Topic 2- Organisation Flashcards
What does the circularatory system do?
Provides oxyen and nutrients to all cells in the body and removes waste products. The heart pumps blood in a double circularatory system!
Deoxygenated blood:
Blood flows into the right atrium, then the right ventricle, which pumps it to the lungs for gas exchange.
Oxygenated blood:
Flows into the left atrium, then into the left ventricle, ppumping blood around the body.
Structure of the heart:
- Muscular walls- strong heartbeat
- Muscular wall of left ventricle is thicker- blood is pumped around all the body, rather than just the lung
- 4 chambers- seperate the oxygenated blood from the deoxygenated blood
- Valves- prevent backflow of blood
- Coronary arteries cover heart- provides it’s own oxygenated blood supply
Process of blood flow:
- Blood flows into the right atrium through the vena cava and left atrium through the pulmonary vein
- Atria contract, forcing blood into the ventricles
- The ventricles then contract, pushing blood in the right ventriclle into the pulmonary atery to be taken to the lungs, and the left ventricle to the aorta to be taken around the body.
- As this happens, the valves close to prevent backflow.
Pacemaker:
A group of cells in the right atrium. They provide stimulation through electrical impulses, which pass as a wave across the heart muscle, causing it to contract. WIthout this, the heart would not be able to pump fast enough to deliver the required amount of oxygen to the whole body.
Arteries:
Arteries carry blood AWAY from the heart.
* Layers of muscle in the walls make them strong
* Elastic fibres allow themm to stretch
* This helps the vessels withstand high pressure created by the pumping of the heart
Veins:
Veins carry blood TOWARDS the heart.
* The lumen (tube that blood throws through) is wide to allow the low pressure blood to flow through
* They have valves to ensure that the blood flows in the direction
C
Capillaries:
Allow the blood to flow very close to cells to enable substances to move between them.
* One cell thick- creatig a short diffusion pathway.
* Permeable walls- so substances can move accross them.
Ventillation:
- The ribcage moves up and out and the diaphragm moves down causing the volume of the **chest to increase. **
- Increased volume results in lower pressure.
- Air is drawn into the chest as air moves from areas high pressure (the environment) to low pressure (the lungs).
- The opposite happens when exhaling.
Gas exchange:
- Upon inhalation, the alveoli fill with oxygen.
- The blood in the capillaries surrounding the alveoli is deoxygenated (it has come from the pulmonary vein). It has lots of carbon dioxide as this is a **product of respiration. **
- Oxygen diffuses down its concentration gradient into the capillary bloodstream, which has a low concentration of oxygen.
- Carbon dioxide diffuses down its concentration gradient from the blood to the alveoli
How are the alveoli adapted for efficient gas exchange?
● They are very small and arranged in clusters- creating a large surface area for diffusion to take place over
● The capillaries provide a large blood supply- maintaining the concentration gradient
● The walls of the alveoli are very thin- creating a short diffusion pathway
Blood:
Blood is made up of plasma, red blood cells, white blood cells and platelets.
Plasma:
The liquid that carries the components in the blood.
Red blood cells:
● They carry oxygen molecules from the lungs to all the cells in the body
● Their bioconcave disc shape provides a large surface area
● They have no nucleus allowing more room to carry oxygen
● They contain the red pigment haemoglobin, which binds to oxygen and forms oxyhaemoglobin
