Lesson 6 - 12.1 Circulatory System (Blood and Blood Vessels) PDF

Chapter 12: The Circulatory System 12.1 Structure and Function of Blood and Blood Vessels  The Circulatory System Now that your body has digested nutrients, the next step is to distribute these nutrients to the rest of the body This function is perform...

Chapter 12: The Circulatory System 12.1 Structure and Function of Blood and Blood Vessels  The Circulatory System Now that your body has digested nutrients, the next step is to distribute these nutrients to the rest of the body This function is performed by the circulatory system  The Circulatory System The three primary components of the circulatory system are: 1. Blood 2. Blood Vessels 3. Heart  The Two Circuit System Complex closed circulatory system Pulmonary circuit: delivers blood to the lungs Systemic circuit: delivers blood around the body Need a four-chambered heart  The Circulatory System: Facts The human circulatory systems is also sometimes called the cardiovascular system Our systems include 100 000 km of blood vessels This network of blood vessels supplies the one trillion cells in your body One blood cell takes one minute to make a complete circuit throughout your body  1. Blood Your body contains about 4 to 6 liters of blood Functions of blood: 1. Transports oxygen, water, nutrients, and other chemicals to cells 2. Removes waste products 3. Regulates body temperature 4. Fights infection 5. Heals wounds  1. Blood Components of Blood Red Blood White Plasma Platelets Cells Blood Cells  1. Blood: Plasma 55% of blood is made of plasma Plasma itself is 90% water The remaining 10% is proteins, dissolved nutrients and carbon dioxide Functions of Plasma: 1. Transports fatty acids and vitamins 2. Fights viral and bacterial  1. Blood: Red Blood Cells (Erythrocytes) ~41% of blood is made of red blood cells formed in the stem cell of bone marrow no nucleus Functions of Red Blood Cells: 1. Transports oxygen from the lungs to all tissues in the body  1. Blood: Red Blood Cells One drop of blood contains 5 million red blood cells Each red blood cell contains 250 million molecules of hemoglobin  1. Blood: Red Blood Cells Hemoglobin Cycle 1. Hemoglobin binds to oxygen in the lungs and releases it to tissues throughout the body 2. Once oxygen is released, the red blood cells transport carbon dioxide to the lungs  1. Blood: White Blood Cells (Leukocytes) 4% of blood is made of white blood cells and platelets Functions of White Blood Cells: 1. Guard against infection, fight parasites and kill bacteria  1. Blood: Platelets 4% of blood is made of white blood cells and platelets Cell fragments Functions of Platelets 1. Blood clotting (coagulation) Sticks to collagen fibres when there’s a cut Fibrinogen turns to fibrin → mesh  2. Blood Vessels Blood flows through the circulatory system through three types of blood vessels 1. Arteries 2. Capillaries 3. Veins  2. Blood Vessels: Arteries Arteries carry blood away from the heart, towards tissues The arteries are under pressure due to the heart’s pumping action This pressure helps to ensure that the flow of blood occurs in one direction As we look at arteries further and further away from the heart, they branch into smaller and smaller vessels known as capillaries  Arterioles The smallest artery, Vasoconstriction: diameter with smooth muscle in decreases (contraction) → its walls restricts blood flow Controlled by nerve Diverts blood to parts impulses of the body it’s most required – Relaxation = expansion Example: exercise → (increased blood flow) flow to lungs and – Cooling strategy muscles increased – Vasodilation  2. Blood Vessels: Capillaries Capillaries are microscopic blood vessels Connection between arteries and veins They are so narrow that blood cells must travel through them only a few at a time The reason why they are tiny is so that they can reach tissues easily  2. Blood Vessels: Veins Veins have thinner walls, larger diameters, and less smooth muscle than arteries. Blood in veins is under low pressure. Capillaries merge into venules, which join to form veins. Veins carry blood back to the heart. Valves ensure one-way blood flow. Skeletal muscle contractions squeeze veins, pushing blood upward. This helps blood overcome gravity to return to the heart. Blood pooling can occur when movement is limited.  Blood in the Circulatory System Why is that when you look at pictures of the circulatory system, blood appears as either blue or red?  Blood: Oxygenated and Deoxygenated The red colour represents blood that is oxygenated The blue colour represents blood that is deoxygenated Blood: Oxygenated and Deoxygenated  Blood: Oxygenated and Deoxygenated Oxygenated Deoxygenated Blood cell contains hemoglobin Blood cell contains hemoglobin bound to oxygen not bound to oxygen Blood appears red Blood appears blue From the heart, to the rest of From the rest of the body, to the the body heart Travels through arteries Travels through veins  Blood: Oxygenated and Deoxygenated Capillaries As the exchange of oxygenated and deoxygenated blood occurs at the capillaries, they are sometimes represented in drawings to as red-blue or purple  Blood: Carbon Dioxide When tissues receive all the oxygen required, they send carbon dioxide back to the heart, and out of the body through the lungs. How? Carbon dioxide molecules are transported in the blood from body tissues to the lungs by one of three methods: 1. Dissolution directly into the blood 2. Binding to hemoglobin 3. Carried as a bicarbonate ion Therefore, deoxygenated blood can also carry carbon dioxide if required.  ORGANS INVOLVED Heart Brain Accepts deoxygenated blood, Controls smooth pumps out oxygenated muscle in arterioles Liver Lungs Processes and removes Gas exchange toxins from blood with blood Stomach/ Kidneys Intestine Filters blood Absorption of nutrients into blood  BLOOD PRESSURE Pressure increases when heart contracts, decreases when it relaxes Overall volume significant determinant of pressure Systolic pressure: blood pressure in the arteries when the heart contracts – Normal = 120 mmHg Diastolic pressure: blood pressure in the arteries when the heart relaxes – Normal: 80 mmHg Blood pressure reported as: 120/80 Pressure drops the further away you get from the heart  HYPERTENSION Consistent blood pressure above the range of normal values (high blood pressure) Causes: – Kidney disease (more fluid left in bloodstream) – Medication – Age → artery walls lose elasticity → hold less volume – High sodium diets → kidney cannot remove excess