Theme 1: Inside & Outside

Define total body water in terms of intracellular fluid volume and extracellular fluid volume.

Total body water = intracellular volume + extracellular volume

Explain why lymph and interstitial fluid are essentially identical in composition.

- Because there is no filtering, whatever substances are in the interstitial fluid are picked up by the lymph vessels. - therefore lymph and interstitial fluid have the same composition.

Describe the barrier that confines blood within the cardiovascular system.

- Blood is separated from interstitial fluid by a boundary layer of endothelial cells, which form the innermost layer of all the blood vessels. - they also form the innermost layer of the chambers of the heart - endothelial cells are exposed to blood on one side, and interstitial fluid on their other side.

Define and distinguish between interstitial fluid, plasma, lymph, and transcellular fluid. State how these four fluid types are related to extracellular fluid

- Interstitial fluid: the extracellular fluid in the interstitial spaces (spaces between tissue cells). Make up 1/4th of the body's totally fluid. - plasma: the liquid portion of blood, and is extracellular. - lymph: excess interstitial fluid that drains into tiny lymphatic capillaries - transcellular fluid: several small fluid compartments in the body that enclosed in transcellular spaces. (I.e. eyeballs). Relation to extracellular fluid: Extracellular fluid = interstitial fluid volume + plasma + lymph + transcellular fluid.

State the role of epithelial cells as an important body boundary layer

- It is the first great divide : epithelium separates "outside the body" from "inside the body" - Epithelial cells of the skin form a boundary layer that separates the outside of the body from the inside

Identify circumstances in which plasma proteins and leukocytes do cross the vascular endothelium, and describe how they manage to "squeeze" through the gaps between endothelial cells; define diapedesis and extravasation.

- The size and gaps between adjacent endothelial cells is the main feature that determines which substances can pass between blood and interstitial fluid and which cannot. - the structure of the endothelium is not fixed, it highly complex and adaptable - they respond and adapt to changing local conditions (i.e. in response to tissue injury) - the endothelial gaps widen enough to allow plasma proteins to escape into the interstitial fluid, and even leukocytes Extravasation: "exiting the vessels" Diapedesis: "walking across" ** both are the process of leukocytes squeezing through the endothelial junction

Explain how excess interstitial fluid gets into the lymph system.

- excess interstitial fluid drains into tiny lymphatic capillaries, which form a mesh work around the cells in most tissues of the body. - the walls of the lymphatic capillaries are composed of a single cell layer of endothelial cells, something like the walls of blood vessel capillaries - the difference is that there are relatively large gaps or clefts between the endothelial cells in the walls of lymphatic capillaries. - when fluid drains, there is no selective filtering or screening.

Explain why it is false to say that blood is an extracellular fluid.

- it is separated from interstitial fluid by a layer of endothelial cells

State the location and two primary roles of hemoglobin.

- red blood cells contains the red-pigmented protein hemoglobin, which functions as the primary carrier of O2 in the blood - it is also a significant carrier of O2 - Oxygenated hemoglobin has a bright red appearance and when oxygen is released it becomes reduced hemoglobins and becomes a darkish bluish red.

Define transcellular fluid and list several sites in the body where it is found.

- several small fluid compartments in the body are enclosed in the so-called transcellular spaces. - examples are fluid inside the eyeballs, and pockets of synovial fluid in the joint spaces, and CSF - This amount is very ve3ry small, and is ignored normally when calculating ECF.

Explain how hematocrit is determined in the clinic and state why hematocrit is sometimes called packed cell volume.

- the cellular and liquid components of blood can be separated by centrifugation. - ECF is lighter than the cells and therefore ends up on the top of the centrifuge tube while the cels end up on the bottom of the tube. - Because centrifugation results in a packing of the blood cells in the bottom of the tube, hematocrit is sometimes called the packed cell volume.

Define and distinguish between intracellular fluid and extracellular fluid, and state 2 names for the biological structure that separates the body's intracellular and extracellular compartments.

- the inside of the body is separated into two great parts: the cells and all the stuff inside them, and all the stuff that is inside of the body but outside of the cells. - Intracellular: a substance that is inside a cell - Extracellular: a substance that is inside the body but outside of the cell - Cellular membrane/plasma membranes: are the boundaries that divide the intracellular compartment from the extracellular compartment.

Explain why, from a physiologist's point of view, the contents of the gastrointestinal tract and the air in the lung's alveoli are considered to be on the outside of the body.

- the inside of the gastrointestinal tract is outside of the body. - the tract is lined with epithelial cells, therefore only when water or something is absorbed through the epithelial layers is that content inside of the body. - air in the inside of the airways and alveoli have not technically entered the body yet - the airways and alveoli are lined with a layer of epithelial cells (which is continuous with he skin) - only when the O2 has passed into and through the alveolar epithelial cell layers foes it truly enter inside the body

List the major constituents of normal blood and distinguish between those that are cellular and those that are non-cellular (extra-cellular).

- the liquid portion of blood is called plasma (ECF) (non-cellular) - the cellular portion of blood includes: red blood cells (erythrocytes), white blood cells (leukocytes), and specialized fragments called platelets (thrombocytes). - the cells contains the intracellular fluid

State which components of blood can easily cross the vascular endothelium and which cannot.

- the plasma electrolytes can diffuse quite readily across the capillary walls (through tiny gaps or pores that exist between the endothelial cells) - plasma proteins are too large to squeeze through the capillary endothelial pores - nutrients, waste products, and hormones can diffuse fairly readily across capillary walls.

Describe the origin and characteristics of platelets (thrombocytes) and state their major function in blood.

- they are fragments of the membranes of their precursor cells, megakaryocytes - they reside in the bone marrow and shed platelets into the blood stream - platelets participate in hemostasis (the control of bleeding, which coagulation and clotting) - in response to a break in blood vessels, a clumping together of platelets begins to create a physical barrier across the opening in the endothelium.

State why plasma proteins and blood cells cannot easily cross the vascular endothelium.

- they are too large to squeeze through the pores.

State the primary functions of leukocytes.

- white blood cells - they are critical in immune and allergic responses of the body - they are involved with protecting the body against both infectious disease and foreign invaders

Contrast the relative numbers of leukocytes and erythrocytes in normal blood.

1 WBC for every 1000 rbcs

Explain why whole blood is red, but plasma is pale yellow, and interstitial fluid is generally clear (nearly colorless).

Blood is red: oxygenated hemoglobin has a bright red appearance. Plasma is yellow: the presence of plasma proteins in the plasma gives it its pale yellow color. Interstitial fluid is colorless: doesn't contain anything to give it a certain color. main component is water.

Compare and contrast the composition of blood serum and blood plasma.

Blood serum: Blood plasma

Define what physiologists mean when they refer to the body's external environment. Define what physiologists mean when they refer to the body's internal environment. Identify the type of cell layer that generally separates the external from the internal environments.

External environment: the air, clothing, and water are in the body's external environment. They have not crossed the epithelium. Internal environment: on the other side of the epithelium. Type of cell layer that separates the two: epithelium

Define hematocrit and give typical values for men and women.

Hematocrit: fraction of cells in the blood Women: 36 - 46% Men: 41-53%

List the 4 fluid compartments whose volume you would have to sum up to calculate precisely the body's extracellular fluid volume.

Interstitial fluid + plasma vol + lymph vol + transcellular fluid vol

State the approximate fractions of the total body water that are found in the intracellular and extracellular spaces.

Intracellular : 2/3 Extracellular: 1/3

Using qualitative terms (more, less, about the same), compare and contrast the concentrations of Na+, K+, and Cl- in interstitial fluid and in intracellular fluid (using a typical skeletal muscle cell as an example).

Intracellular fluid: Main: K+ Main anion: intracellular (proteins) anions Low: Na+ Interstitial fluid (extracellular): Main cation: Na+ Main anion: Cl- Low: K+ ** H+ is low in both extracellular and intracellular fluid

List the major categories of substances found in normal interstitial fluid. (Remember to include the predominant interstitial substance in your list - HINT: It's a liquid!)

Its water.

State the main difference between the normal composition of plasma and interstitial fluid.

Plasma proteins.

Define invagination.

The act or process of being turned inside out or folded back on itself to form a cavity or pouch

Define cytosol

The composition of the intracellular fluid

Describe how a clinical laboratory would obtain a sample of blood plasma.

add an anticoagulant

State the relationship between interstitial fluid and the body's internal environment. Distinguish between intracellular fluid and the body's internal environment

interstitial fluid is part of the ECF, which is considered to external environment. Intraceullar fluid is on the inner part of the plasma membrane and is considered to be in the bodys internal environment.

State the approximate fractions of the extracellular fluid volume that are found in the interstitial and plasma spaces. Why are lymph and transcellular fluid volumes usually overlooked in making this approximation?

interstitial: 3/4 ECF, 1/4 plasma

Given the plasma volume and hematocrit, calculate blood volume.

plasma + hematocrit = total blood volume

Describe how a clinical laboratory would obtain a sample of blood serum.

serum is the plasma without fibrinogen - when centrifuged the fibrinogen settles to the bottom with the other cells.