The Cardiovascular System

My heart will stop

What is the cardiovascular system?

• Includes the heart and the blood vessels

• It brings nutrients to the cells and helps get rid of wastes

• Blood is refreshed in the lung, kidneys, intestine and liver.

• Lymphatic vessels help this system by collecting excess fluid surrounding tissues, and returning it to the cardiovascular system

Functions of the CVS

• Generate blood pressure -Heart

• Transport blood - Heat, Hormones, and electrolytes

• Exchange of nutrients and wastes at the capillaries

• Regulate blood flow as needed

Systolic pressure and diastolic pressure

• Systolic pressure (top number)- Measure the pressure in your ateries when your heart beats and contracts

• Dystolic pressure (bottom number)- Measures the pressures in your ateries when you heart rests between beats

What is the function of blood pressure?

• To assist in the blood flow

• The higher the blood pressure, the more blood flow you have

The average person had 5 L of blood, what happens when that blood is lost

Blood pressure decreases

What is the main pathway of blood in the body?

Heart → arteries → aterioles→ capillaries → venules → veins → back to the heart

Lymphatic Vessels

Branch throughout the body and help this system by collecting excess fluid, waste, and immune cells from surrounding tissues and returning it to the cardiovascular system

Arteries

• Carry blood away from the heart, to the tissues, and their walls have three layers

• Arteries branch out to form arterioles

• Tunica Externa - Thick inner epithelium

• Tunica Media - Thick smooth muscle layer

• Tunica Interna - Outer connective tissue

Arterioles

• Are small arteries that regulate blood pressure

• They branch out

• They regulate the blood pressure and control how much blood is supplied to any organ

Capillaries

• Microscopic vessels between aterioles and venules and connect them together

• Made of one layer of epithial tissue

• Form capillarie beds of vessels where exchange with body cells occurs

• Combined large surface area

Veins

• Branches of venules come to form veins

• Carry blood away from the heart

• The lumin is much larger

• Veins that carry blood against gravity have valves to keep blood flowing towards the heart

• Ensure the blood only flows one way

• Most veins carry deoxygenated blood

• Have a much thinner smooth muscle layer

• Have valves

Valve Functions

• Valves can open and close, and are present to ensure the blood only flows one way

Venules

• Venules are small veins that receive blood from the capallaries

Anatomy of the Heart

• Large, muscular organ consisting of mostly cardiac tissue and the myocardium

• Surrounded by a sac called the pericardium

• Consists of 2 sides, right and left, seperated by a septum

• Consists of 4 chambers - 2 atria and 2 ventricles

• 2 sets of valves - semilunar valves and atrioventricular valves (AV)

• Valves produce the lub, dub sounds of the heartbeat

Blood vessels gather and form a circuit called

Coronary circuit

Aorta

• The main largest artery in the human body

• Aortic root - The base attached to the left ventricle of the heart, housing the aortic valve and cornory artery openings.

• Ascending arorta - The segment curving upward from the heart

• Aortic Arch - The cane-like bend at the top that branches into vessels supplying the head, neck, and arms

Blood vessels that bring blood to the heart

• Superior Vena Cava - Brings oxygen-poor blood from the the upper body, head, neck, arms, and chest to the heart

• Inferior Vena Cava - Brings oxygen-poor blood from the lower body, trunk, and legs, to the heart

• Pulmonary veins - Bring oxygen-rich blood from your lungs into your left atrium

Pulmonary Arteries

• Brings blood from the heart, into your lungs

• The only artery that carries deoxygenated blood

Pulmonary veins

• Bring oxygenated blood from the lungs into the heart

Internal Anatomy of the Heart

• Right Atrium - Receives deoxygenated blood, and then goes through the atrioventricular (tricuspid) valve into the right ventricle

• Left Atrium - Recieves oxygenated blood, and then atrioventricular (bicuspid) valve and then into the left ventricle

• Both recieve blood from the pulmonary veins

• When the ventricles contract, that is when the valves close

Pulmonary Trunk

• From the left ventricle goes into the pulmonary trunk, into the semilunar valves, from there the blood is distributed into through the pulmonary veins

How does blood flow through the heart?

• Inferior and superior vena cava (1) dump blood into the right atrium (2)

• Right ventricle (3)

• 2 pulmonary arteries (4) that leads to lungs (5) where blood becomes oxygenated

• pulmonary veins (6) bring blood from the lungs to the left atrium (7)

• Left ventricle (8) is large and muscular to pump blood into the aorta (9) and to the rest of the body (10)

• Eventually blood will be pumped back to each vena cava (1)

Contraction and Relaxation

• Together this makes a cardiac cycle

• Can also be known as Systole, and diastole

Papillary muscles and chordae tendineae

• Papillary muscles - Specialized cone shaped muscles inside the ventricles of the heart that anchor the antrioventricular valves to prevent blood from flowing backwards

• Chordae tendineae - Commonly known as the heartstrings are strong chords of connective tissue located inside the ventricles

The left ventricle is much more —— than the right ventricle because it must pump blood throughout the entire body

muscular

Vein and Arteries

Veins - Have a thinner wall and a larger center to contain more blood

Arteries - Are more muscular than veins to withstand the pressure exerted on them and carry blood toward the heart

How does the heartbeat occur?

• During systole the atria contract together followed by the ventricles contracting together.

• This is followed by diastole, a rest phase when the chambers relax.

• The cardiac cycle, or heartbeat, occur 70/times a minute on average.

Internal Control

• The SA node in the right atrium initiates the heartbeat and causes the atrium to contract, artifical peacemakers

• The impulse reaches the AV node, also in the right atrium, to send a signal down the AV bundle and Purkinje fibers that causes ventricular contraction.

• These impulses travel between gap junctions at intercalated disks

How is heartbeat controlled?

External Control

• Heartbeat is controlled by a cardiac center in the brains and hormones such as epinephrine and norepinephrine

• The brain can only speed up the heart rate

Depolarization

• The electrical activation of heart muscle cells that causes them to contract and pump blood

Repolarization

• Repolarization is the biological process where a cell's membrane potential returns to a negative resting state after a depolarization event

What is blood pressure

• It is the pressure against a blood vessel wall, usually measured in an artery of an arm

• The highest pressure called the systolic pressure, is during blood ejection from the heart

• The lowest pressure, the diastolic pressure, occurs when the ventricles relax.

• Average blood pressure is recorded at about 120/80 mmHg

• This is controlled by the aterioles

What is important about blood flow

• Blood flow is under the highest blood pressure in the arteries but remember the thick, muscular walls.

• Blood flow is slower in the capillaries which is important to allow time for exchange between the cells

• Blood pressure is minimal in the veins and venules but blood flow increases

If blood pressure is so low in the veins, why does the blood flow increase?

• They have help.

• 1. Skeletal muscle contraction

• 2. Breathing

• 3. Valves