillary.

Answer 16

Concentration

Question 17

Interstitium

A. Collective of _______ located between all cells in the body—makes up about 1/6th of total body volume.
B. Contains two solid structures:
1. _________ fiber bundles to provide tensile strength against cells.
2. __________ filaments are thin filaments that form a mat to provide more substance

Answer 17

spaces

Collagen

Proteoglycan

Question 18

The interstitial fluid contains similar components as plasma with the exception of a lower concentration of ________ because plasma _______ do not easily pass through the capillary pores.

Answer 18

proteins

proteins

(note: the interstitial fluid actually has a higher number of proteins but this fluid is in more quantity than plasma so the concentration of proteins is lower in interstitial fluid).

Question 19

Because of the proteoglycan filaments and the vesicles containing fluids, interstitial fluid is the consistency of a____

Answer 19

gel.

**As a result of the gel, fluids and molecules do NOT flow through the interstitial fluid, they diffuse through molecule by molecule

Question 20

Usually, there is a small percentage (< 1%) of free fluid in the interstitium, but when tissues develop _____, these rivulets of free fluid increase tremendously.

Answer 20

edema

Question 21

Filtration vs. Absorption

The blood (hydrostatic) pressure in the capillaries tends to force fluids and dissolved ions through the capillary pores into the interstitial fluid—____________.

Answer 21

Filtration

Question 22

Filtration vs. Absorption

osmotic pressure caused by the plasma proteins (colloid osmotic pressure) inside the capillary cause fluid movement by osmosis from the interstitial fluid into the blood—_____________

Answer 22

Absorption.

**The BALANCE between filtration and absorption prevents significant fluid loss from the blood into the interstitial fluid

Question 23

There are four primary forces (called ______ _______) that determine if fluid will move out of the blood into the interstitial space (filtration) or from the interstitial space into the blood (absorption).

1. Capillary pressure (Pc)—tends to force fluid OUTWARD from the blood
2. Interstitial fluid pressure (Pif)—tends to force fluid INTO the blood when Pif is (+) and OUTWARD if Pif is (-).
3. Plasma colloid osmotic pressure (Πp)—tends to cause osmosis of fluid INTO the blood.
4. Interstitial fluid colloid osmostic pressure (Πif)—tends to cause osmosis of fluid OUTWARD from blood.

Answer 23

Starling forces

Question 24

If the sum of the Starling forces (net filtration pressure—NFP) is ________, there will be a net fluid FILTRATION—from blood INTO interstitial fluid. If the sum of the Starling forces is _________, there will be a net fluid ABSORPTION from the plasma INTO the interstitial fluid

Answer 24

positive

negative

Question 25

Hydrostatic pressure (Pc) forces fluids ____ of the blood on the ARTERIOLE end of the capillary.

1. Because of the _______ concentration of plasma proteins in the blood, this creates an plasma colloid osmotic pressure (Πp) which re-absorbs water back INTO the blood via osmosis on the VENULE end of the capillary
2. The excess fluid in the interstitial fluid must be returned to blood circulation via the ________ system

Answer 25

out

higher

lymphatic

**Net filtration of fluid OUT of the capillary into the interstitial fluid is HIGHER than net absorption of fluid back into the capillary.

Question 26

Abnormal Imbalance of Forces

1. If the fluid amount is higher than what the lymphatic system can carry back to blood circulation, the concentration of fluid in the interstitial spaces causes
   _____
2. If mean capillary pressure _____, net reabsorption increases resulting in more fluid coming inward to the blood causing an increase in blood volume.

Answer 26

edema.

falls

Question 27

Lymphatic System

This system provides an accessory route for fluids to flow from the interstitial fluid back to the circulatory system.
• Most importantly, lymphatic vessels can carry ______ and other large substances back to the blood.
• Returning plasma proteins back to the blood is essential for life.

Answer 27

proteins

Question 28

Lymphatic System

Lymph vessels from the _____ part of the body empty into the thoracic duct which then empties into the venous system at the juncture of the left internal jugular vein and the left subclavian vein

Answer 28

lower

Question 29

Lymphatic System

1. Lymph from the LEFT side of the head, left arm and parts of the left thorax enters the thoracic cavity and then the two veins.
2. Lymph from the RIGHT side of the head and neck, right arm and parts of the right thorax enter the right lymph duct and then enter the venous system at the right subclavian vein and right internal jugular vein.

Answer 29

KNOW LEFT VS RIGHT

Question 30

Most of the fluid that filters out of the arteriole side of the capillaries is reabsorbed on the VENULE side of the capillary bed. However, about one-tenth of the fluid is NOT reabsorbed and enters the lymphatic capillaries and returns to the blood via the ________ vessels rather than via the venules and veins.

•The total amount of lymph made from the intersitital fluid is 2 to 3 liters per day.

Answer 30

lymphatic

Question 31

Structure of Lymphatic Capillary

1. Anchoring filaments—attached to the endothelial cells of the lymphatic capillary.
2. “_______”—the endothelial cells of the capillary overlap so that the overlapping edge can flap inward.
3. The interstitial fluid containing proteins can push the flap open allowing flow into the capillary and then the backflow closes the “________”.

Answer 31

Valve

valve

Question 32

Formation of Lymph

Lymph is originally derived from fluid

Answer 32

interstitial

Question 33

Formation of Lymph

Most tissues have a protein concentration of 2 g/dl in the interstitial fluid surrounding them. However, some organs, like the ______, have a higher protein concentration (6 g/dl).

Answer 33

liver

Question 34

Formation of Lymph

• Lymphatic vessels pick up nutrients (including ALL ______) from the digestive tract before they enter blood circulation.
• Bacteria can also enter the lymphatic vessels and as they pass through the lymph nodes, most bacteria is _______

Answer 34

lipids

destroyed

Question 35

Lymph Flow

______ Pump—the valves described earlier are used to not only trap fluids, proteins, nutrients, etc., they are used as a pump. The filling of one vessel causes it to contract and the fluid is pumped through the next valve to the next vessel—even throughout the collecting vessels.

Answer 35

Internal

Question 36

Lymph Flow

___________ Pumps
•Contraction of surrounding skeletal muscle
•Pulsation of adjacent arteries
•Movement of parts of body

Answer 36

External