The cardiovascular system is made up of.docx

The **cardiovascular system** is made up of: - **The blood vessels-** the tubes that carry the blood. - **The heart**- to pump the blood through the network of blood vessels - **The blood**- the fluid that is transported through the system. We will study each of the components and thei...

The **cardiovascular system** is made up of: - **The blood vessels-** the tubes that carry the blood. - **The heart**- to pump the blood through the network of blood vessels - **The blood**- the fluid that is transported through the system. We will study each of the components and their functions in turn. **[Blood]** The main blood components are the blood cells, platelets and the plasma. The components of the blood have two main functions, **TRANSPORT and DEFENCE AGAINST DISEASE.** **[The blood vessels]** 3 main types of blood vessel: - **Arteries** -- these carry blood **away** from the heart. **A** for artery **A** for away - **Veins** -- these carry blood back **to** the heart - **Capillaries** -- these tiny vessels link arteries to veins. [Diagram showing the relationship between the 3 blood vessels.] **[Arteries]** Arteries are adapted for carrying blood under high pressure **AWAY** from the heart towards the organs of the body. **[Cross section of an Artery]** Arteries The artery consist of a **small lumen** where the blood flows through under high pressure and three different tissue layers which consist of different types of tissue. +-----------------------+-----------------------+-----------------------+ | **Structure** | **Blood pressure** | **Adaptation** | +=======================+=======================+=======================+ | 1.**Thick wall** | **High (in pulses)** | - The **elastic | | consisting of: | | tissue** in the | | | | thick middle | | - An outer thin | | layer allows the | | layer od fibrous | | artery to | | tissue | | **stretch** as | | | | the blood | | - thick middle | | **pulses** out of | | layer of muscle | | the heart and | | and elastic | | through the | | tissue | | arteries. | | | | | | - thin inner | | - As the **elastic | | endothelial layer | | tissue recoils** | | of very flat | | between | | squamous | | heartbeats it | | epithelial cells | | helps **push | | | | blood** along the | | - | | arteries and | | | | **smooths blood | | 2\. **A narrow | | flow.** | | lumen** | | | | | | - The **muscle | | 3\. Usually an | | tissue** in the | | overall **rounded | | middle layer is | | shape** | | essentially a | | | | **supporting** | | | | layer- it | | | | provides | | | | **strength.** | +-----------------------+-----------------------+-----------------------+ **[Veins]** Veins are adapted to carry blood **TO** the heart under **low pressure.** Veins have a large lumen making it easier for a large volume of blood to flow back to the heart. +-----------------------+-----------------------+-----------------------+ | **Structure** | **Blood pressure** | **Adaptations** | +=======================+=======================+=======================+ | **1.Thin wall** | **Low** | - The **large | | | | lumen** **offers | | - an outer thin | | little | | layer of fibrous | | resistance** to | | tissue | | blood flow | | | | (essential due to | | - thin middle layer | | low blood | | containing some | | pressure in | | muscle and very | | veins) | | little elastic | | | | tissue | | - **Valves** | | | | prevent the | | - inner endothelial | | backflow of | | layer of squamous | | blood. | | epithelial cells | | | | | | - There is much | | **2. A large lumen** | | **less elastic | | | | tissue and muscle | | **3. Valves** at | | tissue** in the | | intervals along its | | walls (again due | | length | | to the low | | | | pressure and the | | **4. Irregular | | absence of a | | shape** when compared | | pulse in veins) | | with an artery | | | | | | - However, as in an | | | | artery, a vein | | | | has a thin outer | | | | protective | | | | fibrous layer and | | | | an internal | | | | endothelial layer | | | | of squamous | | | | cells. | +-----------------------+-----------------------+-----------------------+ Veins have **semi-lunar valves** along them to **prevent backflow** of blood (i.e. blood flow away from heart). Blood is squeezed along when skeletal muscles contract. http://3.bp.blogspot.com/\_FYzmMSSuvWc/TEF6HXh-24I/AAAAAAAAFco/BmkzCAHhmuI/s1600/venous\_valve2.jpg **[Capillaries]** Capillaries are adapted for exchange of substances between the blood and the cells. Vast networks of capillaries slow the blood allowing time for diffusion to occur.  +-----------------------+-----------------------+-----------------------+ | **Structure** | **Blood pressure** | **Adaptations** | +=======================+=======================+=======================+ | Microscopic vessel | **L*ow*** | - Its small size | | with a **one cell | | allows an | | thick wall**, | | **extensive | | consisting of | | network** of | | squamous endothelium. | | capillaries, | | | | providing a | | | | **large surface | | | | area** for the | | | | diffusion of | | | | material. | | | | | | | | - A capillary has a | | | | very thin wall | | | | (one cell thick) | | | | which allows | | | | exchange between | | | | the blood and the | | | | tissues | | | | | | | | - The capillary | | | | wall is permeable | | | | to respiratory | | | | gases, nutrients | | | | such as glucose, | | | | and waste | | | | including urea, | | | | but its not | | | | permeable to | | | | large proteins | | | | and red blood | | | | cells. | +-----------------------+-----------------------+-----------------------+ **[Comparison of blood vessels]**