Capillary Action and Blood Components Biology 20 Unit D: Body Systems Circulation 1
Remember. Capillaries are so small that blood cells can only pass through single file Important because they are the only vessels THIN enough for diffusion of nutrients, wastes, and gases 2
Network Capillaries work in NETWORKS or BEDS throughout body Bed is formed between a branch of an artery and a branch of a vein 3
Precapillary Sphincters Blood flow not always constant in capillaries If cells beside certain capillaries don t need to be serviced by the blood, blood flow can be stopped from going to that capillary 4
Precapillary Sphincters Con t Done by PRECAPILLARY SPHINCTERS that contract and close the opening to that specific capillary Blood then passes right from artery to vein through main capillary 5
When do the these sphincters constrict blood flow? After eating Capillaries feeding certain muscles are closed All the capillaries of the digestive system are open Ie) capillaries in villi of small intestine While exercising Capillaries feeding muscles are open, and the some capillaries feeding the digestive system would be closed 6
Interstitial Fluid Liquid that surrounds body cells and capillaries Material exchanged between body cells and capillaries must travel through this fluid 7
Sections of Capillaries Arterial end Blood is bright red because hemoglobin in red blood cells contain lots of oxygen Mid-section Where diffusion of materials takes place Direction of diffusion decided by a material s concentration gradient Venous end Blood is blue looking because there is minimal oxygen present and lots of carbon dioxide 8
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Blood Flow Speed in Capillaries Slower than any other part of system Allows time for diffusion of materials Pressure is lower than arteries, but still more than veins Ensures blood keeps moving 10
Blood Components 2 main elements: fluid and solid portions PLASMA = fluid portion FORMED PORTION = solid portion 11
Plasma Consists of water, dissolved gas, proteins, sugars, vitamins, minerals, hormones, and waste products 55% of blood volume 12
Formed Portion Consists of: red blood cells white blood cells platelets All produced in bone marrow 45% of blood volume 13
Red Blood Cells (RBC) Aka Erythrocytes ~44% of the total volume of blood Specialized for O 2 transport The O 2 carrying capacity of blood is based on # of RBC present and the amount of HEMOGLOBIN on each Mature RBC has no nucleus 14
Hemoglobin Each RBC contains ~280 million Iron-containing Allows large sums of O 2 to be transported in blood Special properties that let it chemically bind with O 2 Then releases O 2 by diffusion to cells that need it 15
Hemoglobin Con t After CO 2 (waste) is diffused into the blood, it enters the RBC where a small amount is chemically binded to hemoglobin 16
Anemia Disorder that occurs when there are: too few RBC OR too little hemoglobin inside the RBC in blood These deficiencies reduce the amount of O 2 that is flowing through body May be caused by not eating enough iron (mineral) 17
White Blood Cells (WBC) AKA Leucocytes Apart of body s response to infection ~1% of total blood volume (X2) when fighting infection Colorless and have a nuclei Divided into 3 groups: Granulocytes Monocytes Lymphocytes 18
1. Granulocytes Consist of: Neutrophils Basophils Eosinophils Typically found circulating in blood with granulocytes engulfing foreign bodies 19
2. Monocytes Can leave bloodstream and become further specialized into MACROPHAGES (destroy bacteria engulf it) Typically found circulating in blood with granulocytes engulfing foreign bodies 20
3. Lymphocytes Some produce ANTIBODIES Proteins that incapacitate pathogens and allow them to be easily detected and destroyed 21
Platelets Pieces of cells that form when larger cells in the bone marrow break apart No nucleus Breaks down quickly in blood Play key role in blood clotting 22
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Stages of Clotting 1. Blood vessel broken due to injury 2. Substances released at site to attract platelets 3. Platelets at site rupture, releasing chemicals that combine with blood components to produce enzyme called THROMBOPLASTIN 24
Clotting Con t 4. As long as there is Ca+ present, THROMBOPLASTIN will react with PROTHROMBIN to produce THROMBIN Prothrombin is a plasma protein produced in liver 5. THROMBIN (enzyme) reacts with FIBRINOGEN (protein) to produce FIBRIN 6. FIBRIN forms mesh strands around injured area, thus preventing more blood loss Forms clot 25
What if your blood doesn t clot? 26
Plasma Fluid portion of blood Carries all blood cells Is a mixture: 92% water 7% Blood Proteins 0.1% Organic Substances (ie.urea) 0.9% Inorganic Ions (sodium, chlorine, magnesium, potassium, calcium, biocarbonates, phosphates, etc) 27
Plasma Con t CO 2 is dissolved in the water portion of plasma when transported in the blood Forms carbonic acid in cytoplasm of RBC Then diffuses out of RBC into the plasma as bicarbonate ions and is carried from tissues to the lungs for gas exchange 28