The Bodys Natural Protective Mechanisms Agains Heat Loss Are
| BIO 301 Human Physiology |  |
Functions of Blood:
- i - Transportation:
- oxygen & carbon dioxide
- nutrients
- waste product products (metabolic wastes, excessive water, & ions)
iii - Protection - clotting mechanism protects against blood loss & leucocytes provide immunity against many disease-causing agents
Components of blood
Components of Blood - average adult has about five liters (about v qts):
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Scarlet blood cell, platelet, and white blood cell
Red Blood Cells (or erythrocytes):
- ane - biconcave discs
two - lack a nucleus & cannot reproduce (average lifespan = about 120 days)
3 - send hemoglobin (each RBC has about 280 meg hemoglobin molecules)
4 - Typical concentration is 4-six million per cubic mm (or hematocrit [packed cell volume] of about 42% for females & 45% for males)
5 - contain carbonic anhydrase (critical for send of carbon dioxide)
Determining the hematocrit
Erythropoiesis = formation of erythrocytes
- the body must produce about 2.v million new RBCs every second
- in adults, erythropoiesis occurs mainly in the marrow of the sternum, ribs, vertebral processes, and skull basic
- begins with a cell called a hemocytoblast or stem cell (below)
- rate is regulated by oxygen levels:
- hypoxia (lower than normal oxygen levels) is detected by cells in the kidneys
- kidney cells release the hormone erythropoietin into the blood
- erythropoietin stimulates erythropoiesis by the bone marrow
training.seer.cancer.gov
Three main classifications of blood cells derive from haematopoietic stem cells (HSCs) (Katsura 2002).
-
Myeloid cells. This includes macrophages (monocytes) and granular white claret cells (or granulocytes; neutrophils, basophils and eosinophils). Macrophages have a role in adaptive immunity, cooperating with T and B cells through antigen presentation and the production of cytokines.
- Erythroid-megakaryocytes. Erythrocytes (red claret cells) carry oxygen through blood vessels, whereas platelets derived from megakaryocytes piece of work to prevent claret loss.
- Lymphoid cells. This includes T-cells and B-cells. Natural killer (NK) cells are thought to be the prototype of T cells. Thymic, also as pre-thymic, T-jail cell progenitors are able to generate dendritic cells. B cells secrete antibodies.
Hemoglobin
- composed of globin (fabricated up of 4 highly folded polypeptide chains) + four heme groups (with iron)
- each molecule tin can behave 4 molecules of oxygen
- called oxyhemoglobin when carrying oxygen & chosen reduced hemoglobin when not conveying oxygen
- tin also combine with carbon dioxide & helps ship carbon dioxide from the tissues to the lungs
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Hemoglobin and oxygen ship
White blood cells (or leucocytes or leukocytes):
- have nuclei & do not comprise hemoglobin
- typical concentration is 5,000 - nine,000 per cubic millimeter
- types of WBCs:
- granular white blood cells include:
- neutrophils (50 - 70% of WBCs)
- eosinophils (1 - 4%)
- basophils (less than 1%)
- agranular (or non-granular) white blood cells include:
- lymphocytes (25 - 40%)
- monocytes (ii - eight%)
Granular white blood cells contains numerous granules in the cytoplasm, & their nuclei are lobed. Agranular white claret cells accept few or no granules in the cytoplasm & accept a large spherical nucleus. Granular white blood cells are produced in the bone marrow, while agranular white blood cells are produced in lymph tissue, e.g., Lymph nodes (specialized dilations of lymphatic tissue which are supported inside by a meshwork of connective tissue called reticulin fibers and are populated by dense aggregates of lymphocytes and macrophages).
How white blood cells are formed
The chief functions of the diverse white blood cells are:
- Neutrophils - phagocytosis (bacteria & cellular droppings); very important in inflammation
Neutrophils
- Eosinophils - assistance initiate and sustain inflammation and tin activate T-cells (directly by serving equally antigen-presenting cells and indirectly by secreting a variety of cytokines). Eosinophils tin can also kill bacteria by quickly releasing mitochondrial DNA and proteins (described beneath).
Eosinophils respond to diverse stimuli, including tissue injury, infections, allografts, allergens, and tumors. Eosinophils can also release a diversity of cytokines, chemokines, lipid mediators, and neuromodulators. Eosinophils directly communicate with T cells and mast cells. Eosinophils actuate T cells past serving as antigen-presenting cells.
- Basophils - forth with mast cells, play a office in inflammation and allergic responses
Release of histamine (that contributes to the 'symptoms' of allergies) past mast cells requires the production of antibodies (IgE) by B-cells and
that process is regulated, in role, by cytokines produced by basophils (Bischoff 2007).
- Monocytes - phagocytosis (typically as macrophages in tissues of the liver, spleen, lungs, & lymph nodes) & also of import antigen-presenting cells
Once distributed through the claret stream, monocytes enter other tissues of the body such equally the liver (Kupffer cells),
lungs (alveolar macrophages), skin (Langerhans cells), and central nervous system (microglia) (Gordon 2003).
- Lymphocytes - allowed response (including product of antibodies)
Lymph system
Eosinophils (in greenish with red nucleus) catapult their mitochondrial Deoxyribonucleic acid out of the cell, forming tangled traps (red) that ensnare strange bacteria.
(Photograph credit: Hans-Uwe Simon, Institute of Pharmacology, University of Bern, Switzerland)
Catapult-like release of mitochondrial Deoxyribonucleic acid by eosinophils -- Although eosinophils are considered useful in defense mechanisms against parasites, their exact function in innate immunity remains unclear. Yousefi et al. (2008) found that eosinophils in the gastrointestinal tract release mitochondrial DNA in a rapid, catapult-similar manner—in less than one second. The mitochondrial Deoxyribonucleic acid and proteins released by the eosinophils demark to and kill bacteria. This is a previously undescribed machinery of eosinophil-mediated innate immune responses that might be crucial for maintaining the intestinal bulwark function after inflammation-associated epithelial prison cell harm, preventing the host from uncontrolled invasion of bacteria.
Some of import characteristics of White Claret Cells (particularly neutrophils):
- 1 - phagocytic
ii - capable of diapedesis (as well called extravasation)
3 - capable of ameboid move
four - showroom chemotaxis (attracted to sure chemicals, such equally those released past damaged cells)
Phagocytosis
Lymph arrangement
Chemotaxis & ameboid motion
Platelets (or thrombocytes)
1 - formed in the bone marrow from cells called megakaryocytes
Megakaryocytes. (A) & (B) immature cells. (C) mature prison cell producing platelets.
(Source: Battinelli et al. 2001).
two - accept no nucleus, but can secrete a diversity of substances & can also contract (because they comprise actin & myosin)
3 - normal concentration in the blood is about 250,000 per cubic millimeter
iv - remain functional for about vii - 10 days (afterward which they are removed from the claret by macrophages in the spleen & liver)
5- play an important role in hemostasis (preventing blood loss)
Platelet adhesion and aggregation
Plasma:
i - Water - serves as transport medium; carries heat
two - Proteins
- Albumins
- sixty-80% of plasma proteins
- most of import in maintenance of osmotic balance
- produced by liver
- Globulins
- alpha & beta
- some are important for send of materials through the claret (e.g., thyroid hormone & fe)
- some are clotting factors
- produced by liver
- gamma globulins are immunoglobulins (antibodies) produced past lymphocytes
- Fibrinogen
- important in clotting
- produced by liver
Twenty-2 proteins constitute 
3 - Inorganic constituents (one% of plasma) - e.g., sodium, chloride, potassium, & calcium
iv - Nutrients - glucose, amino acids, lipids & vitamins
5 - Waste products - east.g., nitrogenous wastes like urea
half-dozen - Dissolved gases - oxygen & carbon dioxide
seven - Hormones
Hemostasis - prevention of blood loss from broken vessel (check this Hemostasis animation and this i and this one):
Claret coagulation
ii - Formation of a platelet plug - platelets aggregate at the point where a vessel ruptures. This occurs because platelets are exposed to collagen (a protein establish in the connective tissure located only outside the blood vessel). Upon exposure to collagen, platelets release ADP (adenosine diphosphate) & thromboxane. These substances cause the surfaces of nearby platelets to become sticky and, every bit 'sticky' platelets accumulate, a 'plug' forms.
iii - Blood coagulation (clotting):
Used with permission of Michael W. King, Ph.D / IU School of Medicine
The result of all of this is a jell - formed primarily of fibrin threads (or polymers), only besides including blood cells & platelets.
Blood clots in the right places prevent the loss of blood from ruptured vessels, but in the wrong identify can crusade problems such as a stroke (run across beneath nether inappropriate clotting).
Jell retraction:
- "tightening" of clot
- contraction of platelets trapped within clot shrinks fibrin meshwork, pulling edges of damaged vessel closer together
Over time (with the corporeality of time depending on the amount of impairment), the clot is dissolved and replaced with normal tissue.
Fibrinolysis:
- dissolution of clot
- mechanism = plasminogen (a plasma protein) is activated by many factors & becomes PLASMIN. Plasmin so breaks downwards fibrin meshwork & phagocytic WBCs remove products of clot dissolution
- thrombus - jell formed in an intact vessel, possibly due to:
- roughened vessel walls (atherosclerosis; see normal & occluded coronary arteries beneath)
- boring-moving blood (east.g., in varicose veins) = small-scale quantities of fibrin form & accumulate
- cheque this animation about deep vein thrombosis
- embolus - 'moving' clot
Source: http://www.ors.od.nih.gov/medart/portfolio/Donny/embolus.html
Thrombus and embolus
Excessive haemorrhage:
- Hemophilia
- genetic 'defect'
- inability to produce sure clotting factor(s)
- Thrombocytopenia
- abnormally low platelet count
- most persons take idiopathic thrombocytopenia (= unknown cause) while in others information technology'due south an autoimmune disease
Thrombocytopenia is a condition where platelet counts are lower than normal, potentially leading to mild to serious bleeding. This bleeding can happen within the body (internal bleeding) or on the skin. A normal platelet count is 150,000 to 450,000 platelets per microliter of blood. A count of less than 150,000 platelets per microliter is lower than normal, but the take a chance for serious bleeding doesn't occur until the count becomes very low—less than 10,000 or xx,000 platelets per microliter. Milder bleeding sometimes occurs when the count is less than 50,000 platelets per microliter. Several factors can cause a low platelet count, such as:
- The bone marrow doesn't make plenty platelets.
- The bone marrow makes plenty platelets, but the trunk destroys them (autoimmunity) or uses them up.
- The spleen holds onto also many platelets. The spleen is an organ that normally stores about one-third of the trunk'southward platelets. It also helps your body fight infection and remove unwanted cell fabric.
- A combination of the above factors.
How long thrombocytopenia lasts depends on its crusade. It can range from days to years. The treatment for this condition also depends on its cause and severity. Mild thrombocytopenia almost often doesn't need treatment. If the condition is causing serious bleeding, or if you're at run a risk for serious bleeding, you may need medicines or blood or platelet transfusions. Rarely, the spleen may need to be removed. Thrombocytopenia can be fatal, especially if the bleeding is severe or occurs in the brain. However, the overall outlook is proficient, specially if the crusade of the low platelet count is found and treated (Source: NHLBI).
Related links:
Lifeblood
Astute Inflammation
Full general Immunology
Introduction to Immunology
Cell Mediated and Humoral Immunity
Understanding the Immune System
Humoral Immunity
Blood Types Tutorial
Literature Cited
Yousefi, S., J. A Gold, N. Andina, J. J. Lee, A. Chiliad. Kelly, Due east. Kozlowski, I. Schmid, A. Straumann, J. Reichenbach, G. J. Gleich, and H.-U. Simon. 2008. Catapult-like release of mitochondrial DNA past eosinophils contributes to antibacterial defense. Nature Medicine, published online (ten August 2008).
Dorsum to 301 syllabus Lecture Notes one - Cell Structure & Metabolism
Lecture Notes 2 - Neurons & the Nervous Organization I
Lecture Notes 2b - Neurons & the Nervous System Two
Lecture Notes 3 - Muscle
Lecture Notes 4b - Blood and Trunk Defenses Two
Lecture Notes 5 - Cardiovascular System
Lecture Notes 6 - Respiratory System
Lymph system graphic used with permission of John Kimball
Source: http://people.eku.edu/ritchisong/301notes4.htm
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