Unit 6 - Circulation

Why are specific transport systems necessary in large multicellular organisms but not in unicellular ones?

"The exchange of substances between small, unicellular organisms is done through diffusion, osmosis & active transport but in large multicellular organisms like Homo Sapiens, the exchange of substances with other cells & their external environment becomes harder as they become more widely separated, that's why specific transport systems were developed"

"Mention 4 organisms which don't have specific transport systems."

Amoeba, paramecium, flatworm & euglena

What are the 4 components of blood?

Plasma, erythtrocytes, leucocytes & platelets

What is plasma?

"It's a yellow liquid which contains many dissolved substances like blood cells, food, urea, antibodies & waste products (carbon dioxide, hormones, dissolved glucose for respiration, dissolved salts & enzymes) and plasma proteins"

What are plasma proteins?

"They're proteins soluble in the blood plasma"

What are 3 plasma proteins commonly found in the blood?

Albumen, globulin & fibrinogen

What is albumen?

"It's a plasma protein that makes the blood more thick & viscous"

What is globulin?

"It's the protein that destroys germs & from which antibodies are made and it's produced by lymph cells"

What is fibrinogen?

"It's a plasma protein responsible for blood clotting"

What are the 3 most common blood cells in the body?

Erythrocytes & leucocytes (lymphocytes & phagocytes)

What are erythrocytes?

"They're the most numerous cell in the body and made in bone marrow."

What are the adaptations of an erythrocyte?

"It has the red pigment haemoglobin which binds to oxygen forming oxyhaemoglobin and carries it to the cells in need. It also lacks a nucleus to maximise the space for oxygen and has a biconcave shape to maximise it's surface area for oxygen absorption."

How long is the life span of an erythrocyte?

120 days

What are leucocytes?

They form part of the immune system, keeping us safe from infection & disease and like erythrocytes, are also made in bone marrow.

What is the lifespan of a leucocyte?

3 weeks

What is a phagocyte?

"It's a leucocyte characterised by the presence of a lobed nucleus. It moves about thanks to a flowing action by its cytoplasm which contains several enzymes that engulf pathogens. It's function is to remove large foreign pathogens that may invade the body and cause disease, alas they have a sensitive cell surface membrane."

What is a lymphocyte?

"It's another type of leucocyte which produces antibodies which stick pathogens together, making it easier for the phagocytes to destroy them. It can also form antitoxins against poisons produced by pathogens"

What are antibodies?

"They're proteins made by lymphocytes that attach to antigens & neutralise toxins produced by pathogens. They could also cause bacteria to burst open & die, label pathogens by attaching themselves to it making it easier for the phagocyte to locate and stick pathogens together in clumps so that they're englufed by phagocytes more easily"

What are antigens?

"They're substances found on the surface of cells, including bacteria & other pathogens. Specific antibodies attach to specific antigens, and that's how the body's immune system can recognise foreign antigens. The more an antigen attacks your body, the easier it gets for lymphocytes to produce the specific antibodies. This also applies to vaccines"

What are platelets?

"They're small, colourless cell fragments involved in the process of blood clotting as they form scabs to stop wounds from bleeding. They're also made in bone marrow."

What is the word equation for blood clotting?

\(\ce{Prothrombin (soluble protein in plasma)-\>[Thromboplastin (from breakdown of blood platelets)][Calcium Vitamin K]Thrombin (protein digesting enzymes)}\)\(\ce{Fibrinogen (soluble protein in plasma) -\>[Thrombin]Fibrin (insoluble sticky protein fibre in the form of a net that heals the skin)}\)

What are 3 functions of the blood?

To transport, regulate & protect

How is the function of the blood to transport?

It carries oxygen from the lungs, where the haemoglobin becomes oxyhaemoglobin, to the tissues, where oxyhaemoglobin becomes haemoglobin as oxygen diffuses into the tissue cells. It also collects carbon dioxide & carries it in solution as sodium hydrogen carbonate, carries dissolved food substances from the gut to other parts of the body, carries hormones from endocrine glands to other parts of the body & carries antibodies from one part of the body to another.

How does the blood aid in regulation?

It helps maintain a static body temperature of 37°C by absorbing or losing heat at the surface of the body & distributing evenly around the body and helps control the amounts of various chemical substances in the tissues

How does the blood help in protection?

It contains leucocytes which protect against disease and prevents fluid loss & the entry of foreign pathogens from cuts & wounds through blood clotting

Which blood grouping method is most commonly used?

The ABO method is most commonly used

What are the 4 main blood groups?

A, B, AB & O

Why do we categorise blood in groups?

Different people have different antigens on their erythrocytes & different antibodies in their blood for the antigens not possessed by the erythrocytes

How many antigens are there?

There are 2, Antigen A & Antigen B

How is a person classified into a blood group?

"If antigen A is present on the erythrocytes & there are antibodies for antigen B, then the person is classified into blood group A and the same goes for blood group B. If you have both antigen A & B, then you're in blood group AB & you don't have antibodies A or B and if you don't have any antigens at all but antibodies A & B then you're in blood group O"

Why is it important to know what blood group people belong to?

Blood donations could be made safely without causing harm to the recipient. If the incorrect blood type is given to the recipient, agglutination would occur as the donated blood would be attacked by the body & cause a blood clot, resulting in death.

Why are people belonging to blood group O universal donors?

"Their erythrocyts don't have any antigens thus no immune response is created to fight them off"

"What's the Rhesus factor?"

"It' an additional marker in the blood. People who possess the antigen called the rhesus factor are termed rhesus positive & does who don't possess this antigen are rhesus negative."

What happens if rhesus positive blood is donated to a rhesus negative individual?

The recipient would produce rhesus antibodies

"Where does your blood get it's red pigment from?"

It gets it from your erythrocytes

What are the 3 components of the circulatory system?

A system of tubes (blood vessels), a pump (heart) & valves (prevent backflow)

What are the 3 blood vessels?

Arteries, veins & capillaries

What is an artery?

"It's the vessel that carries oxygenated blood to the body with the exception of the pulmonary artery which delivers deoxygenated blood to the lungs. It has thick, muscular walls & a small internal lumen as it contains blood under high pressure. It also branches out into arterioles & capillaries"

What is a vein?

"It's the vessel that carries deoxygenated blood to the heart with the exception of the pulmonary vein which delivers oxygenated blood from the lungs to the heart. It has thin walls & a large internal lumen as it contains blood under low pressure. Veins also have valves to prevent the backflow of blood"

What is a capillary?

"It's a vessel made of endothelial cells found in the muscles, lungs & other parts of the body and it's microscopic. It contains blood under low pressure and it's a gaseous exchange surface as oxygen & carbon dioxide diffuse easily into & out of it"

What is the heart?

"It's an organ made of cardiac muscle whose function is to pump blood around the body"

What are atria?

"They're the place where blood collects when it enters the heart. The left atrium receives blood from the pulmonary vein whilst the right atrium receives blood form the vena cava"

What are ventricles?

They pump bloos out of the heart & to the lungs or around the body. The left ventricle pumps blood at a high pressure to the aorta whilst the right ventricle pumps blood to the pulmonary artery

What is the septum?

It separates the right & left side of the heart to prevent the contamination of blood. The left side of the heart is also slightly thicker as it contains blood under higher pressure than the right side

"What's the tricuspid valve?"

"It's located between the right atrium & the right ventricle and opens due to a build-up of pressure in the right atrium"

"What's the bicuspid valve?"

"It's located between the left atrium & the left ventricles and opens due to a build-up of pressure in the left ventricle"

What are the semilunar valves?

"These valves prevent the backflow of blood into the heart, one's situated between the right ventricle & the pulmonary artery and the other one is situated between the left ventricle & the aorta"

What are coronary arteries?

"They're the arteries that supple blood to the heart"

What are the 4 blood vessels surrounding the heart?

Aorta, vena cava, pulmonary artery & the pulmonary vein

"What's the aorta?"

"It's the largest artery in the body & carries oxygenated blood from the left ventricle to the body"

"What's the vena cava?"

"It's the largest vein in the body & carries deoxygenated blood from the body to the right atrium"

"What's the pulmonary artery?"

It carries deoxygenated blood from the right ventricle to the lungs

"What's the pulmonary vein?"

It carries oxygenated blood from the lungs to the left atrium

"What's an atrial diastole?"

"It's the moment when the atria & ventricles are both relaxed as deoxygenated blood enters the right atrium at a low pressure through the vena cava and oxygenated blood enters the left atrium at a low pressure through the pulmonary vein. At this time, both the tricuspid & bicuspid valves are closed until they open up due to immens pressure"

"What's an atrial systole?"

After the atrial diastole, the 2 atria have to contract simultaneously to push blood into each respective ventricle

"What's a ventricular systole?"

Once the ventricles are full, the atrioventricular valves close creating a lub sound to prevent blood from returning to the atria. The pressure opens the semi-lunar valves and blood is distributed to the blood vessels.

"What's a ventricular diastole?"

After the ventricular systole, the semi-lunar valves close to prevent any backflow of blood from the vessels

Which blood vessels surround the lungs?

The pulmonary artery & the pulmonary vein

Which blood vessels surround the liver?

The hepatic artery & the hepatic vein

Which blood vessels surround the kidneys?

The renal artery & the renal vein

"What's double circulation?"

Humans have 2 separate circuits; the pulmonary circuit between the heart & the lungs and the systemic circuit between the heart & the body. Blood also passes through the heart twice

Why is double circulation vital?

"It's vital so as to deliver oxygenated blood to all of the organs around the body and also as to collect carbon dioxide & other waste substances from around the body and get rid of them"

Cardiologically, what occurs during physical exercise?

Exercising muscle require more energy than usual thus respiration must occur more frequently and more oxygen & glucose are needed. More carbon dioxide is also produced. To cater the demands of exercise, the heart rate/pulse rate increases, sending out blood more frequently and so does the stroke volume which sends out more blood overall

Where can the heart rate be monitored from?

The outer side of the wrist or inner corner under the jawline

Apart from exercise, what else might cause a spike in heart rate & stroke volume?

When stressed, angry or afraid, adrenaline would be released and increases our heart rate & stroke volume preparing us for fight of flight

What are the main benefits of exercise?

Regular, consistent exercise would result in added muscle tissue & an increase in metabolic rate as muscle tissue requires more energy to be transferred from food, decreasing the probability that the person becomes overweight. There would also be a reduction in the risk of developing: fatty deposits in the coronary arteries, heart disease, diabetes & high blood pressure. It could also result in fitter hearts with a better blood supply and larger lungs.

What is coronary heart disease?

"It's the blockage of the coronary arteries by cholesterol plaques which results in abnormal blood flow & higher blood pressure"

What are some possible causes of heart disease?

Poor diet (saturated fats increase cholesterol levels), stress & smoking (increase in blood pressure & fatty deposits) and a lack of exercise & being overweight

How is blood pressure created?

When the heart contracts, it pusches blood into the blood vessels, creating blood pressure

What are the 2 values one obtains from a blood pressure reading?

Systolic value (contracted heart) & diastolic value (relaxed heart)

"What's the average adult blood pressure"

120/80mmHg

What is blood pressure determined by?

By the cardiac output (Q) & the resistance to flow (R - caused by the diameter of blood vessels & the thickness of the blood)

What is atherosclerosis?

A condition where there is plaque build-up in the arteries, increasing the resistance to flow & blood pressure. This condition could ultimately result in chronic high blood pressure, angina (pain in the thorax), heart attack or stroke

What is tissue fluid?

"It's a colourless, nutritive watery fluid found between cells in the tissues. Since plasma proteins & blood cells cannot pass through capillaries, tissue fluid would be in charge of bathing the cells & keeping them in the right condition, in fact cells get all the substances they need from the bloodstream via the tissue fluid. Any excess tissue fluid returns to the blood capillaries or drains into lymph vessels that make up the lymphatic system becoming lymph."

What is the lymphatic system?

"It's a system of numerous, thin-walled lymph vessels which take lymph to the blood stream as they're connected to the subclavian vein near the heart. Valves in the lymph vessels and various muscle contractions keep the lymph moving to the veins as lymph flow is quite slow since there is no pumping organ. One may also find various lymph nodes/glands at intervals along the length of the vessels (sides of the neck, armpit & groin) which contain a meshwork comprising of several lymphocytes & phagocytes. Lymph tissue may also be found in the tonsils & adenoids in the throat"

"What's the function of the lymphatic system?"

It returns lymph to the blood, maintaining a constant concentration of the blood & preventing fluid build up in tissues, helps in fighting disease as it produces lymphocytes and it absorbs & transports lipids from the small intestines (lacteals found in villi are seen white at times due to minutes liquid droplets found inside of them).