blood where is goes, how it goes and why it goes!

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Blood Where is goes, how it goes and why it goes!

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Blood

Where is goes, how it goes and why it goes!

The Components of Blood

If 10ml of blood is taken from a blood

vessel in your

arm…

…and is left to

stand, it soon

settles into 3

observable layers.

45% Red blood cells - erythrocytes

0.1% White blood cells - leucocytes.

55% Plasma

A thin layer of platelets (0.01%) settles between the red and white cells – this is difficult to see with the naked eye.

The Components of BloodRed Blood Cells -

Erythrocytes

•Red blood cells have a biconcave shape like donuts with the center filled in.

•They are made in the bone marrow, and soon after development lose their nucleus.

•They can live for about 3 months.

•They are about 7-8 m in diameter and 1-2 m in thickness.

•Each RBC contains 200-300 million haemoglobin molecules, which gives them their characteristic colour.

The Components of Blood Haemoglobin - Structure

•Haemoglobin is a complex molecule made up of two main parts; the protein part (the globin), made of 4 polypeptide chains, and the haeme group (which contains iron) that is inside each folded polypeptide.

•Four oxygen molecules can be carried by each haemoglobin molecule. Once 4 oxygen molecules have combined, each with an iron ion, the molecule is known as oxyhaemoglobin. Hb + 4O2 > Hb(O2)4

•The oxygen bonds easily allowing it ‘click’ in and out of the haemoglobin molecule easily depending on the surrounding concentration of oxygen.

The Components of Blood Haemoglobin - Function

•Haemoglobin transports oxygen from areas of high oxygen concentration (the alveoli) to areas of low oxygen concentration (the surface of cells).

•It can also transport some carbon dioxide – although most travels in the plasma as a carbonate ion.

•Acts as a buffer in the blood by absorbing hydrogen ions that are left in the plasma when carbon dioxide reacts with water to from hydrogen carbonate ions. This prevents dramatic changes in blood pH that would affect normal metabolism.

The Components of Blood Haemoglobin – adaptive

advantages1. Because haemoglobin increases the amount of oxygen that

can be carried in the blood, it is an adaptive advantage for organisms that need a large supply of oxygen.

2. The structure of haemoglobin is also an adaptive advantage because it loosely binds to oxygen at the respiratory surfaces and easily releases oxygen from the capillaries near the cells of the body that require it.

3. If oxygen were to be transported in the plasma rather than attached to haemoglobin inside a red blood cell, it would change the osmotic balance of the blood.

4. The red blood cell is thought to loose its nucleus shortly after development so that a greater number of haemoglobin molecules can fit inside the cell membrane.

The Components of BloodWhite Blood Cells -

Leucocytes•White blood cells are made in the bone marrow and can live for days or months.

•They are part of our immune system and help defend our bodies against infection. They can move out of the blood stream to the interstitial fluid in order to help fight infections. They are then collected by the lymph and returned to the blood stream.

•White cells that engulf foreign bodies are called phagocytes.

•There are many different types and they all have different functions.

•They range in general size from 10m to 20m and are less numerous than red blood cells.

Neutrophil

Monocyte

Lymphocyte

Eosinophil

Basophil Phagocyte

The Components of BloodPlatelets

•Platelets are fragments of cells that are also made in the bone marrow.

•They are smaller than red and white cells – only 3m is diameter and live for about 1 week.

•They are important in helping the blood to form clots in order to stop bleeds.

Platelet in amongst red blood cellsPlatelets forming a

clot

The Components of BloodPlasma

•Plasma is straw coloured and is made up of about 90% water.

•Plasma suspends all blood cells.

•Carries many other sustances such as carbon dioxide, urea, salts, amino acids, vitamins, hormones.

•Helps keep the pH of blood at 7.4

•Helps keep osmotic pressure of blood stable.

•Promotes clotting.

The Blood Transports other Substances Carbon

Dioxide•CO2 is metabolized in the mitochondria during cellular respiration. It then diffuses into the capillaries where it is taken back to the heart and then pumped to the lungs so that it can be expelled during exhalation.

•Carbon dioxide in our plasma reacts with the water to produce carbonic acid hydrogen carbonate ions, HCO3-. The reaction is as follows: CO2 + H2O > H2CO3 > H+ + HCO3-

•HCO3- increases the acidity of the blood (therefore it decreases the pH of the blood). This can be tested in the lab by simply bubbling CO2 through some water and noting the pH before and after.

•Buffers act to adjust the pH of solutions. There are buffers in the plasma that help to regulate the pH of the blood to 7.35-7.45 even though there are small amounts of CO2.

•If the concentration of CO2 becomes too high (such as during exercise) it stimulates the breathing center in the brain. Nerve impulses are sent to the diaphragm and intercostal muscles in the ribs to expand the chest so that the lungs fill with air and breathing rate and the depth of breathing is increased.

The Blood Transports other SubstancesCarbon Dioxide - regulation

Stimulus:

Increase in CO2

levels in the blood

RECEPTOR: CO2 receptors in aorta

and carotid arteries

Transmits information

to..

CONTROL CENTRE: Breathing control system in medulla

in CNS Nerves activate…

EFFECTOR: rib muscles

and diaphragm

RESPONSE: rate of breathing

increases

Stimulus: CO2 levels in blood

reduced

The Blood Transports other Substances Oxygen

•Oxygen is carried as itself by the haemoglobin molecule in red blood cells.

•It enters the blood stream as it crosses the thin membranes of the alveoli. It is taken to the heart where it is then pumped around the body to all cells. It crosses the membrane of the cell from the capillary. Inside the cell it is used in (aerobic) cellular respiration to produce energy.

•The red blood cells need to deliver a constant supply of oxygen to cells or they will die.

The Blood Transports other Substances Water

•Water is transferred from the digestive system to the cells via the circulatory system.

•Blood plasma is about 90% water, so essentially the plasma transports the water.

The Blood Transports other Substances Salts

•Salts are made up of ions of a metal and a non-metal and include sodium chloride, potassium chloride, magnesium sulphate and so on.

•The ions of salts form when the salt dissolves in water. Examples include sodium ions, potassium ions, magnesium ions, chloride ions, sulphate ions and phosphate ions.

•These ions are transported from the digestive system to the cells via the circulatory system.

•The ions are transported suspended in plasma.

The Blood Transports other Substances Lipids

•Glycerol and fatty acids travel around the body suspended in the plasma.

•They move from the digestive system to the liver via the circulatory system.

The Blood Transports other SubstancesNitrogenous Wastes

•Urea is the main form of nitrogenous wastes in humans. Small quantities of ammonia and uric acid are also transported around the body in the plasma.

•Nitrogenous wastes are transported from the liver and body cells to the kidneys. From the kidney they are excreted from the body.

The Blood Transports other SubstancesOther products of

digestion

•‘Other products’ of digestion include amino acids and glucose.

•They are transported around the body in the plasma.

•They are transported from the digestive system and the liver to the body cells.

The Blood’s Journey Around the BodyArtery – structure &

functionTwo outer layers of muscle surround the artery

Strong elastic fibers

Inner lining of cells – epithelial layer

Arterial cavity/lumen•Arteries carry blood away from the heart.

•Small arteries (just before they become capillaries) are called arterioles.

•They carry oxygenated blood to the body via the aorta and deoxygenated blood to the lungs via the pulmonary artery.

•The blood in arteries in under a great deal of pressure as it is being pumped from the heart.

•Arteries do not have valves.

•Arteries have thick muscular elastic walls that can expand and recoil when blood is pumped through it.

The Blood’s Journey Around the BodyVein – structure &

functionMuscle layers

Thin lining of cells – epithelial layer

Vein cavity/lume

n•Veins carry blood to the heart.

•Small veins (just after the capillaries) are called venules.

•They carry deoxygenated blood back from the body via the vena cava and oxygenated blood from the lungs via the pulmonary vein.

•Veins are thinner walled than arteries but larger in diameter.

•The blood in the veins is under low pressure as it is a long way from the pressure of the pumping action of the heart.

•Movement of blood back to the heart from the body is assisted by muscular contraction. Valves prevent the back flow of blood.

x200

The Blood’s Journey Around the BodyVein and Artery - structure

Heart muscl

e

Artery

Veins

The Blood’s Journey Around the BodyCapillary – structure & function

Wall of capillary is one cell thick. It is an extension of the epithelial layer in veins and arteries. The thin wall creates a large surface area to volume ratio which allows for easy diffusion of oxygen and carbon dioxide at the surface of the cell. No cell is too far from a capillary.

The cavity where blood travels is a lot thinner

(8m) than the cavity of a vein, venule, arteiole

or artery, this means the blood is under

greater pressure and often causes cells to

distort. The increased pressure facilitates

diffusion of oxygen and carbon dioxide.

•Capillaries are the thinnest blood vessels

•They connect venules to arterioles and arterioles to venules

•Capillaries are next to every cell in the body.

The Blood’s Journey Around the BodyBlood Flow – a double circulatory

system

Gas exchange at the alveoli. Oxygen moves into the circulatory system, carbon dioxide is deposited into the lungs for excretionGas exchange at the cells

of the body. Oxygen moves into the cell and carbon dioxide moves out of the cell and into the capillaries. Fluids and wastes such as urea also leave the blood in the systemic system.

Pulmonary system – moves blood from the heart to the lungs under lower pressure

Systemic system – moves blood from the heart to the rest of the body under high pressure

Early experiments to show that some blood flows to the heart and some away

The Blood’s Journey Around the BodyThe Heart – a double

pump•The heart consists of 2 pumps, one is made up of the left atrium and left ventricle and the other is made up of the right atrium and right ventricle.

•Blood is pumped in a one way direction (controlled by valves) and oxygenated and deoxygenated blood does not mix. Follow the flow below…

Right atrium

Inferior vena cava brings

deoxygenated blood from the

body

Right ventricle

Pulmonary arteries take deoxygenated blood to the lungs to pick up oxygen and deposit carbon dioxide

Pulmonary vein brings oxygenated blood back from the lungs

Left atrium

Left ventricle

Aorta takes oxygenated blood to

the body

Strong muscular contractions pump the blood

Valves prevent backflow of

blood

The Blood’s Journey Around the BodyMain Changes in the Chemical Composition of

Blood•Carbon dioxide and oxygen are constantly changing in concentration as they are either being used by the body (oxygen) or created by metabolism (carbon dioxide).

•Water diffuses into the blood when water concentration becomes too low. It can diffuse in from the large intestines or the kidney. Excess water is removed from the blood stream and excreted.

•Drugs, such as alcohol, can pass into the blood stream from the digestive tract.

•Digested foods such as amino acids, fatty acids and glucose diffuse into the blood. The liver removes excess glucose and amino acids (which it converts to urea). Fatty acids are transferred to the lymph.

•Salts and vitamins are absorbed in large intestine and pass into the blood. Excess salts are removed and excreted.

•The endocrine glands secrete hormones into the blood stream.

Donated Blood

•If you have ever donated blood you will already be aware that it takes about 15 minutes to remove about 0.5 L of blood from your arm.

•The blood is packaged up and labeled in clear plastic bags.

•Each package is tested for blood type and also for a range of infectious diseases such as HIV, hepatitis and syphilis.

•When a patient has blood taken for their own use later down the track, it is known as an autologous donation.

•When someone donates blood for someone else it is known as a standard donation.

Donated Blood

•Whole blood is only used for transfusions when a patient has lost more than 20% of their blood volume.

•Otherwise, donated blood is usually broken down into its various components; red cells platelets, plasma, white blood cells.

•Red blood cells are used to treat anaemia patients due to their bone marrow not making enough red blood cells or because they have lost a lot of blood. The extra red cells means more haemoglobin and more oxygen.

•Plasma is given to patients with clotting disorders such as haemophilia.

•Platelets are given to patients who usually have cancer of the blood and do not have enough platelets to allow the blood to clot.

•White blood cells are used to treat patients with life threatening infections along with low white cell counts.

The End