Circulatory and Respiratory Systems

Bio 250

The Circulatory System• The Circulatory system consists of two

systems:– Cardiovascular system – composed of the

blood, heart and blood vessels– Lymphatic system – consists of the lymph,

lymph nodes and lymph vessels• Lymph – excess fluid in the tissues.• Lymph vessels – collect the lymph and transport it

to lymph nodes and back into the blood stream• Lymph nodes – filter the lymph fluid. • There is no pumping organ which circulates lymph,

the fluid travels through the lymph vessels due to muscle contractions.

The Cardiovascular System• The main organ of the cardiovascular system is

the heart. The heart is the driving force which circulates the blood through all the tissues.– The heart is surrounded by the pericardium – a tough

sac which protects the heart and secretes a fluid to reduce friction caused by the heart’s beating.

– The heart is divided into four chambers:• Two upper chambers called atria (atrium is

singular) receive blood and pass it to the ventricles.

• Two lower chambers called ventricles receive blood from the atria and pump it to places in the body.

Heart Rate• Take your resting pulse for 1 min. What is

it?• Calculate 220- your age. This is your max

heart rate. • You should generally workout between 50

and 85% of max heart rate. • Calculate %70 of your max heart rate. • Perform 20 jumping jacks. Take your

pulse for one minute. What is it? • Were you above or below 70% of your

max heart rate?

Right Left

Right Atrium - Receives blood from the superior and inferior vena cava and passes it to the right ventricle.

Superior Vena Cava – Receives deoxygenated blood from the upper part of the body.

Inferior Vena Cava – Receives deoxygenated blood from the lower part of the body.

Right Ventricle – Receives blood from the right atrium and pumps it through the pulmonary arteries to the lungs.

Pulmondary Trunk - Leads out of the right ventricle and splits into the right and left pulmonary arteries.

Left Pulmonary Artery – Leads to the left lung.

Right Pulmonary Artery – Leads to the right lung.

In the lungs, the blood picks up oxygen andbecomes oxygenated.

We still need to deliver that oxygen to the rest of the body!

Right Left

Blood returns to the heart through the right and left pulmonary veins.

Left Atrium – Receives blood from the pulmonary veins and passes it to the left ventricle.

Left Ventricle – Receives blood from the left atrium and pumps it through the aorta to the rest of the body.

Aortic Arch – Delivers blood to the body.

Pulmonary vs. Systemic Circulation• Circulation in the human body is often

referred to as a double-circuit – meaning it passes through the heart twice on its way back to the body.– Pulmonary Circulation – Is the flow of blood

between the heart and the lungs.– Systemic Circulation – Is the flow of blood

between the heart and the body.

The Blood Vessels• The human circulatory system is said to be

a closed system because the blood never leaves blood vessels.

• There are 3 main types of blood vessels:– Arteries– Capillaries– Veins

Blood Vessels cont.• Arteries - Carry blood away from the heart.

– Have a thicker layer of muscle than veins.– Carry blood under high pressure (the force of the

heart pumping).• Capillaries – Very thin vessels through which

gas exchange (oxygen and carbon dioxide) occurs. – Thin so diffusion can occur quickly.– Only one cell at a time can pass through the

capillaries.• Veins – Carry blood back to the heart under low

pressure.– Have valves to stop blood from flowing backwards.– Thinner layer of muscle than arteries because blood

isn’t flowing under high pressure.

Components of Blood• There are 4 main components of blood:

– Plasma – The liquid portion of blood. • Slightly yellow in color• About 90% water• Nutrients are dissolved in the plasma and

delivered to cells all over the body.– Red Blood Cells (RBC) – Make hemoglobin

which transports oxygen.• Also called erythrocytes.• Formed in your bone marrow.• Do not have a nucleus as mature cells – they

cannot divide/reproduce! Usually only live about 120 days.

Components of blood cont.– White Blood Cells (WBC) – Help defend the

body against disease.• Also called leukocytes.• Larger than RBC, much less plentiful.• Squeeze through the walls of capillaries to reach

the site of infection.

– Platelets – Fragments of very large cells which help form blood clots.• The blood contains a lot of platelets, a cubic

micrometer may contain up to half a million platelets!

Blood Types• Each person has a blood type. This blood

type is determined by the antigen present on the surface of the RBC.– An antigen is a substance which enables the

body to recognize itself from foreign substances such as pathogens.

– What happens if someone is given the wrong kind of blood?• The antigens on the RBC cause an immune

response and the immune system causes the blood to clot!

Blood types continued• The A-B-O System

– A system of classifying blood types based upon the antigens on the surface of the cells.

In addition to the A and B antigens, scientists have discovered another antigen present in 85% of the human population in the USA.This antigen is called the Rh Factor – it is named after the rhesus monkey in which it was first discovered.The Rh factor is where you get the + or – in your blood type.

The Respiratory SystemAir enters the body through the mouth or nose. Nose hairs in the nose will filter particles out of the air.

Air then travels through the pharynx which contains a passageway for both food and air.

Epiglottis – A flap of tissue which folds down and covers the air passageway when you swallow food.

Trachea – During breathing, a passageway for air. Has cartilage rings to make it rigid and keep airway open.

Larynx – or voicebox. As air travels over two ligaments here, it produces sound.

The trachea branches into two bronchi (singular, bronchus) which each lead to a lung.

The Respiratory System cont.The bronchi branch into bronchioles, which eventually end in alveoli.

Alveoli – grapelike clusters of tiny air sacs which are surrounded by capillaries.Oxygen from inhaled air enters the blood stream through diffusion through the alveoli and capillaries.

The Mechanism of Breathing• Breathing is the process of moving air into and

out of the lungs.• Inspiration - Taking air into the lungs.

– Air pressure inside and outside of your body must be equal.

– When you inhale, your diaphragm drops and your rib cage expands – causing your chest cavity to become larger.• You have the same amount of air in a larger space so the air

pressure drops.

– Air flows into your lungs to equalize the air pressure between the inside of your body and the outside.

The mechanism of breathing cont.• Expiration – Releasing air from your body.

– The diaphragm relaxes and moves upward and the rib cage returns to its original size.

– This creates a smaller space with the same amount of air in it as before which raises the air pressure.

– Air moves out of the body to equalize the air pressure inside and outside of the body.