B4 Blood Vessels And The Heart Flashcards
What are the main components in blood
Plasma
Red blood cells
White blood cells
Platelets
Function of red blood cell
Carries oxygen and delivers it throughout our body
How red blood cells adapted to their function
They are small and flexible so they can fit through narrow vessels
Why do red blood cells need large surface area
For absorbing oxygen
Why does it help if blood cells don’t have nucleus
More room to carry oxygen
What is the structure of red blood cells?
Small
Disc-shaped
No nucleus
Function of white blood cell
Helps the body fight infection and other diseases
What is the structure of white blood cells?
They have a nucelus
Bigger than red blood cells
No definite shape
How white blood cells are adapted to their function
Can change shape to squeeze out of blood vessels
What can white blood cells produce
Antibodies and antitoxins
Name the 2 types of white blood cell and explain how they fight disease
Phagocytes - engulf (‘eat’) pathogens
Lymphocytes - create antibodies which destroy pathogens
What are the three main types of blood vessels
Arteries, veins, capillaries
Arteries
Carries blood pumped away from the heart
Veins
Returns blood to the heart
Capillaries
Allow fast exchange/diffusion of substances
Structure of an artery
Thick collagen, elastin & muscle wall
Narrow lumen
How does capillaries walls being 1 cell thick increase rate of diffusion
Decreases distance over which diffusion occurs
Why are artery walls thick
Have to withstand high blood pressure from the heart
Structure of vein
Thin muscle & elasin wall
Wide lumen
Have valves
Why do veins need bigger lumen then arteries
To help blood flow
Why do thick layers of muscle and elastic fibres help the arteries
Makes them strong and allows them to stretch and spring back
Why don’t veins need thick walls like arteries
Veins has lower blood pressure
Why do veins have valves
To help keep the blood flowing in the right direction
Structure of capillary
Very small blood vessel with thin-walled vessels composed of a single endothelial layer