Circulation

what is hypertension?

high blood volumel caused by constricted blood cells

myocardium

thickest layer of muscle of the heart, does most of the mechanical work

• contracts to pump blood throughout the body

frq 6a: Compare the chemical composition of blood inthe right atrium of a fetus to the blood in the right atrium of an adult. Provide reasons for your answer.

The blood in the right atrium of a fetus contains a mixture of oxygenated and deoxygenated blood. This is because oxygenated blood from the placenta enters the fetus through the umbilical vein and largely bypasses the liver via the ductus venosus, flowing into the inferior vena cava. There, it mixes with deoxygenated blood from the fetus’s body before entering the right atrium.

• the right atrium of an adult receives only deoxygenated blood from the body through the superior and inferior vena cava, since adults do not have an umbilical vein supplying oxygenated blood, and all oxygenation occurs in the lungs.

frq 6b : Detail three key differences between fetal and adult circulation, and how they change at birth.

Fetal circulation includes special structures that allow blood to bypass the liver and lungs, which are not fully functional before birth. Three major differences are:

ductus venosus: allows oxygenated blood from the placenta to bypass the liver and flow directly into the inferior vena cava. After birth, when the umbilical cord is cut, the ductus venosus closes and becomes a ligament.

Foramen Ovale – This is a hole between the right and left atria that allows blood to bypass the lungs by flowing directly from the right atrium to the left atrium. When the baby takes its first breath, pressure in the left atrium increases, causing the foramen ovale to close permanently.

Ductus Arteriosus – This vessel connects the pulmonary artery to the aorta, letting most blood bypass the fluid-filled lungs. After birth, the ductus arteriosus closes and becomes the ligamentum arteriosum due to changes in oxygen levels and pressure.

In addition, deoxygenated blood is carried to the placenta via the umbilical arteries, and oxygenated blood returns via the umbilical vein — both of which cease function after birth and become ligaments.

frq 3: describe what the graph is illustrating in terms of blood velocity, pressure, and cross sectional area in each of the major types of blood vessels (label)

(labled on image)

how many capillary beds does a red blood cell pass through during one full circulation, and why?

• a red blood cell passes through two capillary beds during one full circulation

  • systemic capillary bed, where it delivers oxygen to body tissues

  • pulmonary capillary bed, where it picks up oxygen in the lungs

hypotension

low blood pressure, vessels dialate

how does overexcitement lead to hypertension

leads to higher rate, increased bloodflow and constricted blood vessels = increased blood pressure

excess salt in diet can increase blood pressure because..

blood vessels constrict, extra H2O moved into blood, increased blood volume

atheroscelerosis

accumulation of fatty deposits in veins

thrombus

stationary clot

embolus

moving clot

stroke

embolus that moves to a vessel in the brain and blocks it

heart attack

portion of heart dies due to lack of oxygen

jugular vein

major blood vessels in the neck that drain deoxygenated bloo dfrom the head/neck back into the heart

pulmonary circulation

Carries oxygenated blood from the left side of the heart to the body, delivers oxygen/nutrients, and returns deoxygenated blood to the right atrium.

systemric circulation

Carries oxygenated blood from the left side of the heart to the body, delivers oxygen/nutrients, and returns deoxygenated blood to the right atrium

describe how a tumour would form in the brain, and the route a cancerous cell would follow if it metastasized from the brain to the liver

• mutations in the dna cause cells in the brain to divide uncontrollably → these mutations can disable tumour suppressor genes/activate oncogenes, leading to rapid growth + formation of a mass.

• cancerous cells can enter the cerebral veins, draining into the internal jugular vein

  • travel through the superior vena cava → heart → pulmonary circulation. passes through the lungs → enters systemic circulation via the aorta

  • reaches the liver through the hepatic artery (a branch of the aorta), where they may form secondary tumours and spread to other organs

describe the process the body undergoes to destroy foreign invaders with specific reference to the structure/function of the lymphatic system

• The foreign substance (antigen) is carried in lymph fluid through lymphatic vessels.

• It reaches a lymph node, where immune cells like B-cells, T-cells, and macrophages are located.

• Helper T-cells activate B-cells, wh ich then produce antibodies specific to the antigen.

• Antibodies bind to the antigen, neutralizing it or causing agglutination (clumping), making it easier to destroy.

• Cytotoxic T-cells target and destroy infected cells directly.

• Macrophages or other phagocytes engulf and digest the tagged invaders.

• The lymphatic system helps transport antigens, activate immune cells, and filter out pathogens in the lymph nodes.

angina

radiating pain caused by blockage of coronary artery

process of angioplasty

invasive, very thin wire inserrted into blood vessel, small balloon at end inflated to break up blockage

varicose veins

visible, protruding veins below surface of skin, caused by "leaky" valves in veins

phlebitis

inflammation of a vein (usually in legs), can sometimes lead to thrombosis (blood clot) that can travel to other parts of the body

pulmonary embolism

blockage of main artery to lungs

heart transplants

results from congestive heart failure, completely remove old organ and replace with new organ from donor. use of medication to prevent heart rejection

arteries

blood vessels that bring oxygen rich blood to body parts, branch into smaller arterioles. carry blood away from heart (exception: pulmonary artery)

capillaries

the smallest blood vessels that exchange gases and nutrients at the cellular level. They are distributed among all body tissues, and link arteries and veins.

describe the pathway that leads away from capillaries

capillaries ⇒ venules ⇒ veins

veins

thin walled, elastic, valve-containing blood vessels that bring oxygen poor blood TO the heart (exception: pulmonary vein)

correct order of blood vessels

arteries, arterioles, capillaries, venules, veins

pulmonary arteries

bring oxygen low blood from heart to the lungs

coronary arteries

blood vessels on the surface of the heart muscle that supply oxygen-rich blood to the heart muscle (myocardium) istself. theyhelp remove waste, and if they are blocked it can result in heart attacks

pulmonary veins

bring oxygenated blood from lungs to the heart

pulmonary circuit

blood vessels taking blood to and from the heart, include the capillaries that nourish lung cells

systemic circuit

vessels that circulate blood to body tissues that aren't part of the pulmonary tissues

cardiac cycle

complete sequence of one heartbeat: atrial contraction, ventricular contraction, and relaxation

systole

heart muscle CONTRACTION

diastole

heart muscle RELAXATION

cause of first part of heartbeat

vibrations of the heart when atrioventricular (tricuspid and bicuspid ) valves close

second part of our heartbeat is caused by

vibration of the semilunar valves closing

starting at the right atrium, describe the flow of blood through the heart to the lungs and to the body

right atrium, travels through tricuspid valve, right ventricle, travles through the pulmonary semilunar valve, pulmonary artery, pulmonary veins, left atirum, travels through the bicuspid valve, left ventricle, aorta, dosral aorta

Right atrium

Upper right heart chamber that receives deoxygenated blood from the body.

movement through tricuspid valve

Blood flows from right atrium to right ventricle.

Right ventricle

Lower right heart chamber that pumps blood to the lungs.

the pulmonary semilunar valve

Blood exits right ventricle into the pulmonary artery.

Pulmonary artery

Carries deoxygenated blood from heart to lungs.

Pulmonary veins

Carry oxygenated blood from lungs to left atrium.

Left atrium

Upper left heart chamber that receives oxygenated blood from lungs.

the bicuspid valve

Blood flows from left atrium to left ventricle.

Left ventricle

Lower left heart chamber that pumps oxygenated blood to the body.

Aorta

Largest artery that carries oxygenated blood from heart to body.

Dorsal aorta

Continuation of the aorta running along the back, distributing blood to the lower body.

purpose of valves

to prevent backflow of blood from the ventricles back into the atria when the ventricles contract

Septum

muscle tissue dividing the left and right sides of the heart.

• interventricular septum is the part of the septum that separates the left and right ventricles (the lower chambers).

• There is also an interatrial septum, which separates the left and right atria (the upper chambers).

Superior vena cava

Brings deoxygenated blood from upper body to right atrium.

Inferior vena cava

Brings deoxygenated blood from lower body to right atrium.

Chordae tendonae

tendon-like "strings" that pull down valves to allow flow of blood through the heart

SA node

pacemaker of the heart, intiates heartbeat and sents out excitation pulses to cause atria to contact. found in upper dorsal wall of the right atrium

AV node

when impulse from the SA node reaches the AV node, it signals ventricles to contract through specialized fibers called Purkinje fibers; found at base of right atrium (near septum)

what happens if the SA node fails to work?

the heart still beats, but irregularly

EKG

a test that records the electrical activity of the heart over time. it has 3 waves: P (contraction of atria), QRS (contraction of ventricles), T (recovery of ventricles)

blood pressure

force of blood pushing against the inside wall of the arteries. decreases as it moves further from the heart

basic components of blood

plasma proteins, platelets, red blood cells, white blood cells

blood is composed of what two main groups

formed elements (solid portion of blood) and plasma (the liquid portion)

Plasma

The liquid portion of blood that carries water, nutrients, hormones, and waste; makes up about 55% of blood volume

Formed elements

The solid components of blood: red blood cells, white blood cells, and platelets.

plasma proteins

maintain osmotic pressure/pH - help clotting, produced in liver

platelets

responsible for clotting, made in red bone marrow

red blood cells

transport oxygen, made in red bone marrow

white blood cells

fight infection, made in red bone marrow

blood velocity

high in arteries, drops at capillaries (due to large area/volume), increases speed at veins

blood pressure across the body

highest in arteries, steady decline in capillaries and veins

why is cross sectional area highest in capillaries

Because there are millions of tiny capillaries, their combined area is much greater than that of arteries or veins.

Cross-sectional area

The total area through which blood flows in a group of vessels at a given level of circulation.

Chemical reactions involving blood clotting

Vessel injury signals platelets and tissue cells ⇒ tissue cells release prothrombin activators ⇒ convert prothrombin (from liver) into thrombin ⇒ thrombin converts fibrinogen into fibrin ⇒ fibrin forms clot at injury site. Calcium and vitamin K are essential for activating prothrombin and enabling clotting enzymes to function

blood proteins

carry hormones, vitamins, lipids in the blood, thickening blood and providing pressure

O₂ and CO₂ transport via hemoglobin

In lungs, hemoglobin binds oxygen to form oxyhemoglobin ⇒ delivers O₂ to tissues ⇒ in tissues, hemoglobin picks up CO₂ (as carbaminohemoglobin (some) or helps convert it to bicarbonate (most)) ⇒ transports CO₂ back to lungs for exhalation.

Hemoglobin

A protein in erythrocytes (red blood cells) that binds oxygen in the lungs and carries it to tissues; also helps transport carbon dioxide back to the lungs.

HDL cholesterol

"good" cholesterol, high density lipoprotein

LDL cholesterol

"bad" cholesterol, low density lipoprotein

components of the lymphatic system

lymphatic vessels, lymphoid organs, lymph nodes, spleen, thymus gland, red bone marrow

Lymphoid organs

Organs involved in immune defense: lymph nodes, spleen, thymus, and red bone marrow.

Lymph nodes

Small, bean-shaped structures that filter lymph and house immune cells to fight pathogens.

Spleen

Organ that filters blood, removes old red blood cells, and helps fight infection.

Thymus gland

Gland where T cells mature; active in childhood and shrinks with age.

Red bone marrow

Tissue inside bones where blood cells, including lymphocytes, are produced.

Lacteal

A lymph capillary in the small intestine that absorbs dietary fats.

Subclavian vein

Large vein under the collarbone where lymph reenters the bloodstream.

Lymphatic duct

Major vessel that drains lymph into the subclavian veins (e.g. thoracic duct).

Thoracic duct

The largest lymphatic duct; drains lymph from most of the body into the left subclavian vein.

Lymph vessels

General term for all vessels that carry lymph, including capillaries and ducts. they are structurally like veins, have valves

Lymphatic vessels

Thin-walled tubes that transport lymph from tissues back to the bloodstream.

flow of lymph fluid: right upper body

tissue fliod ⇒ lymphatic capillaries, lymphatic vessels, right lymphatic duct, right subclavian vein, superior vena cava

flow of lymph fluid: lower body and upper left

tissue fluid ⇒ lymphatic capillaries ⇒ lymphatic vessels ⇒ thoracic duct ⇒ left subclavian vein ⇒ superior vena cava

Antibodies

Proteins made by B cells (lymphocytes/white blood cells) that specifically bind to antigens to neutralize or mark them for destruction. There are specific antibodies for each antigen, able to recognize them because of receptor specificity.

How antibodies work

Bind to antigens

Immune response

Antigen detection triggers immune cells (B and T cells)

How does the immune system respond to an antigen using the lymphatic system?

1. Antigens enter lymph fluid → carried to lymph nodes

2. Helper T-cells activate B-cells and cytotoxic T-cells

3. B-cells produce specific antibodies → bind antigens → cause agglutination

4. T-cells destroy tagged pathogens (some by engulfing)

5. Memory cells remain → enable faster response if antigen returns

memory cells

long lived B/T cells that remember a specific antigen for faster immunity later

Antigens

Foreign molecules (like parts of viruses or bacteria) that trigger an immune response. they are glycoprotein chains within plasmamebrane of the foreign substance