Bio 7 - The Circulatory System Flashcards
Is the mammalian Circulatory System Open or Closed ?
Closed
Is the Mammalian Lymphatic system Open or Closed ?
Open
Name five transport functions of the circulatory system
- Hormones from exocrine glands to tissues
- Molecules and Cells for the immune system
- Nutrients from the digestive tract to the liver
- Oxygen from the respiratory system to the cells
- Waste from body cells to the respiratory and excretory systems
Name two functions of the blood in relation to Thermoregulation ?
Distributing heat from Skeletal muscles and other active organs to the rest of the body
Blood is directed towards or away from the skin, depending on whether the body wants to release or conserve heat
Describe the path of deoxygenated blood through the systemic circulation
Deoxygenated blood returns to the heart from all body tissues except the lungs.
Blood enters the right atrium through large veins (Venae Cavae).
Blood is then pumped into the right ventricle via the tricuspid valve.
Blood then enters the Pulmonary circulation through the Pulmonary (Semi-Lunar) valves and Arteries.
Describe the Pulmonary Circulation from the heart
Blood is pumped to the lungs from the right ventricle via the semi-lunar valves and Pulmonary arteries.
The blood loses CO2 and is oxygenated in the lungs and returns through pulmonary veins to the left atrium.
Blood is then pumped through the Mitral (bicuspid) valve to the left (largest) ventricle and into the systemic circulation via the aortic valve and aorta.
Which is the largest Ventricle ? Why ?
The left ventricle because greater pressure is required to pump blood all around the body than to the lungs.
Describe the five different types of blood vessel
Arteries Arterioles Capillaries Venules Veins
Describe the composition of a blood vessel wall
Arteries tend to have thick, smooth, muscular walls as they need to withstand increased pressure.
Veins have thinner walls as they carry blood at lower pressure.
Outer- Adventitia
Middle - Media (muscle)
Inner - Intima
Explain how newly deoxygenated blood enters the right atrium
Deoxygenated blood enters very small Veins (Venules), then flows into larger and larger veins until it enter the Venae Cavae and into the right atrium.
What is the function of the Superior and Inferior Venae Cavae ?
The Superior Venae Cavae drains blood from the Upper body, the inferior from the Lower body.
Explain the muscle pump
Vein walls are thin and floppy, therefore they are often located in or near muscles.
E.g. The movement of the leg squeezes the veins, which pushes the blood through 1-way bicuspid valves towards the heart.
Explain the function of the Coronary Arteries ?
Coronary Arteries branch off the Aorta in order to supply the heart muscle
Explain Systolic and Diastolic blood pressure
Blood pressure is the force exerted by the blood against the inner walls of the vessels (especially arteries).
Systolic is the maximum arterial pressure when the ventricle contracts and blood is pumped into the arterial system.
Diastolic is the minimum pressure when the ventricle is relaxed and blood is returned to the heart via the veins.
What is the pulse pressure ?
The difference between the systolic and diastolic blood pressure
What is Peripheral resistance ? Where is it the highest ?
The result of the narrow nature of arterioles and capillaries, the narrower the vessel, the higher the resistance.
Arterioles have the highest resistance.
What happens to blood pressure as it travels down the systemic circulation ?
Blood pressure decreases as you go down the systemic circulation due to peripheral resistance to blood flow.
What are the components of blood ?
Blood is 55% plasma, and 45% formed elements (E.g. Erythrocytes, Leucocytes, Platelets).
What are the components of Plasma ?
Plasma is 92% water, the rest is electrolytes and plasma proteins.
Describe 3 Plasma proteins
Albumin - Maintains Osmotic Pressure
Globulins - Transport proteins and anti-body precursors
Fibrinogen - Polymerizes to form insoluble Fibrin
If you take away Fibrinogen and other clotting factors from Plasma, what are you left with ?
Serum
What are the formed elements of the blood ? Where do they originate ?
99% Erythrocytes, Platelets (Thrombocytes) and Leucocytes.
The formed elements originate from precursors in the bone marrow.
Describe Erythrocytes
Bi-concave cells which anucleate. They circulate for 110-120 days then the components are recycled by macrophages.
Mature Erythrocytes do not possess most Organelles because they are packed with Haemoglobin.
Describe Thrombocytes
Cytoplasmic fragments of Megakaryocytes (large bone marrow cells) involved in blood clotting (aka platelets).
Describe the role of calcium ions and Leucocytes in clot formation
Platelets adhere to collagen of injured vessels, releasing mediators which cause blood vessels to constrict (Vasoconstriction).
Ca2+ ions help in signalling thrombocytes to aggregate
Leucocytes help fight infection, they are divided into granulocytes and a granulocytes.
What are the 3 different types of Granulocytes ?
Neutrophils
Eosinophils
Basophils
What do Neutrophils do ?
They are Granulocytes, they are involved in the initial response to infection, control phagocytosis and are the main component of Pus.
What do Eosinophils do ?
They are Granulocytes. They are Phagocytic, participate in allergic reactions and destruct parasites.
What do Basophils do ?
They are Granulocytes. They release anti-coagulants e.g. Heparin and are involved in Hypersensitivity reactions (release Histamine).
What are the 2 different types of Agranulocytes ?
Lymphocytes
Monocytes (Phagocytes or Macrophages)
What is Haematocrit ?
How much space (volume) in the blood is occupied by red blood cells
What is a normal Haematocrit value for adults ?
Around 45%.
Describe Haemoglobin
Haem - Iron containing Porphyrin ring (Fe2+)
Globin - Tetrameric protein (2 alpha, 2 beta subunits)
Summarise capillary action in relation to blood pressure
When the blood pressure is greater than the Osmotic pressure, filtration is favoured and fluid tends to move out of the capillary.
When the blood pressure is lower than the Osmotic pressure, reabsorption is favoured and fluid tends to enter the capillary.
Name the 3 compartments in which fluid can exist in the body
- Intravascular (in the blood vessels)
- Intracellular (in the cells)
- Interstitial (in between cells)
What is the lymphatic system ?
The network of vessels which circulate fluid from the interstitial space into the Cardiovascular system.
Describe the function and flow of the Lymphatic system
Lymphatic flow is aided by osmotic pressure. Interstitial fluids enter the lymphatic system via lymphatic capillaries.
Lymph flows into larger and larger vessels propelled by skeletal muscle contraction and one-way valves.
Enters the thoracic duct which drains into veins leading to the right atrium.
Describe the function of lymph
Proteins leaked from the blood are returned into the circulating blood.
Micro organisms are carried to the lymph nodes.
Lymph nodes contain lymphocytes and macrophages which are components of the immune system.
What is the circulatory system ?
The movement of nutrients, gases and waste products to and from cells
