General Biology 2

• Blood vessels


  Channels or conduits through which blood is distributed to body tissues
• Capillaries


  Tiny blood-containing structures that connect arterioles to venules. They are the smallest and most abundant form of a blood vessel in the body.
• Lungs


  A pair of spongy, air-filled organs located on either side of the chest (thorax)
• Heart


  Pumps blood through the network of arteries and veins
• There is a great difference between animals and plants in terms of the part involved in transport. However, they have a common function of nourishing the cells and supplying them with their basic needs.
• Providing cells with hormones, nutrients, and gases is essential to the growth and development of animals and plants.
• Transport in animals

  • Varies depending on size, complexity, and habitat of an organism
• Transport in simple animals (sponges and cnidarians)

  1. Gas exchange happens between the water from the environment and the circulating body fluid in the organism

  2. In sponges, water passes through a series of chambers in the body to the spongocoel, the central cavity, where enough gas exchange happens directly with the cells

  3. In cnidarians such as the hydra, each cell is directly in contact with the external environment or the gastrovascular cavity since the body wall is only one-cell thick
• Roundworms (pseudocoelomates)


  Body fluid is used for circulation, accomplished by the movement of the body against the fluids that are directly in contact with tissues and organs
• Types of circulation


  • Open circulation
  • Closed circulation
• Open circulatory system


  The circulating fluid or hemolymph does not pass through enclosed tubes; instead, it is pumped by the heart to a network of channels and cavities (hemocoels) throughout the body. Gas exchange takes place in this network of channels and cavities.
• Closed circulatory system


  The blood or circulating fluid passes within blood vessels that transport blood away from and back to the heart.
• Animals with open circulation


  • Insects and other arthropods
• Animals with closed circulation

  • Earthworms
• Vertebrates exhibit a closed type of circulation. They all have a heart and blood vessels through which the blood circulates.
• Despite variations in the number of heart chambers, vertebrates' circulatory systems all function in supplying nutrients and gases to the different parts of the body and in collecting metabolic wastes.
• Circulatory system


  Supplies gases, nutrients, and hormones to the different parts of the body and collects metabolic wastes for acid-base balance and immunologic reactions. It is also indispensable in regulating homeostatic reactions of the body.
• Human heart


  • A muscular organ that pumps blood to all parts of the body
  • Develops in an embryo about four weeks following fertilization
  • Beats around 2.5 billion times without interruption in an average life span
  • Beats around 72 times per minute in a normal adult, pumping around 5.5 liters of blood
• The heart can beat three times as fast as the normal rate during a strenuous exercise or when you get over excited, e.g. about 180 to 195 beats per minute.
• Cardiac muscle


  An involuntary, striated type of muscle with associated nervous and connective tissues that makes up the heart
• Structure of the heart

  • Has its own cavity, the pericardial cavity, and is covered by the pericardium
  • A septum divides the heart into two sides: the right side receives deoxygenated blood collected from the different parts of the body, while the left side receives oxygenated blood from the lungs
  • Each side of the heart is divided into upper chambers (atria) and lower chambers (ventricles)
  • One-way valves called atrio-ventricular valves are located between the upper and lower chambers

  
• Flow of blood to the heart

  1. Non-oxygenated blood from different parts of the body enters the superior and inferior venae cavae and fills the right atrium

  2. The tricuspid valve between the right atrium and right ventricle opens, bringing blood to the right ventricle

  3. The tricuspid valve closes when blood reaches the right ventricle to prevent regurgitation

  4. From the right ventricle, blood is pumped into the pulmonary arteries and then flows to the capillaries of the air sacs in the lungs

  5. In the lungs, blood gives off carbon dioxide and some oxygen is picked up
• Right side of the heart


  Receives deoxygenated blood collected from different parts of the body
• Left side of the heart

  Receives oxygenated blood from the lungs
• Heart


  • Divided into upper and lower chambers
  • Upper chambers are called atria
  • Lower chambers are called ventricles
• Atrio-ventricular valves


  One way valves located between the upper and lower chambers
• Flow of blood to the heart

  1. Non-oxygenated blood enters superior and inferior venae cavae and fills the right atrium

  2. Tricuspid valve opens bringing blood to the right ventricle

  3. Tricuspid valve closes when blood reaches the right ventricle to prevent regurgitation

  4. Blood pumped from right ventricle into pulmonary arteries

  5. Blood flows to capillaries in air sacs in lungs

  6. Blood gives off carbon dioxide and takes in oxygen

  7. Oxygenated blood flows to pulmonary veins and into left atrium

  8. Mitral valve opens and oxygenated blood is pumped into left ventricle

  9. Aortic valve opens as pressure increases in left ventricle
• 'Lubb dupp' sound


  • 'Lubb' sound caused by closing of AV valves during ventricular contraction
  • 'Dupp' sound caused by snapping of SV valves as blood moves from ventricles to atria
• Systemic circulation


  Oxygenated blood delivered from aorta to different parts of body
• Blood


  • Internal circulating medium of the human body
  • Main function is to carry nutrients, oxygen, and remove carbon dioxide and waste
• Components of blood


  • 55% plasma
  • 45% blood cells (erythrocytes, leucocytes, thrombocytes)
• Plasma


  Liquid part of blood, composed of water, proteins, electrolytes, and other substances
• Blood vessels


  • Serve as 'highways' through which blood is circulated in the body
  • Types: arteries, veins, capillaries
• Arteries


  • Thick-walled vessels that allow passage of oxygenated blood
  • Largest artery is the aorta
• Veins


  • Thin-walled vessels that carry non-oxygenated blood towards the heart
  • Largest veins are the superior and inferior venae cavae
• Capillaries


  • Microscopic blood vessels that connect small veins and arteries
  • Site of exchange of materials between blood and cells
• Valves


  • Flaps or tissues that prevent backward flow or regurgitation of blood
  • Located between atrium and ventricle, and at base of arteries attached to heart
  • Also found in large veins along lower extremities
• Heart valves


  • Bicuspid, tricuspid, and aortic valves

  
• Patterns of circulation


  1. Pulmonary circulation: blood from heart to lungs and back to heart

  2. Systemic circulation: blood from aorta to all parts of body

  3. Coronary circulation: blood supply to the heart itself

  4. Renal circulation: blood through kidneys and back to heart
• Blood circulation is an essential bodily function that supplies vital organs with oxygen and nutrients