Transport in humans Part 2

• Pressure changes in left side of heart

  1. Slight increase in pressure due to left atrium systole
  2. Left ventricle systole, causing bicuspid valve to close
  3. Pressure in left ventricles continues to rise
  4. Pressure in left ventricle higher than aorta, forcing semi-lunar valve to open

  
• Pressure changes in left side of heart

  5. Left ventricle diastole, causing pressure of left ventricle to drop lower than aorta. Semi-lunar valves close

  6. Ventricular pressure continues to decrease

  7. Ventricular pressure lower than atrial pressure, causing bicuspid valve to open

  8. Slight increase as blood enters left ventricle from left atrium

  9. Cycle repeats

  
• Pressure changes in right side of heart

  • Same as left side of heart
  • Increase in aorta and right ventricle not as much
• Sinoatrial Node

  • Acts as pacemaker
  • Found in right atrium
  • Generates an electrical signal to initiate contraction of atria
  • For average person of 72 beats a minute, signal sent out every 0.8 seconds
• Functions of sinoatrial node

  1. Pacemaker generates wave of signals to initiate contraction of atria
  2. Signals delayed at AV nodes
  3. Signals pass to heart apex
  4. Signals spread throughout ventricles
  5. These electrical signals can be recorded as electrocardiogram
• Control of heartbeat

  • Pacemaker influenced by nerves, hormones, body temperature, exercise
  • Basic heart rate controlled by SA node
  • Control of heartbeat achieved by nerves/non-nerves control system
• Control of heartbeat

  • During exercise
  • Increased level of oxygen needed for cellular respiration
  • Need to remove the increase level of carbon dioxide accumulating in bloodstream
  • Medulla chemically senses the increased level of carbon dioxide
  • Sends a signal to cardiac nerve to increase rate of heartbeat to appropriate level
  • Also sends a signal to SA node to change timing of heartbeat
• Control of heartbeat

  • After exercise
  • Carbon dioxide level decreases
  • Medulla chemically senses the decrease in carbon dioxide
  • Sends a signal to vagus nerve
  • Results in SA node returning rate of heartbeat to normal level
  • Chemical
  • Adrenal gland secretes adrenaline into bloodstream
  • Adrenaline causes SA node to fire more frequently, increasing rate of heartbeat
• Artery and vein

  1. Endothelium
  2. Smooth muscle
  3. Connective tissue
  4. Endothelium
  5. Capillaries
  6. Basement membranes
  7. Artery
  8. Veins
  9. Arterioles
  10. Venules

  
• Blood pressure

  • From arteries to capillaries to veins, pressure decreases


  Speed

  • From arteries to capillaries to veins, speed decreases and then increases
• Artery

  • Receives blood directly from heart + carries blood away from heart
  • Thick elastic muscular walls to withstand high arteriole pressure
  • Elasticity allows walls to stretch + recoil back to push blood in spurts
  • Muscles constrict and dilate
  • No valves except for semi-lunar valves at start of aorta + pulmonary artery
  • Small lumen
  • Carry oxygenated blood
• Veins

  • Carry blood towards heart
  • Thin, less elastic and muscular walls due to lower blood pressure
  • Blood flow is assisted by action of skeletal muscles on veins and smooth muscles contraction
  • Semi-lunar valves present to prevent backflow of blood
  • Larger lumen
  • Carry deoxygenated blood
• Capillaries

  • Walls are one cell thick
  • Lumen is size of one RBC
• Tissue fluid

  • Higher pressure at arteriole end of capillaries pushes blood plasma out through capillary wall
  • Blood plasma becomes tissue fluid around cells
  • RBC, platelets and proteins remain in capillaries
  • Small substances like salts, water, amino acids + WBC able to diffuse out of capillaries
  • Generally, anything that comes out of capillaries = tissue fluid
• Exchange of materials between blood and cells through tissue fluid

  1. Movement of dissolved food substances and oxygen
  2. Movement of excretory waste products
  3. Capillary wall
  4. Bell shaped RBC
  5. WBC squeezing through capillary wall

  
• Exchange of materials between blood and cells through tissue fluid

  • WBC squeeze through capillary wall to tissue fluid
  • RBC move through capillary lumen in single file + changes shape to bell-shape
  • Dissolved food substances + oxygen diffuses from blood, tissue fluid then cells
  • Metabolic waste products diffuses from cells, tissue fluid and then blood
• Blood components

  1. Plasma - (55 percent)
  2. Red blood cells ~ (45 percent)
  3. Platelets + WBC - (less than 1 percent)
• Plasma

  • Pale yellow fluid
  • 90 percent water
  • Solvent for carrying other substances
  • 10 percent transported dissolved substances
  • Mineral salts
  • Osmotic balance, pH buffering, regulation of membrane permeability
  • Soluble proteins
  • Osmotic balance, pH buffering, clotting, defense
  • Gases
  • Excretory products
  • Hormones
  • Substances transported by blood
  • Nutrients
  • Gasses
  • Hormones
  • Waste products
• Red blood cell

  • Transport oxygen and carbon dioxide
  • 5 million per mm^3 of blood
  • Circular, flattened and biconcave shape
  • Contains haemoglobin
  • No nucleus and mitochondria
  • Elastic + changes shape to bell shape to fit through capillary wall
  • Produced in the bone marrow
  • Life span is 3-4 months
  • Worn out red blood cell is destroyed in the spleen + released haemoglobin is broken down in the liver
• Haemoglobin

  • Consists of four protein globin chain, each centered around a heme group
  • Each heme group consists of a porphyrin ring and a iron atom in the center
  • Has two alpha chains and two beta chains
• Blood transfusion

  • Blood type O = Universal donors
  • Blood type AB = Universal recipients
• Red blood cell and blood groups

  • Antigens A and B can be found on the RBC's surface membranes
  • Natural antibodies A and B found in plasma
  • Natural antibodies will not react with antigens on RBC
  • May mix with antigens on RBC of another person
  • Causes clumping of RBC
  • Antigens and antibodies of the same type will agglutinate
  • During blood fusion, only consider the effects of the recipient's plasma on the donor's RBC
• Lymphocytes

  • Large round nucleus + small amounts of cytoplasm
  • Non-granular cytoplasm
  • Round shape
  • Movement is very limited
  • Produces antibodies for immune defense
  • Antibodies destroys bacteria
  • Antibodies clump bacteria together so it is easier for phagocytes to engulf
  • Antibodies neutralise toxins produced by bacteria
• Phagocytes

  • Lubed nucleus and huge amount of cytoplasm
  • Granular cytoplasm
  • Mobile
  • Irregular shape
  • Phagocytosis
  • Approach, ingests foreign particles and digests them intracellularly
  • In the process, phagocytes are killed
  • Dead phagocytes and bacteria make up pus
• White blood cells

  • Larger than RBC but fewer
  • Ratio of RBC to WBC = 700:1
  • 5000 to 10000 per mm^3
  • Produced by stem cells in bone marrow
  • Life span is a few days
  • Fight diseases
  • Feature
  • Colourless and irregular shape
  • No haemoglobin and contains nucleus
  • Can move and change shape to fit through capillary walls into tissue fluid
  • Has two types
  • Lymphocytes
  • Phagocytes
• Platelets

  • 250000 to 400000 per mm^3 of blood
  • Not true cells
  • Membrane bound fragments of cytoplasm from certain bone marrow cells
  • Essential for blood clotting