Topic 6: Human Physiology 6.2 The Blood System D.4 The Heart Essential Questions: 6.2 The blood system continuously transports substances to cells and simultaneously collects waste products. D.3 The chemical composition of blood is regulated by the liver. D.4 Internal and external factors influence the heart function.
Our Circulatory System System comprised of a heart, blood vessels, & lymph glands Work together to supply the body tissues with nourishment and collect waste materials.
Organization of Arteries, Arterioles, Capillaries, Venules and Veins Arteries, Veins, Capillaries Cross Section of an Artery and a Vein
Arteries Have a thick outer layer of longitudinal collagen and elastin fibers To avoid leaks and bulges Thick walled To withstand high pressure Narrow Lumen Maintains high pressure inside arteries Circular elastic fibres and muscle fibres (elastic-like tissues) To withstand the pressure from the heart s beating To help pump blood after each contraction of heart
Capillaries Connect arteries to veins Wall is one cell thick Thus short distance for diffusion to occur Thin-walled Porous Allows plasma to leak out and form tissue fluid Phagocytes can also pass through pores Small diameter (narrow lumen) Blood cells pass through in single file Allows for many capillaries to fit into a small space Semi-permeable membrane allows nutrients, oxygen, and water to diffuse from blood into the tissues
Veins Thin outer layer of longitudinal collagen and elastin fibres Because pressure is low Thin, collapsible walls Few circular elastic fibres and muscle fibres as blood does not flow in pulses Nearby muscles can help push blood back toward heart Wide Lumen Accommodate the slow flowing blood Valves Prevent blood from reversing flow
Cross Section of Blood Vessels
Histology of Arteries & Veins Source: legacy.owensboro.kctcs.edu
Comparison of Arteries, Veins and Capillaries From Pearson HL Biology
Atherosclerosis Developed by deposits of plaque (cholesterol, lipids, calcium, cell debris) accumulate at a tear in the inner layer of the artery Hardens, and occludes the lumen Blood flow to tissues decreases and a clot can become lodged and completely obstruct circulation Can lead to heart attack
The Heart
The Heart - Valves
Different names for the valves of the heart: From Pearson HL Biology
Myogenic Control of the Heart Heart is made up of cardiac muscle Cardiac muscle is MYOGENIC - meaning it naturally contracts and relaxes (originates from the heart itself) It receives no control from a nerve to make it contract Its AUTOMATIC! Some control by autonomic nervous system Responds to changes in body AUTOMATICALLY Example: increased body activity = running Electrical impulses causes regular contractions of the atria first, then the ventricles = heartbeat
Blood Composition Transport (Highway) around body nutrients, Gases (eg. oxygen and carbon dioxide) Hormones (Communication, Homeostasis) Antibodies, leucocytes (WBC) urea Heat
Blood Composition Plasma Fluid carries all other components of blood, nutrients and wastes Erythrocytes (RBC s) Produced in bone marrow (of large bones) Transports oxygen and carbon dioxide
Blood Composition Lymphocytes and Phagocytes (WBC s) Platelets Produced in bone marrow Belongs to immune system Cell fragments that aid in blood clotting A drop of blood contains approximately: - 5 million RBC - 10,000 WBC - 250,000 platelets
Topic 6: Human Physiology 6.2 The Blood System D.4 The Heart Essential Questions: 6.2 The blood system continuously transports substances to cells and simultaneously collects waste products.. D.4 Internal and external factors influence the heart function.
Our Circulatory system is a double circulatory system. It has two parts: Lungs the right side of the system deals with deoxygenated blood. the left side of the system deals with oxygenated blood. Body cells
Types of Circulation 1) Pulmonary - movement of blood à heart - lungs heart 2) Systemic - Movement of blood à heart body heart 3) Coronary - blood vessels that supply the muscle of the heart with oxygen/nutrients and remove waste products
Pulmonary Circulation Red portion of heart and red blood vessels carry oxygen-rich blood. Blue portion of heart and blue blood vessels carry oxygen-poor blood.
Cardiac Cycle - Series of events referred to as one heartbeat - Frequency of the cardiac cycle is your heart rate (measured in beats per minute) - 80 beats min -1 = 80 cardiac cycles every minute Systole (sis-tol-ee) Diastole (di-as-tol-ee) Contraction of the heart Relaxation of the heart Note: Both atria contract at the same time, and both ventricles contract at the same time, just a moment later then the atria
Diastole (= 60-80 mmhg adults) Both Chambers are at rest (no contracting) Minimum pressure in the arteries Atrial pressure is slightly higher then ventricular pressure keeping the left atrioventricular valve open Blood moves passively from atrium into ventricle The valve of the aorta is kept closed = no backflow
Contraction Systole (= 90-120 mmhg adults) Maximum pressure on the arteries Atria in Systole first generates a little pressure to move any remaining blood into the ventricle Ventricles in systole pressure inside is greater then the atrium so the valves close to prevent backflow (=lub) Ventricular pressure builds up until pressure becomes greater in the ventricle then the aorta causing the semilunar valve to open. Blood is forced into aorta Ventricle finishes contraction and semilunar valve closes (=dub)
Blood Pressure An adult is considered suffering from hypotension if the diastolic reading is < 60 mmhg and systolic reading is < 90 mmhg Prehypertension if the diastolic reading is 81 89 mmhg and systolic reading is 121 139 mmhg Stage 1 Hypertension if the diastolic reading is 90 99 mmhg and systolic reading is140 159 mmhg Stage 2 Hypertension if the diastolic reading is 100 mmhg and systolic reading is 160 mmhg
Occlusion in Coronary Artery Blockage of one of the three major coronary arteries or their branches Heart (or a portion of it) becomes deprived of oxygen = myocardial infarction peir.path.uab.edu http://nursingcrib.com/
Coronary Circulation Vessels deliver oxygen rich blood to the heart Highly affected by atherosclerosis which can cause angina or heart attack From A.D.A.M
Myogenic Control of the Heart Cardiac cycle initiated by small patch of muscle called the SA Node (sino-atrial node) or PACEMAKER This node sets the rhythm for all cardiac muscle (not the brain) For a heart rate at 72 beats/min, the SAN generates an action potential every 0.8 seconds (at a regular frequency) The pacemaker cells have a built-in rhythm that is faster than all other heart cells
Myogenic Control of the Heart SA node sends out an action potential (AP) and spreads out through the atria leading to systole (contraction) SA node s AP reaches the atrioventricular node (AV node) located in the lower wall of right atrium/septum AV node sends out a new AP that spreads to both ventricles after a 0.1 second delay Purkinje fibres help spread the AP through the thick walls of the ventricles causing ventricular systole
Electrocardiograms (ECG s) Used to measure heart rate Each event in the cardiac cycle has a distinctive waveform Every repeating pattern is a representation of one cardiac cycle
P wave shows voltage of AP from SA node = atrial systole How to Read an ECG Q point AV node sends its impulse QRS complex AP from the AV node spreads down Purkinje fibres within ventricles (=ventricular systole) T wave repolarization of AV node (another heart beat cannot occur until repolarization is complete)
Electrocardiograms (ECG s)