The Human Circulatory System

What are the parts of the Circulatory system? What do they make up?

1. The Heart

2. Blood vessels

3. blood

They all make up the CARDIOVASCULAR SYSTEM

Functions of the Circulatory System?

1. Transport: Nutrients, waste, hormones, and blood cells

2. Protection: from blood loss and pathogens (disease)

3. Temp. Regulations: blood is make up of mostly water, has a moderating effect on the body

Blood Vessel types?

1. Arteries

2. Arterioles

3. Capillaries

4. Veins

5. Venules

How many layers do arterial walls have? What are they? (arteries)

They have 3 layers

1. Inner: made of endothelium

2. Middle: made of smooth muscle to regulate blood

3. Outer: connective tissue and elastic tissue for support

Arteries (info)

• takes blood away from heart

• The arterial wall needs to be highly elastic to dilate and contract.

• Function: circulate OXYGENATED BLOOD towards body tissue

• Exception: pulmonary arteries take DEOXYGENATED BLOOD to the lungs (artery rule)

• Aorta is the largest artery in the body

• Arteries DON’T have valves

Arterioles

• smaller arteries, lead to capillaries

• have the ability to undergo “vasoconstriction” and “vasodilation” like arteries

• vaso- means vessels

Capillaries

• most abundent

• joins arterioles and venules (smaller veins)

• the site of nutrient + waste exchange + gas exchange + delivery or secretion of hormones

• capillary is 1/10 the diameter of a human hair

• the wall of capillaries are one cell thick for materials to easily be exchanged

• capillaries are all around the body

Veins

• take blood in to heart

• veins + venules (smaller veins) take blood from capillary network (bed) to the heart

• Function: to carry DEOXYGENATED BLOOD from the capillary bed to the heart

• Exception: pulmonary veins carry oxygenated blood

• veins have 3 walls like arteries but thinner

• veins have valves. Valves prevent blood from moving backwards. Valves are found commonly in the body against gravity.

• veins use skeletal muscle contractions + valves to push blood back up to heart

Valves

• prevent blood from moving backwards

• valves are found more commonly in the body against gravity

Venules

• Function: to transport oxygenated poor blood from capillaries to veins

• Thinner structure and narrower diameter compared to veins

The heart (location and function)

• The heart is a cone-shaped muscular organ that is about the size of a fist

• It is located slightly left, between the L+R lungs and tilted so the apex (pointed part) is oriented left

FUNCTION:

1. pumping blood through body

2. Keeping oxygen rich and oxygen poor blood seperate

3. Ensuring that blood flows in one direction through body via pathways

The heart (structure)

THE HEART HAS 4 CHAMBERS:

2 ATRIA - the upper, thinner chambers

• the atria receives blood from the BODY (oxygen POOR) and LUNGS (oxygen RICH)

2 VENTRICLES - the lower, thick-walled chambers

• the hear lies within the pericardium - a thick membraneous sac that secretes lubracating fluid (like serosa)

• the muscular part of the heart that pumps blood is called the MYOCARDIUM. The layer is primarly composed of cardiac muscle (involuntary control like smooth muscles).

• the inner surface of the heart is known as the endocardium (similar to mucosa)

• the R. and L. side of the heart is separated by the septum

• the heart has 4 valves that direct blood and prevent back flow

• the 2 valves that separate the atria and ventricle is known as the ATRIOVENTRICULAR VALVE/AV VALVE. They are supported by CHORDAE TENDINAE, perevents inverting

• AV Valve on R. side is known as the tricuspid valve (3 flaps)

• AV Valve on L. side is known as the bisucpid valve (2 flaps)

• The other 2 valves are located between the ventricles and their attached vessel. They’re called SEMILUNAR VALVES.

• the pulmonary valve (R. semilunar) is between R.ventricle and pulmonary artery

• the aortic valve (L. semilunar) is between the L. ventricle and aorta

What vascular pathways does the heart use to send blood through?

there are 2 vascular pathways that the heart sends blood through:

• SYSTEMIC UNIT

• PULMONARY CIRCUIT

Gas Exchange

PULMONARY CIRCUIT transports O2 poor blood to the lungs:

• When the blood reaches the lungs, O2 and CO2 exchange by simple diffusion between the blood in the CAPILLARIES and the air in alveoli of the lungs by the action if inhalation and exhalation

SYSTEMIC CIRCUIT transports O2 rich blood from the L. ventricle of the heart to the body tissue

• capillary exchange of O2+CO2 occurs of the cell, Nutrients enter while waste exits

• O2 poor blood then returns to the heart into the right atrium

• the aorta and vena cava serve as major pathways for blood in systemic circuit.

• CORONARY CIRCULATION is a branch of the systemic circuit that provides O2 rich blood to the myocardium. Blockage of a coronary artery leads to a heart attack!

The Heart pt 2

• the right side of the heart receives blood from body (venous blood/O2 poor blood)

• both SUPERIOR+INFERIOR VENA CAVA brings that VENOUS blood into the RIGHT ATRIUM

• the R.A. sends the blood through the tricuspid valve and into the R. VENTRICLE

• R. VENTRICLE sends blood through pulmonary VALVE and into PULMONARY TRUNK

• PULMONARY TRUNK separates into the R+L PULMONARY ARTERY which goes to the lungs (gas exchange)

• CAPILLARIES in the lungs provide movement of CO2 out (exhalation) and O2 in (inhalation)

• the left side of the heart is reverse, O2 rich blood from the lungs is transported by the PULMONARY VEINS

• blood now flows through PULMONARY VEINS into L. ATRIUM and through the BICUSPID VALVE and into the L. VENTRICLE

• the L. VENTRICLE sends blood through the aortic valve to deliver O2 RICH blood to entire body

• the right side of the heart sends blood to lungs

• the left side of the heart sends blood to body

• the left ventricle is the strongest chamber as it has to pump blood against gravity to whole body