Circulatory System Summer School

Question 1

Why do we need a circulatory system

Answer 1

→ All living organisms must obtain nutrients, get rid of waste and interact with their environment
↪ Not every living organism needs one as some can diffuse materials in and out
→ The circulatory system ensures gases, nutrients, etc delivered to every cell and that wastes are able to leave all cells

Question 2

Circulatory System Functions

Answer 2

→ Delivers O2 obtained by the respiratory system to all body cells
→ Delivers nutrients obtained by the digestive system to all body cells
→ Delivers hormones associated with the endocrine system to body cells
→ Removes metabolic wastes from the cells to the environment:
↪ CO2 from cellular respiration is delivered to the lungs to be exhaled
↪ Wastes filtered by the kidneys are delivered to the urinary system to be excreted
→ Maintains body temperature

Question 3

Closed vs Open Circulatory System

Answer 3

→ Humans have a closed circulatory system, where the blood is contained within a network of blood vessels
→ Some other animals have an open circulatory system, in which the fluid (called hemolymph – a mixture of blood and tissue) is pumped into an interconnected system of body cavities, where the cells are directly ‘bathed’ with the fluid

Question 4

Two Circuit Circulatory System

Answer 4

→ Pulmonary Circuit
↪ Circulates blood from the heart to the lungs for gas exchange and then back to the heart

→ Systemic Circuit
↪ Circulates blood from the heart to all the cells of the body to deliver oxygen, nutrients and other materials, and returns CO2 back to the heart

Question 5

Heart Composition: Tissue

Answer 5

→ Mostly made of a muscle called Myocardium
↪ Listed from outer to inner.
↪ Epicardium: Mainly made of connective tissue
↪ Myocardium: Mainly made up of Cardiac muscle tissue
↪ Endocardium: Mainly made of squamous epithelial.
→ Contains blood vessels, nerves and connective tissue
→ The heart is enclosed in a fibrous sheet called the Pericardium
↪ Made of dense connective tissue
↪ After the fibrous pericardium is the Parietal pericardium then a serous fluid and then a Visceral pericardium.
↪↪ The serous is fluid acts as a natural lubricant for the heart to beat without friction

Question 6

Heart: Basic Anatomy

Answer 6

→ The size of two fists clasped together
→ Weighs about 250 to 350 grams
→ In the middle of the chest in an area called the mediastinum area

Question 7

Heart: Chambers

Answer 7

The heart generates a high hydrostatic pressure to pump blood out of the heart, while also creating low pressure to bring it back in.

→ The heart has an inner division called the septum that creates four chambers. (This stops oxygenated blood from mixing with deoxygenated blood)

Two superior Atria (Low Pressure)
→ They receive the blood after it has travelled through the body
→ Thin-walled due to low pressure\
and
Two inferior Ventricles (High pressure)
→ Discharging chambers that push the blood back out.
→ Thick-walled due to high pressure

Each has its own one-way valve.

Question 8

Heart: Valves

Answer 8

Atrioventricular Valves (Separate Ventricles from Atrium)...
Tricuspid Valve: Between the right atrium and right ventricle

Mitral Valve (Bicuspid Valve): Between the left atrium and left ventricle

Semilunar Valves (Separate ventricles from arteries with blood leaving the heart)...
Pulmonary Semilunar Valve: A valve between the right ventricle and the pulmonary artery that allows the blood to flow from the heart to the lungs

Aortic Semilunar Valve: Between the left ventricle and the Aorta, helps carry the blood from the heart to the rest of the body

→ These control the flow of blood and prevent back flow

Question 9

Heart: Pumping the Blood

Answer 9

Pulmonary Circulation loop
1) Starts in the right ventricle. It pumps it through the pulmonary trunk (the only artery that carries deoxygenated blood and splits to form the left and right pulmonary artery) into the lungs to exchange CO2 for Oxygen

2) Then the pressure imbalance makes the blood want to go to a lower pressure area. Then it enters the left atrium via pulmonary veins.

Systemic Loop
3) Then the blood goes to the left ventricle via the one-way valve. The left ventricle contracts and the blood flows through your aorta to the rest of your body via the Aorta.

4) After the oxygen has been distributed, the blood enters the right atrium via the superior and inferior vena cava veins. Then the blood goes to the right ventricle and the cycle restarts.

Question 10

Heart: Systole and Diastole

Answer 10

DIASTOLE – the period when the ventricles are relaxed, blood is filling the ventricles (Diastolic pressure is the pressure in your arteries when the ventricles are relaxed)
SYSTOLE – the period when the ventricles contract, blood is pushed out of the ventricles (Systolic pressure is the peak pressure that is produced when ventricles contract)

Question 11

Heart: Lub and Dub

Answer 11

Lub: Mitral and Tricuspid Valves closing (The high pressure caused by ventricular contraction is called systole)

Dub: Pulmonary semilunar and Aortic Semilunar valve close why the other two open. (The pressures in the arteries when the ventricles are relaxed is called diastole)

Question 12

Heart: Cardiac Muscle

Answer 12

→ Heart muscle is made of specialized cells is called myocardium
→ Striated
→ Uses sliding filaments to contract and expand
→ Wide and board cells that usually branch out and are interconnected
↪ They are always connected electrically and physically. They need to be linked to have the right timing to create pressure gradients.
→ Has one to two central nuclei
→ Separated by a loose matrix called Endomysium which has a lot of capillaries to supply oxygen.
→ They have a lot of mitochondria which prevent fatiguing (25%-35% of the cell is mitochondria)

Question 13

Heart: Pacemaker cells

Answer 13

The pacemakers keeps your heart in rhythm, making sure that each muscle contracts at the right time. (Kinda like a heart’s brain)

Question 14

Heart: Intrinsic Cardiac Conduction System

Answer 14

1) Pace makers cells start off with sodium gates in leaky membranes letting in sodium ions until it reaches a certain voltage threshold.
↪ The leaking happens at a steady rate so it is like clockwork, the more leaky the cells the faster.
2) Heartbeat is initiated by a cluster of cells in the right atrium called the Sinoatrial (SA) node
Small mass of nerve and muscle
↪ Acts as a pacemaker, and signals normal rhythm of the heartbeat
3) Signal travels to a second node via synapse like connections called gap junctions. The node is called the AV node
↪ The signal is delayed by a bit to let the atria finish contracting before the ventricles do
4) From here, conducting fibres called Purkinje Fibres receive a signal to via the Atrioventricular bundle (runs down through the septum). These fibers are spread out through the muscles of the ventricles, signalling for them to contract

Question 15

Blood

Answer 15

→ An average 70kg person has 4-5 liters of blood
→ Made up of cellular components: Red Blood Cells, White Blood Cells and Platelets
→ Has an intracellular matrix component: Plasma
→ Accounts for 8 percent of body weight
→ A type of connective tissue

Transport and Distribute: Oxygen, Nutrients, Waste products and Hormones

Question 16

Blood: Plasma

Answer 16

→ Protein-rich liquid 90% water
→ Contains dissolved and other suspended (not dissolved) materials:
↪ Blood cells
↪ Oxygen
↪ Carbon dioxide
↪ Nutrients (glucose, amino acids, fatty acids, etc)
↪ Vitamins
↪ Hormones
↪ Dissolved ions (eg Na+, K+) - Electrolytes necessary for maintaining ph and osmotic pressure
↪Proteins (some involved in blood clotting, some involved in maintaining fluid levels in the blood and some involved in immune responses)
→ Makes 55% of blood

Question 17

Blood: Red Blood Cells (Erythrocytes)

Answer 17

→ Carry Oxygen and Carbon Dioxide
→ Make 45% of total blood volume
→ The RBC is a biconcave disc. Shape gives more surface area than a sphere. It also gives the cell the flexibility to stretch and contract through narrow capillaries which are less in diameter than the RBCs.
→ There is no nucleus when mature. This gives more room for hemoglobin
→ Each RBC Contains about 280 million hemoglobin molecules
→ RBCs have a 120-day lifespan
→ They die and are removed by the liver and spleen
→ How many RBCs you have circulating is controlled by a hormone

Question 18

Blood: White Blood Cells (Leukocytes)

Answer 18

→ Defend body from foreign microbes.
→ Nucleated
→ Multiple types of WBCs are produced in the bone marrow
→ Physicians can monitor the amount of WBCs in your urine and determine whether you are succumbing to an infection
→ Leukocytes act like independent, single-celled organisms.
→ The leukocytes include the phagocytes (macrophages, neutrophils), mast cells, eosinophils, basophils, and natural killer cells.

Question 19

Blood: Platelets

Answer 19

→ Help with blood Clotting
→ Do not contain a nucleus
→ Cell fragments produced from nucleated cells in the bone marrow
→ irregularly-shaped, colorless bodies
→ sticky surface lets them, along with other substances, form clots to stop bleeding.

Question 20

Blood: Hemostasis

Answer 20

When you are bleeding
Platelet System
1) Blood Vessel will constrict thanks to a vasoconstrictor, thromboxane, which is release by platelets at site of injury
2) Platelets gather at the site of injury to stop bleeding. This is called a white clot
↪ These platelets don’t clot normally, otherwise blood wouldn’t flow. When the endothelial cells lining the blood vessel rupture, collagen fibers are exposed. When platelets come in contact with these fibers they start to clot
↪ More thromboxane is released an vasoconstriction further occurs
Thrombin System
3) Fibrin proteins develop via a lot of cascading chemical reactions to provide reinforcement to the clotted platelets and blood cells start to get caught, forming a red clot.
↪ Think of fibrin as long sticky strands
↪ Remember that blood has a clotting factor (Thromboplastin). The thromboplastin combines vitamin K and calcium ions which causes plasma proteins (Prothrombin) to convert into an active enzyme (Thrombin).
↪ Fibrinogen is the inactive part that becomes fibrin. These monomers have caps on F-2-F binding sites, once the caps are removed the monomer can form a fibrin polymer. Thrombin and calcium help the monomers join to form fibrin bonds.
↪ Fibrin form a loose meshwork stabilized by clotting factor 13.
4) Eventually the fibrin protein contract and pull the ruptured parts of the blood vessel together so that the endothelial can regenerate.

Question 21

Blood Types

Answer 21

→ Each blood group is characterized by the presence or absence of particular glycoprotein markers (Antigens) on the RBC membranes – the protein markers are either A or B
→ The body is fine with its own markers but will send antibodies to mark cells for destruction that have a foreign antigen.
→ There are 4 different basic blood types: A, B, AB and O
Then there are different Rh (Rhesus: Named of the species of monkey that they were identified in) antigens types
→ Rh-positive
↪ RBCs contains the Rh protein
↪ common
→ Rh-negative
↪ RBCs don’t contain the Rh protein
↪ Less common
→ Individuals who are Rh-negative may donate their blood to, but should not receive blood from, individuals with Rh-positive blood
→ Type AB are universal recipients and O is universal donors.

Question 22

Blood: Hemoglobin

Answer 22

→ Oxygen-carrying molecule in RBCs
→ There are 4 iron atoms per hemoglobin
→ Oxy-hemoglobin complex gives blood the red colour (interaction between iron and oxygen)
→ Made of 4 Heme pigments and 4 Globin proteins (2 Alpha Globins and 2 Beta Globins)

Question 23

Blood: Hematopoiesis

Answer 23

→ Happens in red bone marrow that is made of reticular connective tissue and has special capillaries called sinusoid capillaries

Process…

1) Hemocytoblast - Specialized Stem Cell
2) Proerythroblast - Differentiated cell
3) Early Erythroblast - Makers a whole bunch of ribosomes which start making a lot of hemoglobin
4) Late Erythroblast - Keeps producing hemoglobin but ribosome production is mostly finished
5) Reticulocyte - Lost nucleus and some ribosomes causing the cell walls to cave in a bit. This has a little group of ribosomes left called the reticulum
6) Mature RBC - The reticulocyte has produced enough hemoglobin, ribosomes have degraded and cell has entered blood stream.

Question 24

Blood Regulation using Protein

Answer 24

→ Blood is regulated using a protein called Erythropoietin (EPO)
→ Produced mostly in kidneys and sometimes in the liver.
→ If blood oxygen levels drop, the cells in the kidney will notice via Hypoxia-inducible factor (A chemical that monitors blood oxygen levels)
↪ The special kidney cells need oxygen to break down these molecules, if they are a lack of oxygen molecules, they will keep producing EPO which stimulates the red bone marrow to produce more blood cells

Question 25

Blood cell death

Answer 25

WBCs ambush the old erythrocytes via phagocytosis near the spleen to recycle their components.

Question 26

Blood Vessels

Answer 26

Active organs that are capable of expanding and contracting to carry out the functions…

1) Deliver oxygen and nutrients to the cell
2) Carry away waste products
3) Help maintain blood pressure.

Question 27

Types of Blood vessels

Answer 27

Veins and Venules: Carry blood towards the heart
↪ Venules are mini-veins that suck out the blood from the capillaries
Arteries and Arterioles: Carry blood away from the heart
↪ Arterioles are mini-arteries that branch into the capillaries
Capillaries: Areas where oxygenated blood becomes deoxygenated. Think of it as a transfer station between the veins and capillaries

Question 28

Blood Vessel Parts

Answer 28

Lumen: Inside of the blood vessel where all the blood flows

Tunica Intima: Made of Endothelium(squamous epithelium tissue), connective tissue and internal elastic membrane.
→ The endothelium secretes mucus to make sure that the blood can flow without friction

Tunica Media: Made of smooth muscle cells and protein elastin.
→ Responsible for contraction (Vasoconstriction) or expansion (Vasodilation)
→ The smaller the diameter of the blood vessel, the harder it is for the blood to move through it. This is helpful to slow down the blood and lower the pressure so that it does not burst the smaller blood vessels.

Tunica Externa: Made of loosely woven collagen fibre

The aorta has the most elastin of any blood vessel.

Question 29

Capillary Parts

Answer 29

Capillaries link the arteries and veins together at conjunctions.

→ Thin walls (Single layer epithelial tissue) and are narrow, where diffusions of oxygen, carbon dioxide and other wastes occur.
→ These capillaries are connected to venules and arterioles which are basically smaller arteries and veins.
→ If it is cold, sphincters will form and close off some capillaries, so that the blood is not exposed to the cold and less heat is lost. (thus numbness)
↪ If this gets to a certain point, your arteries and veins will constrict to lower blood flow and lose less heat.
↪ On the contrary, if you are working a certain body part, the vessels will expand to let blood flow.

Question 30

Capillary Roles

Answer 30

Form capillary beds to preform
1) Exchange nutrients
2) Help regulate blood pressure
3) Play a role in thermoregulation
↪ When it is cold certain capillaries will be cut of to prevent the blood from being exposed to the cold via sphincter

Question 31

Veins

Answer 31

→ Always carry blood towards the heart
→ Wall of these blood vessels are less muscular than arteries but they are more flexible
→ Therefore, the internal diameter of veins is larger than that of arteries and blood pressure is lower in veins than arteries
→ Large veins contain valves (Venous Valve) to prevent blood backflow
→ Usually carries deoxygenated blood (exception: pulmonary vein)
→ Capillaries lead to smaller versions of veins called venules, which lead to the veins

Question 32

Arteries

Answer 32

→ Always carry blood away from the heart at high pressure
→ Usually carries O2 - rich blood (exception - pulmonary artery)
→ Consist of 3 layers to accommodate this high pressure:
→ Some made up of smooth muscle cells and elastic fibres that make the walls tough and flexible
largest artery is the aorta which carries oxygenated blood from heart to the entire body
→ Arteries branch into a smaller version called arterioles, which lead to capillaries ‘
→ Diameter of arterioles is controlled by nerves, which controls blood flow to different parts of the body

Question 33

Blood Vessel Diseases: Hypotension

Answer 33

→ Condition when blood pressure is abnormally low
→ Rare
→ Symptoms: Dizziness, tired, lacking energy

Question 34

Blood Vessel Diseases: Hypertension

Answer 34

→ When there is very high blood pressure
→ Symptoms: Headache, Confusion, Sleepiness, Coma
→ Complications: Atherosclerosis, Heart attack, Heart failure, Kidney failure, Eye damage and Aneurysm (expansion of a main artery, which becomes weakened and may rupture)

Question 35

Blood Vessel Disease: Atherosclerosis

Answer 35

→ Hardening of arteries due to the buildup of plaque inside the walls of the Arteries
↪ Plaque - deposits of fat, cholesterol, calcium and other minerals on the walls of arteries

→ Treatment: Angioplasty surgery
↪ 1) A catheter which is equipped with a small inflatable near its end and a metal mesh-self expanding tube called a stent is inserted into the artery
↪ 2) When the balloon reaches the narrow area, it is inflated with liquid or gas to stretch the artery and widen the stent
↪ 3) The catheter is removed, leaving the stent in place. Over time cells grow over the stent.

Question 36

Blood Vessel Disease: Coronary Artery Disease

Answer 36

→ Buildup of plaque on or in one of the coronary arteries
↪ This can lead to heart attack

→ Treatment: Bypass Surgery
↪ A surgical procedure in which arteries are grafted to blocked or narrowed coronary arteries in order to reroute blood flow and oxygen to the heart
↪↪ Most commonly grafted/rerouted from the leg
(Grafting is basically taking a blood vessel from another part of the body and then using it to reroute blood flow around the blockage)

Question 37

Blood Pressure

Answer 37

→ Blood pressure is the force of the blood on the walls of the arteries.
→ If the amount increases, the pressure on the walls of the artery will increase
↪ Many increases can be tolerated because the artery walls have elasticity, which exerts an opposite force on the blood
→ When the blood vessels are stretched to the limit, the increased pressure can cause more serious health effects

→ Each time the ventricles contract, a surge of pressure is pumped into your arteries 🡪 this is the systolic pressure
↪ Normal systolic pressure in a young adult is 120 mm Hg
→ In between ventricular contractions, the chambers of the heart are filling with blood 🡪 this is the diastolic pressure
↪ Normal diastolic pressure in a young adult is 80 mm Hg

mm Hg is millimeters of mercury.

Question 38

Why does blood pressure decrease in veins

Answer 38

→ When blood leaves the arterioles and flows into a network of capillaries there’s a decrease in the rate at which blood flows
→ This is because the total surface area of all the capillaries is significantly greater than the surface area of the arteriole from which the blood is entering
→ As a result, the blood pressure has decreased so much by the time it enters the veins

Question 39

Blood: Anemia

Answer 39

A deficiency in hemoglobin or RBC which decreases oxygen delivery to tissue
→ Associated with low energy levels
→ Can be diet related (low-iron diet)

Question 40

Blood Clotting (Coagulation)

Answer 40

→ Internal blood clots are a bruise
↪ Both scabs and bruises are clots that lead to healing.

→ Some clots can be extremely dangerous.
↪ A blood clot that forms inside of a blood vessel can be deadly because it blocks the flow of blood, cutting off the supply of oxygen (thrombosis)

→ A stroke is the result of a clot in an artery of the brain.
↪ Without a steady supply of oxygen, the brain cannot function normally.
↪ f the oxygen flow is broken, paralysis, brain damage, loss of sensory perceptions, or even death may occur.