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Chapter 8: Transport in Humans (Cardiac cycle (The cycle starts when the…
Chapter 8: Transport in Humans
BLOOD
Plasma > Red Blood Cell > White Blood Cell > Platelets
WBC
Lymphocytes
:check: Large Rounded Nucleus
:check: Little Cytoplasm
:check: Produce Antibodies
Phagocytes
:check: Prevents harmful micro org.
(eg: poison as it can be neutralised)
Functions
:check: Digest food substances
:check: Hormones
:check: Excretory Products
:check: Heat
:check: Oxygen
Low in Oxygen : Blue or Purple
High in Oxygen : Bright Red
Blood Clotting prevents excessive blood loss & harmful micro org. from entering the blood vessel.
BLOOD VESSELS
Arteries
Carry blood
AWAY
from the heart
Thick, muscular & Elastic walls
Carry
OXYGENATED
blood with the exception of the pulmonary arteries.
Cappilaries
Microscopic vessels
One-cell thick wall
Exchange of substances to take place
Veins
Carry blood
TO
the heart
Blood pressure is much lower than arteries therefore blood flows more slowly and smoothly.
Assisted by semi-lunar valves which prevent blood from back flowing.
Carry deoxygenated blood with the exception of the pulmonary veins
Outside
blood vessel: High in CO2
Inside
blood vessel: Low in CO2
Heart
-Made up of cardiac muscle tissue
Four chambers are the right & left atria and ventricle
Right side pumps deoxygenated blood and the left side pumps oxygenated blood.
Cardiac cycle
The cycle starts when the whole heart is relaxed. The right atrium receives blood from the venae cavae and the left atrium receives blood from the pulmonary veins.
The atria then contract. The atrioventricular valves are already open and blood flows into the ventricles. Next, the ventricles contract and the atrioventricular valves close.
The pressure in the ventricles increases causing the semi-lunar valves in the pulmonary artery and aorta to open Blood flows into the aorta and pulmonary artery. Finally, the ventricles relax.
Coronary Heart Disease
Coronary heart disease occurs when the coronary arteries become blocked or narrowed. The heart muscles will no longer be able to receive sufficient oxygen and nutrients This can cause a heart attack.
A cause of coronary heart disease is
atherosclerosis
Factors that contribute to atherosclerosis include:
(a) High intake of cholesterol and saturated fats
(b) Stress
(c) Smoking
Preventive measures include:
(a) Healthy diet- low in cholesterol and saturated fats
(b) Not smoking nicotine increases blood pressure
(c) Exercising lowers stress and strengthens the heart