B2__Organsiation

The Heart

Diagram Left/Right are flipped because its as if you are looking though at somebody else’s heart Most of the heart Is self explanatory or simply explained by the diagram so no extra info is needed

Blood

Blood is the transport medium of gas and nutrients it contains 4 major substances

Red Blood Cells

Transport oxygen after absorbing it from lungs. Their Adaptations are:

  • They contain haemoglobin - a red protein that combines with oxygen
  • They have no nucleus so they can contain more haemoglobin
  • They are small and flexible so that they can fit through narrow blood vessels
  • They have a biconcave shape (flattened disc shape) to maximise their surface area for oxygen absorption.

White Blood Cells

White blood cells defend the body against disease The majority of the white blood cells are a type of cell called phagocytes. More in Immune System

Platelets

They help to form scab and clot blood to prevent blood loss they do this by

  • Releasing chemicals to form a mesh
  • Sticking together to form clumps that get stuck in the mesh

Plasma

  • Transports carbon dioxide from respiring cells to the lungs
  • Transports digested food from the small intestine to respiring cells
  • Transports urea from the liver to the kidneys for excretion
  • Distributes heat all around the body
  • Transports Hormones from the glands where they are made to the target organs

Blood Vessels

There are 3 types of blood vessels: Arteries, Veins, Capillaries and they all have different functions and adaptations

Arteries

  • Carries blood (Usually oxygenated except from the pulmonary artery) AWAY from heart to places it’s needed in the body
  • Thick elastic and muscular walls
  • Narrow lumen
  • Contain blood under HIGH pressure

Veins

More or less the opposite of arteries

  • Carries blood (Usually de- oxygenated blood except from the pulmonary vein) INTO the heart.
  • Thin, less muscular walls
  • Wide lumen
  • Contain blood under LOW pressure
  • Has valves to prevent backflow of blood

Capillaries

Very different to veins and arteries. They are the Site of gas and nutrients (from the blood) exchange

  • Found near every living cell
  • Microscopic - walls are a single cell thick to allow easy diffusion into cells
  • Very low blood pressure

Table of Properties

InformationArteryVeinCapillary
Type of bloodOxygenatedDeoxygenatedBoth
DirectionAway from the heartTowards the heartFrom arteries to veins
PressureHighLowLow
Size of hole (lumen)SmallLargeVery small
Wall thicknessThickThinOne cell thick
ValvesNoYesNo

Coronary Heart Disease

This is a disease that is caused by blocked coronary arteries (arteries that supply blood to the muscle of the heart) usual blocked by Fatty Plaques containing cholesterol

Symptoms

If a coronary artery is blocked, the blood supply to part of the heart muscle is cut off. That part of the heart cannot continue to contract, causing a heart attack.

Treatments

TreatmentDescriptionAdvantagesDisadvantages
StatinsA daily medication to control blood cholesterol levelsDrugs reduce blood cholesterol levelsMay cause side effects
AngioplastySurgery to insert a small balloon into a blood vessel which is then inflated to remove a blockageImproved blood flow in coronary vessels preventing heart attackSometimes only a temporary measure
Lifestyle changesDiet and exercise, stopping smoking etcReduces risk of heart disease and reduces blood pressureA high level of willpower is required to maintain the changes