The Blood

8% of body weight

Primary Functions

1. Transports

   • Dissolved gases (e.g. oxygen, carbon dioxide)

   • Waste products of metabolism (e.g. water, urea)

   • Hormones

   • Enzymes

   • Nutrients (glucose, amino acids, micro-nutrients, fatty acids, glycerol)

   • Plasma proteins (defense - such as blood-clotting and anti-bodies)

   • Blood cells

2. Maintains body temperature

3. Controls pH - must remain in the range 6.8 to 7.4, otherwise it begins to damage cells.

4. Removes toxins from the body - kidneys filter all of the blood in the body (approx. 8 pints), 36 times every 24 hours. Toxins removed from the blood by the kidneys leave the body in the urine.

5. Regulation of body fluid electrolytes - excess salt is removed from the body in urine, which may contain around 10g salt per day

6. Prevents from infection and loss of blood itself

Hemostasis - when tissue is cut and begins to bleed

• blood vessels constricts to slow flow

• platelets gather to patch the hole - when endothelial tissue is exposed, platelets are chemically triggered by collagen fibers to change consistency, becoming sticky and congealed (this prevents them form clotting all the time)

• fibrin threads (protein) join together and close vessel walls

• some people have disorders that prevent the formation of clots or the opposite, over production of clots

Hemopoesis/erythropoesis: blood cell production

• Erithrocytes, granulocytes, monocytes & lymphocytes

• occurs in liver & spleen of fetus

• bone marrow after birth

• undifferentiated cells undergo mitoic division, maturation into hematologic cells

• process continues throughout life and increasing when in need in response to infection, hemorrhage, hemolytic anemia, etc. Also chronic disease causes greater increase of hematopoesis.

• extramedullary hematoposis (production in tissues other than bone marrow) is a sign of disease including Computer pernicious anemia, sickle cell anemia, certain leukemias and more.

Structure & Function of the Blood

Whole Blood

• blood drawn directly from the body from which none of the components have been removed

• composed of formed elements, water, dissolved molecules

• connective tissue - living cells suspended in a non living matrix (plasma)

Formed Elements - 45%

composed of:

99% erythrocytes (RBCs)

Dense red layer in centrifuge blood tube

Structure, Life Cycle & Associated Parts: 

• last appx. 120 days

• approx. 4.5 - 5.8 million per micro-liter of healthy blood - varies between race and gender.

• biconcave shape (concaved on both sides)

• plasma membrane, but no nucleus - shed after birth as an erythroblast in bone marrow, causing its cells walls to slightly collapse, giving it its concave shape

• "glorified protein filled phospholipd bilayer sacks" - Hank

• large surface area - helpful for gas exchange

• flexible - squeeze through capillaries often smaller than themselves

• 97% hemoglobin (aside from water content) - binds to and releases oxygen

• RBC - contains around 250 million hemoglobin molecules - carrying around 1 billion oxygens at a time - 1 Fe - 1 O2

• 4 globin (globular polypeptide chain - protein) - 4 heme (red pigment) - 4 Fe (iorn) within heme

• balance of RBCs is maintained by Erythropoietin (EPO) - (hormone) produced by kidneys and liver, constantly circulating in the blood, preventing the over thickening and thinning of blood

• signalling molecule Hypoxia Inducinble Factor (monitors bloods level of oxygen)

• in the case of Hypoxia (low O2 at high altitudes) - specialized kidney cells need oxygen to break down HIF, so if O2 levels are low, HIF is not turned off, causing the production of more EPO, signaling the red bone marrow to produce more RBCs to carry more oxygen, degrading signal, slowing epo production - negative feedback!

• old eurithrocytes - carried to the spleen, liver and bone marrow (red blood cell graveyard) by macrophages and broken down into:

  • blood pigments bilinubin & bilviridin and iron are transported by the blood to the liver where the iron is re-cycled for use by new erythrocytes, and the blood pigments form bile salts into poop

  • globin proteins are broken down into amino acids and reused

  • spleen brakes down RBCs and stores or releases heme

Function: Gas Exchange - carry oxygen and distribute it through out your body, then pick up co2 to be exhaled

1% leukocytes (WBCs) * -

White layer in centrifuge blood tubes

Structure:

Granular: Neutrophils, Eosinophils, Basophils

Agranular: e.g. Monocytes, Lymphocytes

• can last few hours, few days, sometimes longer

• approx. 5,000 - 10,000 per micro-liter of blood

Function: Major part of the immune system

Thrombocytes (blood platelets) -

Structure:

• cell fragments

• disk-shaped fragments

• diameter 2-4 um

• last approx. 5-9 days

• approx. 150,000 - 400,000 platelets per micro-litre of blood

Function:

• to facilitate blood clotting & the breakdown of

• digest and destroy bacteria

• secrete chemicals the illicit an immune response

• secrete growth factor to maintain the lining of the vessels

Plasma - 55%

Structure:

• 90 - 92% water

• fluid in which the blood cells are suspended

• electrolytes - positively charged cations (sodium, calcium,potassium) & negatively charges anions (phosphate, sulfate, bicarbonate)

• blood plasma proteins - albumin, globulin, fibrinogen

• hormones

• gases

• waste products

Function:

• medium in which blood cells are transported around the body

• maintains optimum body temperature

• controls the pH of the blood and the body tissues,

• maintains an ideal balance of electrolytes in the blood and tissues

The Heart

• a pump - maintaining pressure and movement of blood through the body

• size of two fists clasped together - weights 250-350g

• sits centered & angled from top right to bottom left in mediastinum cavity in between the lungs

• nestled in double walled sack called Pericardium

  • Fibrous Pericardium - made of dense connective tissue, provides structural support and protection

  • Serous Pericardium - enclosed within the fibrous pericardium - divided into two layers – each layer is made up of a single sheet of epithelial cells - mesothelium

    • Parietal Layer - lines internal surface of FP

    • Serous Fluid - a cts as a lubricant and reduces friction from muscle movement

    • Visceral Layer - forms the outer layer of the heart

• Interior layers: epicardium, myocardium, endocardium

• divided into two chambers by interventricular septum - right (deoxygenated) and left (oxygenated) - both containing superior atria (low pressure - receiving) and inferior ventricles (high pressure - discharging)

• Valves to regulate flow & pressure:

  • The Tricuspid valve separates the right atrium from the right ventricle

  • The Pulmonic / Pulmonary valve separates the right ventricle from the pulmonary artery

  • The Mitral (aka Bicuspid) valve separates the left atrium from the left ventricle

  • The Aortic valve separates the left ventricle from the ascending aorta

• pacemaker cells - keep heartbeat in rhythm and ensure coordinated cardiac cell function - leaky Na/K channels - originating in sinoatrial node - producing a cardiac muscle cascade

• Intrinsic Cardiac Conduction System (heart beats) - transmits electricity along a precisely timed pathway which ends with valve contraction

• divided into two chambers by interventricular septum - right (deoxygenated) and left (oxygenated) - both containing superior atria (low pressure - receiving) and inferior ventricles (high pressure - discharging)

Pulmonary and Systemic Circuits

Pulmonary Circuit (Pulmonary circulation loop)

• the path of circulation between the heart and the lungs

• carries oxygen-depleted (deoxygenated) blood away from the right ventricle to the lungs via the pulmonary artery and returns oxygen-rich (oxygenated) blood from the lungs back to left atrium via pulmonary vein

The oxygenation of blood

• a function of the erythrocytes (RBCs) - takes place in the lungs

• while in the lungs:

1. CO2 diffuses out of the blood into the lungs

2. Oxygen (breathed into the lungs) combines with hemoglobin as it passes through the lung capillaries becoming Oxyhemaglobin

3. O2 binds to Fe within the hemoglobin

Systemic Circuit (systemic loop)

• path of circulation between the heart and the rest of the body (-lungs)

• oxygen-rich blood in the left ventricle leaves the heart via the aorta - blood is circulated to the rest of the body by various major and minor arteries

• Oxygen-poor blood returns back to the hearth via systemic veins into the vena cavae

Two circuits are necessary to allow for two different processes to be operating at all times - circulating through body by pressure gradients & providing the functions each one is dependent on simultaneously - distribution of O2 and processing of Co2 

Blood Vessels - Components & Functions

Arteries:

Structure:

• walls are composed of smooth muscle which contracts and relaxes under automation from the SNS

Functions:

• transport blood away from the heart

• Carry oxygenated blood (-pulmonary artery)

• narrow lumen

• muscular/elastic - to absorb large pressure fluctuations

• transports blood under pressure

• no valves (- semi-lunar valves of the pulmonary artery and the aorta)

Aorta:

• main artery which carries blood away from the heart

• blood is pumped from the left ventricle of the heart (via the aortic valve) into the aorta

• diameter of a garden hose

Major muscular arteries:

composed mostly of smooth muscle to respond to the SNS for vaso- constriction & dilation

• Coronary Arteries: blood vessels that branch off from the ascending aorta - supply blood to the heart tissues

• Brachiocephalic Artery: supplies blood to the head, neck and arms

• Celiac Artery: supplies blood to the abdominal area

• Splenic Artery: supplies blood to the spleen, stomach, and pancreas

• Renal Arteries: supply blood to the kidneys

• Common Iliac Artery: supplies blood to the legs and feet

Arterioles:

Structure:

• tiny branches of arteries that lead to the capillaries

• controlled by the sympathetic nervous system - automated constriction and dilation of blood flow

The functions of arterioles include:

• transport blood from arteries to capillaries

• main regulators of blood flow and pressure

Capillaries:

Structure:

• tiny & very narrow blood vessels - single layer epithelium

• networks of capillaries exists in most organs and tissues of the body

• supplied with blood from arterioles and drain into venules

• wall is one cell thick which allows for exchange of material to and from surrounding tissue

• form capillary beds

Functions:

• supply tissues and transport nutrients from the blood

• remove waste from the surrounding cells

• exchange of gas, nutrients & waste between the blood and the surrounding tissues

• regulate body temperature

  • squeeze to prevent blood flow to exposed and cold areas, therefore keeping blood warm

  • expand in heat allowing freer blood flow to disperse heat - often causing redness

* In organs such as the spleen, liver, and bone marrow which do not have capillaries, exchange occurs in vessels called sinusoids

Veins:

Structure: 

• walls consist of three tissue later that thinner and less flexible than arteries

• valves throughout the main veins of the body

Function:

• transport blood towards the heart

• carry deoxygenated blood (-pulmonary vein)

• wide lumen

• transports blood under lower pressure

• valves aid in the return of blood to the heart preventing flow in the reverse direction - esp rev gravity

• back-flow of blood = varicose veins/hemorrhoids

Venules:

Structure:

• very tiny vessels that drain blood from the capillaries into the veins

• many venules unite to eventually form a vein

Function:

• drain blood from capillaries into veins to return to the heart

Hepatic Portal System

• the hepatic artery supplies the liver with oxygenated blood (25% of blood supply)

• de-oxygenated blood from the GI travels into a vein called the portal vein which carries nutrients (absorbed from digestion) to the liver (75% of blood supply)

• blood is absorbed through the hepatic sinusoids

• once the liver has used the nutrients from the de-oxygenated blood it processes it and sends it our via the hepatic vein

Portal Vein: 

• system lacks valves - blood can flow in any direction depending on pressure gradient

• serves as a drain from the GI (splenic vein, inferior & superior mesenteric vein)

• portal hypertension - back up can cause blood to enter vena cavae (cavae drainage) causing hemorrhoids/splenomegalie/caput medusa/more serious conditions

• micells transport fat molecules (two fatty acids & monoglyceride) through membranes/erythrocytes of small intestine into lymph lacteals (lymph capillaries) and then into blood to be carried to the liver or stored in adipose or muscle tissue

Proper function of this system is crucial. It delivers important nutrients to the liver to supply the body for proper function (minerals, glucose, etc). It is also responsible for carrying toxins that are ingested to the liver for proper processing into bile or detoxed via hepatocytes, preventing unwanted materials from entering the bloodstream.

Blood Pressure

Blood Pressure is how the body moves blood throughout the body

Hypertension (High BP) 

• can cause serious damage to both the heart (which creates the extra pressure) and the vessels (which have to withstand the extra pressure)

• causes loss of elasticity in veins

• exhausts hear from over working

• many things can cause hypertension

• resistance influencing vessel diameter causes changes in pressure

  • change can be temporary vaso- contriction & dilation

  • excess LDL can build up plaque, causing friction and narrowing of the vessels

• Heart develops more muscle around left ventricle to help move blood - causing more need for oxygen - resulting in starvation and death of heart muscle cells - Heart Failure/Heart Attack

• Arteriosclerosis - plaque build up results in stiffening of vessel leading to poor circulation

• Aneurysm - weakening and bulging of the vessel

The Body's Attempt to Maintain Homeostasis

Neurons

• extremely fast response

• brain attempts to alter the distribution of blood throughout the body or change the diameter of certain blood vessels

• bororecepters - signal stretch/pressure to brain via action potential - higher the BP the higher the AP & greater response to change it

• responded to be the autonomic nervous system

• brain will dilate, reduce heart rate, ect. in response to change in signal

• constant pressure makes bororeceptors not effective long term because brain will accept high BP as the new normal

• low brood pressure indicates much lower amount of stretch

If there is a change in the bororecepter response, the nervous system steps in...

Pressure = Flow (stroke volume x heart rate) x Resistance

Stroke volume - the amount of blood ejected by the (most commonly referred to) left ventricle in one contraction

Hormones

• fight or flight - adrenal medula floods blood with EP & NP - raising heart rate and blood volume increasing cardiac output

• constricting places that are of no use to increase resistance and pressure for better performance in fight mode

• change vessel resistance and cardiac output

The Kidneys

• long term control

• alter blood volume

• renin & angiotensin

  • help regulate levels of sodium and fluid in the body

  • help expand and contract blood vessels

• when blood pressure is high, the kidneys will make room for the increased blood volume through urination

• excess sodium > body retains water > higher blood volume > high blood pressure

* Sodium is the primary determinant of blood volume. Salt restriction (or diuretic treatment) reduces blood volume-this is one way to lower pressure. In the last decade another mechanism by which sodium increases blood pressure has been described. A family of compounds called glycosides is produced by the brain and the adrenal gland in response to increased sodium. These compounds stimulate the smooth muscle cells in the walls of blood vessels to contract and thereby increase vascular resistance. So salt gets your blood pressure up both by increasing blood volume (and cardiac output) and increasing vascular resistance. - Dr. Charles Whitcomb

The Lymphatic, Cardiovascular, Immune System Connection

The lymphatic system plays a vital role in supporting the cardiovascular and immune systems. Because the heart has an extremely high pressure to circulate blood throughout the body, fluid (plasma) and proteins is forced out through capillaries interstitial fluid which resides outside of capillaries. The solutes that are pushed out from the bloodstream provide nutrients to the cells along the capillaries including gasses, hormones, vitamins, etc. If the fluid accumulates for too long will cause a build up (edema). The lymphatic system addresses the fluid that has been pushed out into the interstitial space. The lymph vessels (residing in the interstitial fluid) take in the fluid into the interstitial lymphatic compartment and bring it back into circulation right before the heart. Otherwise, the osmotic pressure forces some of the solutes back into the bloodstream, although more goes out than back in.

The lymph plays an important role in immune response to the tissues of the body. When bacteria enters the tissues, it is swept up (along with the first responder macrophages) into the lymph vessels and taken to the node where the immune system has t-cells and b-cells ready to react and respond appropriately to the bacteria, sending the immune response to the local infection if need be.

The Lymphatic System

Lymph Fluid:

• begins as blood plasma that is forced out of capillaries and absorbed by the lymph, inspected by the immune system, and sent back into circulation near the heart

• 94% water and 6% solids consisting of proteins, carbohydrates, fats, minerals, WBCs, enzymes, salts for re-regulation into the bloodstream and use by the tissues

• also absorbs tissue debris, waste, bacteria, cancer cells, dead cells for processing

• recover 3L of blood fluid/day

• plasma proteins

• does not contain any RBCs (too large)

• Picked up by lymphatic capillaries in the interstitial space

  • dispersed among the blood capillaries

  • made of loosely overlaid epithelial cells

  • have flap-like valves that ensure no fluid enters back into interstitial space

  • once fluid enters, it becomes lymph

Travels to Lymph Node > Lymph Trunk > right or left Lymph Ducts that feed back into the lowest pressure area (subclavian vein) of the circulatory system > returning proteins and excess interstitial fluids back into the bloodstream

* Fats (dietary lipids and lipid-soluble vitamins) unlike other nutrients, are not absorbed by the bloodstream, but rather by the lymph into special capillaries called lacteals located within the small intestine, forming a milky substance celled chyle. The chyle is processed through the liver and redistributed back into to the bloodstream along with the other lymph at the subclavian veins - linked to overburden of toxins from unhealthy processed and animal fats

In the small intestine, lymphatic capillaries called lacteals are critical for the transport of dietary lipids and lipid-soluble vitamins to the bloodstream. In the small intestine, dietary triglycerides combine with other lipids and proteins, and enter the lacteals to form a milky fluid called chyle. The chyle then travels through the lymphatic system, eventually entering the liver and then the bloodstream.

Lymph Vessels:

• low pressure system

• moved along by a series of one way valves, smooth muscle, muscle (exercise!) and gravity

Components:

• Lymph Nodes

  • monitor and cleanse lymph as it filters through - working with the immune system to identify and tag intruders (antigens)

  • receive dendritic cells enter with processed antigens and microorganisms form other tissues

  • inspected by lymphocytes and monocytes

  • found and mature in the loose reticular connective tissue which makes up a large part of the nodes and other lymph tissues

  • inflamed nodes signify disease or infection

• Mucosa-Associated Lymphoid Tissues (MALT) - found in mucus membrane tissues of the digestive reproductive systems

  • Tonsils - inspect everyhting that enters the GI & Lungs

  • Pyers patches - monitor activity along the small intestine

  • Appendix - final stop to breach bacteria before it enters the intestinal wall during absorption

• Lymphatic Pump - A manual mechanism for moving lymph fluid through the vessels by increasing pressure and directing flow

Plasma Proteins like albumin and globulins are produced in the liver. Antibodies (immunoglobulins) are produced in lymphatic nodes & tissues.

Lymphoid Organs:

Comprised of primary and secondary organs, often aggregations of lymphoid tissues. They operate as sites of residence, proliferation, differentiation, function of lymphocytes and mononuclear phagocytes.

Primary:

Thymus -

Bone Marrow

• residence of hematopoeitic stem cells - formation of blood cells

• red/active marrow, also known as myeloid tissue, only found in certain bones including pelvis, vertebrae, cranium, mandible, sternum, ribs, and proximal portions of the humerus and femur. /

• yellow/inactive: composed of fat

• newly formed blood cells travel into circulation from through venous sinus walls

• niches: cellular microenviornment that includes osteoclasts, osteoblasts, sinusoidial endothelial cells, fibroblasts, megakaryocytes, macrophages, and nerve cells.

• production of cells controlled by a

Secondary:

Spleen

• site of fetal hematopoisis, mononuclear phagocytes filter & clean blood, lymphocytes mount an immune response to blood born microorganisms, blood reservoir - venous sinuses.

• contains masses of lymphatic tissue called splenic pulp: composed of macrophages and lymphocytes

• receives blood form the splenic artery and carries blood back out via the splenic vein (back to the heart) and portal vein (to the liver)

• catabolizes erythrocytes and remaining heme is stored in cytoplasm of macrophages or released back into the blood

Lymph Nodes

Tonsils

Peyers patches

The Immune System

The immune system serves as housekeeping for the body, rather that killing everything at first site, it methodically organizes and deliberately acts to further strengthen the body from threats. We have evolved with bacteria and must recognize the key role their co-existence plays in our health. When the body has overcome a pathogen, it becomes a part of us, allowing for quicker identification and the method in which to deal with it and similar invaders. "We get sick when we invite germs to come and make order in the polluted body" - Sara Hamo

As Rudolph Virchow says "If I could live my life over again, I would devote it to proving that germs seek their natural habitat –diseased tissue– rather than being the cause of the disease tissue, in the way that mosquito seat is stagnant water, but do not cost the pool to become stagnant"

This is an important way to address disease and chronic illness in the body. Supporting the body as a whole in order to heal and learn from its experience.

C'est le terrain!

Innate and Adaptive Immune Defenses

The immune system can be divided into two cooperative systems:

• innate immune response (simple) - rapid and non-specific (not always effective)

• adaptive immune response (acquired) - slow during initial response to a pathogen, but highly specific and effective against pathogens

Innate Immunity:

• external barricades - skin & mucous membranes

• internal defenders & mechinsms

First on site

Basophils:

• contain anticoagulant heparin, which prevents blood from clotting too quickly

• contains histamine, which promotes blood flow to tissues

• an increased in the presence of basophils in the blood may indicate an inflammatory condition somewhere in the body

Neutrophils - first to bacterial invasion of the body, carry out the process of phagocytosis, and release enzymes that destroy bacteria

Monocytes - arrive in much larger numbers entering infected tissue as macrophages and clear up cellular debris after an infection

Eosinophils:

• disease fighting white blood cells

• an increased presence of eosinophils in the blood may indicate parasitic infection somewhere in the body

Phagocytes: engulf and digest bacteria, protozoa, cells, cell debris, and other small particles. Phagocytes include many leucocytes (white blood cells) and macrophages - which play a major role in the body's defence system.

* Phagocytosis is the engulfment and digestion of bacteria and other anigens by phagocytes.

Natural killers (NK) - cytotoxic T cell that patrol blood & lymph destroying abnormal cells (will destroy self w/o MHC1) by apoptosis via perforins & granzymes or fas ligand

* fas ligand - molecule expressed on cytotoxic T cells and NK cells that binds to the fas molecule on a target cell and induces it do undergo apoptosis

* granzyme - apoptosis-inducing substance contained in granules of NK cells and cytotoxic T cells

* Innate immune cells have a pattern recognition receptor (PRR) - membrane-bound receptor that recognizes characteristic features of a pathogen and molecules released by stressed or damaged cells - but is very limited in its ability compared to adaptive immune cells specialization, therefor a limited number of receptors that are active against as wide a variety of pathogens as possible

*SOME* Inflammatory mediators - cells that plays a role in inflammation

• basophil - white blood cell that contains inflammatory mediators

• prostaglandin - hormone-like molecules that participate in diverse body functions including inflammation; their production is blocked by NSAIDs

• histamine - released especially during an allergic response that causes smooth muscle contraction, inflammation, mucus secretion, and other allergy symptoms

• leukotrienes - mediate the allergic response that causes lung constriction and muscle contraction in asthma

• Mast cell - found in the skin and the lining of body cells that contains cytoplasmic granules with vasoactive mediators such as histamine

Signaling Cells

• cytokines are secreted into the intercellular space inducing the receiving cell to change its physiology and duplicate

• chemokines causes white blood cells to move throughout the body via the process of chemotaxis

Early Induced Proteins - made as needed

• Interferon - virus infected cells secrete interferon which travels to adjacent cells, inducing them to make antiviral proteins , warning and protecting cells

• mannose-binding protein and c-reactive protein - made in the liver - bind specifically to polysaccharide components of the bacterial cell wall - this attracts phagocytes who have receptors for these proteins, making them more likely to engulf the cell - this process is called opsonization - the specific tagging of a pathogen for phagocytosis by the binding of an antibody or an antimicrobial protein

Inflammatory response - redness, heat, swelling, pain

• mast cells in connective tissue - release histamine, leukotrienes & prostaglandins causing inflam. response

  • vasodialation - increasing temperature and blood supply

  • increased blood vessel permeability - causing nearby capillaries to release protein rich fluid - swelling

• phagocytes and lymphocytes - clean & kill

• macrophages take the place of now dead neutrophils

• transport of antigen (markers) to lymph nodes by dendritic cells for the development of the adaptive immune response

• sometimes when the immune defense is locally overpowered they will secrete pyrogen chemicals with signal the thalamus to create a fever - also warning the liver and spleen to hold on to iron and zinc so they wont contribute to bacterial growth

Adaptive immunity:

• expressly introduced to a specific pathogen and acquired response

• developed over time

• specific response

• remembers pathogens

• systemic - fights throughout whole body at once

Two Defenses

how is this knoledge useful in herbal medicine? where do I even begin?