The Transport SystemTopic 6.2

Transport Song

• http://www.youtube.com/watch?v=P_d0ykpzQgY

Transport

• Every minute or two, one red blood cell makes a complete circuit through the transport system.

The Heart’s Job

• The heart’s job is to collect blood in it’s atriums, pump the blood to the ventricles, then from the ventricles pump it to the pulmonary or systemic circuits.

• Along the way, it must open or close its valves.

VAlves• Right and left

atrioventricular valve between atrium and ventricle

• Right and left semilunar valve upon exiting each ventricle.

• Valves prevent backflow of blood into the wrong chamber.

http://www.youtube.com/watch?v=-fVDGu82FeQ

A RBC Journey

• A RBC first arrives through the vena cava at the right atrium, where it must wait for others to arrive.

• Then the atrium contracts and it gets pushed through the right atrioventricular valve into the right ventricle.

A RBC Journey

• Finally the right ventricle contracts and it is pushed passed the semilunar valve into the pulmonary artery.

Destination:Gas Exchange

• The pulmonary artery connects it to a lung.

• There it gets rid of his CO2 and collects fresh O2

• Afterwards, it heads back to the heart via a pulmonary vein

A RBC Journey

• It is dropped off in the left atrium, and again has to wait.

• Finally it is pushed through the open atrioventricular valve into the left ventricle.

Heart Animations

• http://www.kscience.co.uk/animations/heart.swf

• http://library.med.utah.edu/kw/pharm/hyper_heart1.html

• http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

Control of the heart• Most of the heart is made of cardiac muscle.

• Myogenic muscle contraction: Cardiac muscle contracts and relaxes without the control of the nervous system.

• Myogenic activity is controlled by the sinoatrial (SA) node.

Sinoatrial Node

• Known as the “pacemaker” of the heart

• This is a mass of tissue on the right atrium that sends out an “electrical” signal telling the atrium to contract

• It also sends a signal to the atrioventricular (AV) node

• The AV node delays 0.1 seconds, then signals for the ventricles to contract

Watch it work!

• http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_electrical.html

Heart Rate (pulse)

• “Resting heart rate” = approx 60 – 100 beats per minute.

• Pulse is lower for well trained athletes

• If your heart beats 72 times per minute, your SA node sends a signal about every 0.8 seconds

Listening to Your Heartbeat

• Use the stethoscope, listen to your heartbeat several times. The “lub-dub” sound comes from the closing of the heart valves.

• “Lub” = closing of atrioventricular valves

• “Dub” closing of semilunar valves

Check your pulse

• Hold your first and second fingers (not your thumb) under your jaw and once you can feel your pulse, start timing for 60 seconds, counting how many times your heart beats.

Increasing Activity

• Why might you need to raise your heart rate?

• The medulla (in your brainstem) sends a signal through the cardiac nerve to the SA node to increase the heart rate as needed.

• This doesn’t change HOW the heart beats, rather, it changes when.

• After exercise, the medulla sends a signal through the vagus nerve, which tells the SA node to take control again.

• Adrenaline hormone also tells the SA node to signal more quickly

The Systemic Circuit

• After leaving the aorta, RBCs make a path through the systemic circuit, delivering O2 to the rest of the body.

RBC’s Systemic Circuit

• Blood goes through:

• A large artery

• Smaller artery branches

• An arteriole (smallest artery)

• A capillary bed

• A venule (smallest vein)

• Larger veins

• A large vein taking the blood back to the heart

Arteries

• Arteries always takes blood away from the heart before it reaches a capillary.

• Thick, smooth, and their diameter can be controlled (this is how blood pressure changes)

• Blood is at a high pressure since it is being pumped by the heart

• They become smaller until they become arterioles, then blood reaches a capillary.

Coronary Artery

• The coronary artery branches from the aorta to the heart itself, supplying cardiac muscle with oxygen & nutrients.

• When it is blocked with plaque, heart attacks occur.

Capillary• A capillary is so small that only ONE blood cell

can fit through at a time.

• Their walls are thin – only one cell thick.

• This is where all exchanges take place:• Gas (O2, CO2)

• Nutrients (often in the villi)

• Blood loses its pressure since it has to squeeze through one at a time.

Vein• Veins always takes blood towards the

heart after it has been through a capillary.

• Thin walled since the blood is at a low pressure.

• Veins have internal valves to help prevent backflow as blood must often move against gravity.

Varicose Veins

Comparison Chart

Artery Capillary Vein

Thick walled Wall is 1 cell thick

Thin walled

Narrow lumen (inside channel)

Lumen allows only one cell through

Wide lumen

NO exchanges

ALL exchanges occur

NO exchange

No internal valves

No internal valves

Have internal valves

Internal pressure high

Internal pressure low

Internal pressure low

BLOOD Components

• Plasma: liquid portion of blood• CO2 is dissolved in

the plasma

• Erythrocytes: Red blood cells (carry O2)

BLOOD Components

• Leucocytes: White blood cells (phagocytes & lymphocytes)

• Platelets: Cell fragments that are involved in blood clotting

Blood TransportWhat is

Transported

Details

Nutrients Glucose, amino acids, etc. (NOT Lipids – these are transported by lymph)

Oxygen Reactant needed for aerobic cell respiration

Carbon Dioxide

Waste product of aerobic cell respiration

Hormones Transported from the gland that secreted them to the target cell where they signal something to change

Antibodies Proteins involved in immunity (disease prevention & control)

Urea Nitrogenous waste (filtered by kidneys and excreted in urine)

Heat Skin arterioles change diameter in order to gain or lose heat

Blood Transport

2.2.A3 Methods of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.