Cardiovascular System

pe test 2

functions of blood

-transport

-regulation

-defence

-maintainence

-restriction

-stabilisation

components of blood

cellular (RBCs, WBCs, platelets) and fluid (plasma)

What does blood transport?

Gases, nutrients, hormones, and waste.

How does blood help with pH?

It regulates pH by absorbing acids like lactic acid.

How does blood prevent fluid loss?

Through clotting at injury sites.

How does blood defend the body?

WBCs fight toxins and pathogens.

How does blood control body temperature?

It absorbs and distributes heat from muscles.

What helps maintain blood volume?

Plasma proteins like albumin.

What shape are RBCs and why?

Biconcave discs – increases surface area.

Do RBCs use oxygen?

No, they have no mitochondria.

What do RBCs contain?

Haemoglobin for oxygen transport.

What helps RBCs fit in small vessels?

Their flexible shape.

Where are RBCs made?

In red bone marrow.

What triggers RBC production?

Low oxygen (hypoxia).

What hormone increases RBCs?

Erythropoietin (EPO) from kidneys.

What is haemoglobin?

A red protein in RBCs that carries oxygen.

How many O₂ can one Hb carry?

Four oxygen molecules.

How much Hb in one RBC?

280 million Hb molecules (can carry ~1 billion O₂).

What are blood types based on?

Surface antigens A, B, and Rh.

What happens in a wrong transfusion?

Immune system attacks the blood – clumping and rupture.

What is agglutination?

Antibodies clump foreign RBCs.

Why is blood typing done?

To prevent transfusion reactions.

What is haemostasis?

The process of stopping bleeding.

What’s the first phase of stopping bleeding?

Vascular phase – blood vessel spasms to reduce flow.

What’s the second phase of stopping bleeding?

Platelet phase – platelets stick and form a plug.

What’s the third phase of stopping bleeding?

Coagulation – fibrin forms a clot to stop bleeding.

What happens after clot forms?

Clot retraction pulls vessel edges together and heals.

What does the cardiovascular system include?

The heart (cardio) and blood vessels (vascular).

What do arteries and arterioles do?

Carry blood away from the heart.

What do veins and venules do?

Carry blood to the heart.

What do capillaries do?

Exchange O₂, CO₂, and nutrients.

What are the two circulations?

Pulmonary (lungs) and systemic (rest of the body).

Where is your heart located?

Between lungs, behind left of sternum.

How big is the heart?

About the size of a fist, weighs 250–350g.

How many times does the heart beat daily?

Around 100,000 times, pumping 8L of blood.

What covers the heart?

Parietal pericardium – double sac with fluid.

What are the 3 heart wall layers?

Epicardium (outer), myocardium (muscle), endocardium (inner lining).

How many heart chambers are there?

4 – 2 atria (top), 2 ventricles (bottom).

What are the AV valves?

Tricuspid (right), bicuspid/mitral (left).

What are the SL valves?

Pulmonary (to lungs) and aortic (to body).

What supplies the heart muscle with blood?

Coronary arteries (left and right).

What do cardiac veins do?

Drain blood into the right atrium.

What causes CAD?

Plaque (cholesterol) buildup in arteries.

What can CAD lead to?

Narrowed arteries, chest pain, and heart attacks (myocardial infarction).

what does CAD stand for

coronary artery disease

What is systole?

Heart contraction (blood pumped out).

What is diastole?

Heart relaxation (chambers refill).

What creates a pulse?

Each heartbeat moves blood through arteries.

What are the 2 cardiac cell types?

Conducting cells (1%) and contractile cells (99%).

What do conducting cells do?

Start and spread electrical signals.

What do contractile cells do?

Contract and pump blood.

Where does each heartbeat start?

In the SA node (pacemaker).

What’s the order of the signal?

SA node → AV node → AV bundle → bundle branches → Purkinje fibres.

What do intercalated discs do?

Help cells contract together by spreading signals.

What does the P wave show?

Atrial depolarisation (atria contract).

What does the QRS complex show?

Ventricular depolarisation (ventricles contract).

What does the T wave show?

Ventricular repolarisation (relaxation).

What are the 4 phases of the cardiac cycle?

Atrial systole/diastole, ventricular systole/diastole.

What happens during atrial systole?

Atria "top up" ventricles with blood.

What happens during ventricular systole?

Ventricles contract and eject blood.

What happens during ventricular diastole?

Ventricles relax and fill passively.

What causes the “lubb” (S1) sound?

AV valves closing.

What causes the “dubb” (S2) sound?

Semilunar valves closing.

What do S3 and S4 sounds mean if heard?

Possible heart disease.

What is cardiac output?

CO = HR × SV; blood pumped per minute.

What’s a normal CO?

~5.25 L/min at rest.

What’s tachycardia?

HR > 100 bpm. (fast heart rate)

What’s bradycardia?

HR < 60 bpm. (slow heart rate)

What does the sympathetic system do?

Speeds up HR → increases CO.

What does the parasympathetic system do?

Slows down HR → lowers CO.

What hormones increase HR?

Adrenaline, noradrenaline, T3.

What do baroreceptors do?

Detect BP changes and adjust CO.

What do chemoreceptors detect?

CO₂, O₂, and pH changes.

What are the three main types of blood vessels?

Arteries (away from heart), Capillaries (link arteries and veins), Veins (to heart)

How does the structure of blood vessels relate to their function?

It varies based on the function and pressure they withstand.

What is the path of blood flow in the systemic circuit?

Left heart → arteries → arterioles → capillaries → venules → veins → right heart → lungs → left heart

What are the three layers of arteries and veins?

Tunica externa, Tunica media (smooth muscle), Tunica intima (endothelium)

How do arteries and veins compare?

Arteries have thicker walls, elastic fibres, tolerate pressure; veins have valves, thinner walls.

What is the function of arterioles and venules?

Arterioles regulate BP via smooth muscle; venules connect capillaries to veins.

What is the structure and function of capillaries?

One cell layer thick; allow 2-way exchange of O2, nutrients, CO2, waste.

What are the two types of capillaries?

Continuous (tight diffusion), Fenestrated (pores, faster/larger exchange)

What is blood pressure (BP)?

Pressure blood exerts on arterial walls; necessary for adequate perfusion.

What is systolic and diastolic pressure?

Systolic: heart contracts (120 mmHg); Diastolic: heart relaxes (80 mmHg)

What is pulse pressure?

Systolic - Diastolic pressure. E.g. 120 - 80 = 40 mmHg

What does a pulse pressure >60 mmHg indicate?

Increased risk of cardiovascular disease

What is the blood pressure gradient?

Blood flows from high → low pressure; drives circulation

What is the typical pressure drop from venules to RA when lying down?

16 mmHg (venule 18 → RA 2)

What aids venous return to the heart?

1) Skeletal muscle pump; 2) Respiratory pump

What is the equation for blood pressure?

BP = Cardiac Output (CO) × Total Peripheral Resistance (TPR)

What determines cardiac output (CO)?

CO = Heart Rate (HR) × Stroke Volume (SV)

What increases stroke volume?

Increased venous return, sympathetic activity, vasoconstriction, muscle and respiratory pumps

What determines resistance (TPR)?

Arteriolar radius, blood viscosity, vessel length, turbulence

What is the main factor affecting resistance?

Arteriolar radius (affected by sympathetic activity and hormones like angiotensin II)

What are the short-term BP regulation mechanisms?

Autoregulation, Neural (baroreceptors, chemoreceptors), Endocrine (adrenaline, NA)

What is autoregulation?

Local response in tissues via pre-capillary sphincters to adjust blood flow

What is the role of the CV centre in neural regulation?

In medulla; includes cardiac and vasomotor centres to adjust HR, SV, and resistance

What do baroreceptors detect and where?

Blood pressure changes; located in carotid sinus and aortic arch

How do baroreceptors restore homeostasis?

Negative feedback loop alters CO and resistance quickly

What do chemoreceptors detect?

High CO2, low O2, low pH in blood and CSF

Where are chemoreceptors located?

Carotid bodies and aortic bodies