Lesson 5: The heart

We learned about the heart during the first half of the lesson. During the second half we took a test to see if we are on track and able to continue. I hope I did well, but I have sinced realised that I crossed out a correct answer and replaced it with an incorrect one. That's worse than being straight out wrong. :-(
When I have access to a scanner, I shall put some of my diagrams on the board. I may be able to tell what they are meant to represent. I may not.


The heart

• Pumps blood thru the body
• Blood flows from the heart to the organs thru arteries and returns thru veins
• In the organs, blood flows thru capilaries (veins and arteries are too think to allow anything thru)
• Substances needed by cells in the body tissues pass out of the blood, and substances pruduced by the cells pass into the blood thru the walls of the capillaries

There are two separate circulation systems, one to the lungs and one to all the other organs of the body. Lungs are the start and end of the circulation, the heart is the booster in the circuit.


Out of the heart = Arteries
Into the hear = Veins


Blood plasma transports

• Carbon dioxide from the organs to the lungs
• soluble products of digestion from the small intestine to other organs

Blood
Red blood cells transport oxygen from the lungs to the organs.
Red blood cells have no nucleus, they are packed with a red pigment called Haemoglobin.
In the lungs, haemoglobin combines with oxygen to form Oxyhaemoglobin
In other organs it splits into haemoglobin and oxygen


Present in blood are:

• Red blood cells
• White blood cells
• Plasma
• Platelets

Plasma contains
Nutrients
hormones
water
carbon dioxide
urea


Red blood cells carry haemo globin, which combines with oxygen in the lungs to form oxyhaemoglobin. Cells of all the organs want this.