Circulatory System – Blood (Part 1 of 4)

The Circulatory System is made up of 4 parts:
1. Blood
2. Blood Vessels
3. Heart
4. Lymphatic System

Blood is the only liquid connective tissue in the body.

Human adults have 4.7 liters of blood in their bodies.

Blood has roles in transport, regulation and protection.
– It transports oxygen, carbon dioxide, nutrients, hormones, heat and waste.
– It is involved in the regulation of body temperature, PH and the water content of cells.
– The body is protected from blood loss through clotting and against disease by PHAGOCYTIC WHITE BLOOD CELLS and ANTIBODIES.

– Plasma makes up 55% of the blood.
– It is a clear; straw-colored liquid, which is mostly water.
– It is the bloods SOLVENT (able to dissolve substances).
– It transports nutrients, waste products of metabolism, respiratory gases and hormones.
– There are 3 main PLASMA PROTEINS:
– Is the smallest and most numerous protein.
– It helps recover water that has been lost.
– It transports some of the steroid hormones.
2. IMMUNOGOBULIN (antibodies)
– Aids the immune system by attacking bacteria and viruses.
– Other globulins help in the transport of iron, lipids and fat-soluble vitamins.
– It plays an essential role in the clotting of blood, by providing the necessary protein network.
– Various ions act as solutes in plasma; they play key roles in osmotic balance, PH buffering and the regulation of membrane permeability.

Blood cells make up about 45% of the blood.

There are 3 main types of blood cells:
– They transport oxygen to all cells.
– The oxygen-carrying protein HEMOGLOBIN is the pigment that gives blood its red color.
– They are the simplest cells in the body; mature red blood cells lack a nucleus, ribosomes and mitochondria.
– They are also the most numerous cells in the body; 5 million/ml of blood.
– About 2.5 million are made every second in the red bond marrow.
– Mature cells are flattened and disc-shaped with a central depression.
– They are non-reproducing sacks of oxygen binding hemoglobin.
– The hormone, ERYTHROPOIETIN, triggers transformation of skin cells in the marrow to produce red blood cells.
– After circulating for 3 to 4 months in the blood, red blood cells are engulfed by liver and spleen SCAVENGER CELLS.

– They contain a nucleus.
– Most live only a few days, although some, particularly LYMPHOCYTES can live for several months or longer.
– During infections white blood cells may only live for a few hours.
– The shape of their nuclei and the staining properties of their granules distinguish white blood cells from each other.
– The number and type of white blood cells can indicate a person’s health. Most infections stimulate an increase in circulating white blood cells.
– There are 5 classes of white blood cells:
– Are active in PHAGOCYTOSIS (the engulfing of particles by phagocytes); ingesting bacteria and cellular debris.
– Certain chemicals released by bacteria and inflamed tissue attract the white blood cells to the site.
– After engulfing the bacteria, neutrophils lysozymes are released that destroy the bacteria.
– Strong oxidants are then released, like peroxide and proteins called DEFENSINS that have antibiotic activity.
– Monocytes arrive after the neutrophils and enlarge to become macrophages, which clean up cellular debris and bacteria after an infection.
– They enter tissue fluid from the capillaries and release enzymes to combat allergic reactions.
– Intensify the inflammatory response when they enter the tissue from the capillaries.
– They are the major combatants in the immune response.
– They are the B-CELLS, T-CELLS and the natural killer cells.
– These cells are active in fighting infections caused by viruses, bacteria and fungi.
– They are also responsible for transfusion reactions, allergies and the rejection of transplanted organs.

– They are the small cell-like fragments that come from special white blood cells, called MEGAKARYOCYTES.
– They have no nucleus and live for about 5 to 9 days.
– Aged and dead platelets are removed by macrophages in the liver and spleen.
– Platelets release chemicals in blood clotting.

Humans have highly individualized blood that is credited to proteins and other genetically determined factors located on the surface of red blood cells and the plasma bathing the red blood cells.

The main types of blood are A, B, AB, and O.

Transfusions of blood are possible only when the blood types of the donor and recipient are compatible.

If the blood types are not compatible, proteins in the plasma will recognize foreign antigens and respond by causing the cells to AGGLUTINATE (clump) which will block the small vessels.

Type AB is considered the UNIVERSAL RECIEPENT (this person can receive blood from any type in the ABO blood group).

Type O is considered the UNIVERSAL DONOR (this type of blood can be given to any blood type in the ABO blood group).



To stay alive the cells of an organism need proper nutrients, oxygen and it’s metabolic waste must be removed. This goal affects the organism’s interactions with its environment.

The component parts of any organism (whether it is one-celled or a human being) must work together to maintain a stable fluid environment that all of its cells require. There must be a relative consistency (a controlled sameness) of the organisms internal environment. This is the basic concept of Homeostasis.

Multicellular organisms must regulate their internal environment. Maintenance of a stable internal environment is critical to the well-being of an organism; regulatory mechanisms must be carefully controlled.

It is important that an organism keep its chemical processes occurring at the correct rate and time.

When living things are able to regulate these chemical processes precisely, they can maintain a stable internal environment.

HOMEOSTATIC CONTROL mechanisms help maintain, both physical and chemical aspects of an organisms internal environment within ranges that are favorable for cells to function.

1. SENSORY RECEPTORS: Cells that can detect stimulus (a change in the environment).
2. INTEGRATOR: The BRAIN processes the information about the stimulus and selects a response.
3. EFFECTORS: Carry out the response to the stimulus (MUSCLES&/or GLANDS)

FEEDBACK MECHANISMS are the controls that operate to keep chemical and physical aspects of the body within tolerable ranges.

A VARIABLE in the environment triggers the mechanism. A variable triggers change.

A POSITIVE FEEDBACK mechanism amplifies positive change.

in a NEGATIVE FEEDBACK mechanism, something alters the condition in the internal environment, and this triggers a response to reverse the altered condition.

Homeostasis is dependent upon positive or negative feedback mechanisms.


Photosynthesis is the reverse of Cellular Respiration.

The main end products of respiration are CO2 (carbon dioxide) and water, which are used as the starting material for Photosynthesis, and photosynthesis converts them into glucose and O2 (oxygen).

Photosynthesis is the ultimate source of all energy rich carbon compounds used by all organisms; it is responsible for the continual supply of atmospheric O2 (oxygen), without which all the aerobic organisms, that use oxygen would not exist.

Green plants, algae, some unicellular green flagellates and 2 bacteria groups are the only organisms that photosynthesize. Each year they release half of all the O2 (oxygen) in the atmosphere.

Plants use CO2 (carbon dioxide) when they produce O2 (oxygen). CO2 is converted to O2 during photosynthesis. At the same time, animals through their respiration process use this O2 from their metabolism and replace it with CO2, which is then used by plants to begin the cycle again.

Photosynthesis is a solar powered process. SUNLIGHT is a key component of the process.

Light is a form of ELECTROMAGNETIC ENERGY. When light meets matter, it can be reflected, transmitted or ABSORBED.

PIGMENT absorbs light. Plant pigment, CHLOROPHYLL (the main light-absorbing molecule of green plants), is a pigment that absorbs LIGHT ENERGY.

Chlorophyll is found in specialized structures called CHLOROPLAST; they give plants their green color. Each chloroplast contains all the chlorophyll and enzymes needed to complete the complex chemical reactions of photosynthesis.

Chlorophyll participates directly in LIGHT REACTIONS.

The site of photosynthesis is typically the leaf of green plants. Each cell has about 30 to 40 chloroplast.

The large amount of chlorophyll in the leaves of plants allows it to produce most of their own FREE ENERGY, by using photosynthesis.

Cells of green leaves-> Contain chloroplast organelles-> Filled with chlorophyll molecules-> Absorb light energy during photosynthesis

Photosynthesis involves 2 linked sets of chemical reactions:
1. The 1st is called the LIGHT-DEPENDENT REACTIONS
2. The 2nd set, which does the actual synthesizing of chemicals, is called LIGHT-INDEPENDENT or the CALVIN CYCLE.

In these 2 processes green organisms use energy from sunlight to make sugar.

Photosynthesis = Light-dependent reactions (produce energy) + Calvin Cycle (produce sugar)

– Light-Dependent Reactions are the conversion of light energy into chemical energy.
– In the first set of reactions, the chlorophyll absorbs energy that is striking the plants surface from sunlight. The Light-Reactions absorb the energy of sunlight and converts it to energy that is stored in chemical bonds.
– Once the light is absorbed the electrons of the chlorophyll become excited (a process where an electron gains energy). This energy absorption agitates the electrons within the chlorophyll. Some of these energized electrons are transferred where they can be used by the organism.
– The energy released from the electrons in the chlorophyll is used to do 2 things:
1. Split water molecules. When the water molecule is split, O2 (oxygen) is released into the atmosphere.
2. Make ATP. Some of the energy from the electrons in chlorophyll is used to change ADP to ATP.
– This energy is passed along until it reaches a particular pair of molecules that can process the energy. The energy released by the transferred electrons helps add a phosphate group to ADP, creating more ATP.
– Some of the produced ATP provides energy to run the 2nd stage of photosynthesis, the Calvin Cycle.
– As a result of the Light-Dependent Reactions, water is split and O2 (oxygen ) is given off. The plant uses some of the O2 for CELLULAR RESPIRATION and some is released into the atmosphere.

– The 2nd stage, called the Calvin Cycle, uses the ATP given off by the 1st set of reactions.
– This step involves the storage of chemical energy into sugar molecules.
– It is called a “CYCLE” because it begins and ends at exactly the same point: Carbon Dioxide (CO2) molecules.
– The Calvin Cycle takes place in the chloroplast. The simple inorganic molecules of CO2 (carbon dioxide) is used to make a complex organic molecule.
– In this step, CO2 (carbon dioxide) is chemically reduced from hydrogen ions and turned into a carbohydrate (sugar molecule/glucose).

CO2 (Carbon Dioxide) + H (Hydrogen Ions) = CH2O (Carbohydrate)

– One sugar molecule is to be used by the plant cell.
– Many plants make more sugar than they need; this sugar is converted to starch and stored in the roots, tubers and fruits of plants, food that other organisms eat.
– Most organisms need the food manufactured by green plants in the process of photosynthesis.

The following reaction summarizes the chemical process of Photosynthesis:

6 CO2(Carbon Dioxide) + 6 H2O(Water){REACTANTS} -> C6 H12 O6(Glucose) + 6 O2(Oxygen) + 6 H2O(Water){PRODUCTS}

Cellular Respiration

Where does the energy come from that power the recharging of the ATP molecule?

Cellular Respiration is a chemical process that occurs in all living cells, when trapped energy in the bonds of food molecules are converted to the stored energy in ATP molecules.

Cellular Respiration is a series of chemical reactions that frees the energy in food molecules, making it available to cells.

The chemical process of Cellular Respiration starts when a food molecule (i.e. glucose) enters the cell and is acted upon by the enzymes in the cytoplasm of the cell.

The steps of Cellular Respiration are controlled by ENZYMES.

This process takes place in the MITOCHONDRIA, in the presence of oxygen and is called AEROBIC RESPIRATION (oxygen requiring).

Respiration is generally defined as OXYGEN-REQUIRING; but respiration can also occur WITHOUT OXYGEN (ANAEROBIC RESPIRATION).

There are 2 steps to the Cellular Respiration Process:
– Glycolysis is the 1st series of chemical reactions in cellular respiration, in which glucose is converted to pyruvic acid.
– The entire process can take place whether or not oxygen is present. So Glycolysis is sometimes referred to as ANAEROBIC RESPIRATION.
– It is a series of reactions that take place in the CYTOPLASM of the cell.
– Each chemical reaction is catalyzed (to cause an action to begin) by an enzyme.
– The chemical reactions of glycolysis are anaerobic, because they occur without oxygen.
– All organisms can carry on glycolysis.
– Once GLUCOSE is present in the cell, its chemical bonds are broken down by glycolysis, with the help of enzymes, releasing free energy to make ATP.
– Glucose is not the only cellular fuel. ALL SIMPLE SUGARS in the diet are catabolized (process by which complex substances are converted to simpler compounds) and used in cellular respiration.
– To break down glucose, a small amount of energy is needed to get the reactions started, 2 ATP molecules supply this energy.
– In the initial reaction a glucose molecule is broken up into 2 new molecules of PYRUVIC ACID.
– Energy is released as the bonds of the glucose are broken to produce the 2 pyruvic acid molecules.
– During glycolysis one 6-carbon glucose molecule is broken down into two 3-carbon (pyruvic acid) molecules. Two ATP molecules are also produced.
– (1) 6-carbon glucose molecule -> (2) 3-carbon (pyruvic acid) molecules + (2) ATP molecules
– After the process of glycolysis has occurred, only about 10% of all available energy within the glucose molecule has been used.
– More energy can be extracted from the molecule, by using AEROBIC RESPIRATION.
– The KREB CYCLE is the aerobic process of cellular respiration.
– If oxygen is not present, the final product of glycolysis, PYRUVATE, is FERMENTED into ethanol and lactate.

2. There are 2 stages to AEROBIC RESPIRATION

– The 2 pyruvic acid molecules enter the Krebs cycle.
– The Krebs cycle takes place in the MITOCHONDRIA of the cell, where the enzymes that run the reactions of the Krebs cycle are located.
– The Krebs cycle is a repeating cycle of aerobic reactions that breakdown the pyruvic acids produced by glycolysis.
– The Krebs cycle rotate twice, once for each of the pyruvic acid molecules and produces 2 ATP molecules, several CO2 (carbon dioxide) molecules, and HYDROGEN-CARRIER MOLECULES.
– The hydrogen-carrier molecules move to the ELECTRON TRANSPORT CHAIN in the mitochondria.

– The molecules of the electron transport chain carry high-energy electrons from the hydrogen atoms down to lower and lower energy levels, releasing considerable amounts of energy along the way.
– A total of 34 more ATP molecules are produced from the electron transport process. The electron transport chain does not produce ATP directly, it produces a PROTON.
– The transported electrons, now deplete of most of their energy, are transferred to an OXYGEN ATOM.
– The oxygen atom combines with 2 hydrogen ions an creates WATER (H2O).
– C6 H12 O6 + 6 O2 -> 6 CO2 + 6 H2O + 36ATP
Glucose + Oxygen -> Carbon Dioxide + Water + Free Energy

When there is no oxygen available to complete the breakdown of glycolysis (the Krebs cycle requires oxygen) fermentation occurs.

Fermentation is the chemical release of energy from food without the use of oxygen.

The chemical process of fermentation does not release any more energy from the food (like the Krebs cycle and the electron transport chain) it only frees up molecules for continued respiration.

The process of converting pyruvate into ethanol and lactate is called fermentation.