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Chapters 42 and 44 (Circulation and Gas Exchange (Circulatory System Types…

- - - - Arteries – carry blood from the HEART to ORGANS.
      - Arterioles – what arteries branch into
      - Venules – what capillaries converge into
      - Veins – venules converge into veins and carry blood back to the HEART.
      - Capillaries – microscopic vessels. Dissolved gases and other chemicals are exchanged by diffusion.
  - - - Single circulation – blood travels through the body and returns to its starting point in a single loop. EX. Shark, rays, bony fish.
      - Double circulation – pulmonary circuit and systemic are double pumps both located within the heart.
      - One atrium, one ventricle – blood entering the heart collects in the atrium before transfer to the ventricle.
      - Two atrium, one ventricle – heart is divided but consists of one ventricle. Blood flow continues to the skin as gas exchange. Incomplete division of the ventricle.
      - Two atrium, two ventricles – heart has two atria’s and two completely divided ventricles. Left side of heart receives and pumps oxygen rich blood. Right side receives and pumps oxygen poor blood
  - - - Cardiac cycle – when heart contracts, it pumps blood; when it relaxes, its chambers fill with blood. One complete sequence of pumping and filling is referred to as the cardiac cycle.
      - Systole – the contraction phase of the cycle is called systole, pumping of blood.
      - Diastole – the relaxation phase. Chambers fill with blood.
      - Cardiac output (CO) – the volume of blood each ventricle pumps per minute.
      - Heart rate – 1 of 2 factors that determine cardiac output. The rate of contraction (number of beats per minute).
      - Stroke volume – 2 of 2 factors that determine cardiac output. The amount of blood pumped by a ventricle in a single contraction.
      - Sinoatrial node SA – pacemaker, sets the rate and timing at which all cardiac muscle cells contract. Produces electrical impulses. These impulses generate currents that can be measured when the y reach the skin via body fluids.
      - Electrocardiogram ECG/EKG – electrodes placed on the skin record currents, thus measuring electrical activity of the heart.
      - Atrioventricular node AV – relay point, impulses are delayed for about 0.1 second before spreading to the heart apex. This delay allows the atria to empty completely before the ventricles contract signals travel through apex and ventricular walls.
      - Bundle branches and purkinje fibers atria – contractions are conducted through these specialized structures, triggering ventricular contractions.
  - - - Artery structure – walls are thick, strong and elastic. Carry oxygenated blood from heart to body.
      - Vein structure – not thick, contain valves. Carry oxygen poor blood from body to heart.
      - Arteries thick walls – the pressure of blood is different, and arteries contain pulse.
      - Arteries conveys blood to so many capillaries that the total cross section area is much greater. Increase of the cross-section area decreases velocity from the arteries to capillaries.
      - After passing through capillaries, blood speeds up as it enters the venules and veins, which have smaller total cross-sectional areas.
      - Valves in veins regulate blood pressure via muscles. When muscles contact the blood within the veins is squeezed up the vein and the valves open. Standing too long cause blood pooling by putting pressure on lower leg veins.
  - - - Blood pressure is measured by systolic and diastolic pressure. A normal blood pressure reading is 120/80. 120 measures the systolic pressure, 70 measures the diastolic pressure.
      - Blood pressure changes throughout the day for example when your angry blood pressure goes up, when exercising more blood is required to return back to the heart.
      - 140< systolic and 90< diastolic is considered high blood pressure. Having hypertension increases the risk of heart attack, heart failure and sudden cardiac death.
  - - - Capillaries are where fluids, gases, nutrients and waste are exchanged between blood, body tissues, and intestinal fluid. There are the smallest blood vessels in human bodies. They are 5 to 10 microns in diameter.
      - Two factors that can alter blood. 1. Constriction or dilation of the arterioles that supply capillaries. 2. Precapillary sphincters that open and close that redirect blood into specific capillaries.
      - When to dilate (open) capillaries – when the body is in need of higher blood flow and more oxygenated blood.
      - When to constrict (close) capillaries – when blood flow needs to be restricted or decreased.
      - Examples of dilation – high exercise, when trying to lower blood pressure.
      - Examples of constriction – when it is cold.
  - - - Blood pressure tends to drive fluid out of the capillaries, and the presence of blood proteins tends to pull fluid back. Fluid leaks into surrounding tissues. Plasma at this point is called interstitial fluid.
      - The lost fluid and proteins within it are recovered and returned to the blood via the lymphatic system. Fluid diffuses into the lymphatic system via a network of tiny vessels intermingles with capillaries. The recovered fluid called “lymph”, circulates within the lymphatic system before draining into a pair of large veins of the cardiovascular system at the base of the neck.
      - Disruptions in the movement of lymph often result in fluid accumulation, or edema, in affected tissues. For example, certain species of parasitic worms that lodge in lymph vessels and thereby block lymph movement cause elephantiasis, a condition marked by extreme swelling in limbs or other body parts.
      - Lymph nodes – inside each lymph node is a honeycomb of connective tissue with spaces filled by white blood cells, which function In defense. When the body’s fighting an infection, the white blood cells multiply rapidly, and the lymph nodes becomes swollen or tender.
  - - - Fluid components of blood – ions (blood electrolytes, sodium, potassium, calcium, magnesium, chloride, bicarbonate) and plasma proteins (albumin, immunoglobulins, apolipoproteins, fibrinogen.
      - Cellular components of blood – leukocytes (white blood cells, basophils, lymphocyte, eosinophils, neutrophils, monocytes), Platelets, and erythrocytes (red blood cells).
      - Plasma – consists of ions and proteins, together with the blood cells, function in osmotic regulation. The percentage of blood that is cellular 45%.
      - Cellular elements
      - Erythrocytes – red blood cells, transport O2, generate ATP.
      - Leukocytes – contains five major types of white blood cells. Fight infections.
      - Platelets – pinched off cytoplasmic fragments of specialized bone marrow cells. Serve both structural and molecular function.
      - Cells are produced in bone marrow. Red blood cells survive for 120 days before being replaced.
  - - - Sickle cell disease – an abnormal form of hemoglobin polymerizes into aggregates. Aggregates are large enough to distort the erythrocyte into elongated, curved shape that resembles a sickle.
      - Consequences of sickle cell disease – impairs the function of circulatory system. Sickle cells often lodge in arterioles and capillaries, preventing delivery of O2 and nutrients and removal of CO2, and waste. Also reduces erythrocyte count.
      - How to get sickle cell – abnormality results from an alteration in the amino acid sequence of hemoglobin at a single position. Persist in population due carriers having the recessive allele of the disease, tends to be inherited.
  - - - Each year more than 750,000 people die due to cardiovascular disease, ranging from minor disturbances of vein or heart valve function to life-threatening disruptions of blood flow to heart or brain.
      - Atherosclerosis – the hardening of arteries by accumulation of fatty deposits. Develops by cholesterol. In atherosclerosis, damage to the arterial artery lining results in inflammation, the body reaction to injury.
      - LDL – delivers cholesterol to cells for membrane production.
      - HDL – scavenges excess cholesterol for return to the liver.
      - Myocardial infarction – heart attack, is the damage or death of cardiac muscle tissue resulting from blockage of one or more coronary arteries, which supply oxygen rich blood to the heart muscle.
      - Stroke – a stroke is the death of nervous tissue in the brain due to a lack of O2, usually result from rupture or blockage of arteries in the head.
      - Hypertension – contributor to heart attack and stroke. Systolic pressure above 140, a diastolic pressure above 90. Can be controlled by exercise and dietary.
  - - - Fish – obtains oxygen via gills by counter exchange.
      - Earthworm – receives oxygen via skin respiratory system.
      - Insect – receives oxygen via tracheal system. Respiratory surfaces enclosed within the body.
      - Mammal – depend entirely on lungs for gas exchange.
      - Tadpole – obtain oxygen by movement and gills.
      - Adult frog – has gills and lungs to obtain oxygen. Diffusion by external surfaces.
      - Squid – breath via mantle and long gills to obtain oxygen.
      - Crayfish – exoskeleton by means of gills
      - Lungs are more efficient on land and gills are efficient in water. Different environmental factors contribute.
      - Oxygen is needed for cellular respiration and for gas exchange. Importance for survival.
      - Oxygen enters the lungs then passes through the alveoli and into the blood. The oxygen is carried around the body in blood vessels. Carbon dioxide moves into the blood capillaries and is brought to the lungs to be released into the air during exhalation.
      - Partial pressure is the pressure that would be exerted by one of the gases in a mixture if it occupied the same volumes on its own.
      - Less oxygen in higher altitudes means lack of cellular respiration.
  - - - how frogs breathe – frog ventilates its lungs by positive pressure breathing, inflating the lungs with forced airflow. muscles lower the floor of an amphibian’s oral cavity, drawing in air through its nostrils. with the nostrils and mouth closed, the floor of the oral cavity rises, forcing air down the trachea. During exhalation, air is forced back out by the elastic recoil of the lungs and by compression of the muscular body wall.
      - How birds breathe - To bring fresh air to their lungs, birds use eight or nine air sacs situated on either side of the lungs. First, when birds breathe, they pass air over the gas exchange surface in only one direction. Second, incoming fresh air does not mix with air that has already carried out gas exchange.
      - Positive pressure – inflating the lungs with forced airflow.
      - Negative pressure – pulling, rather than pushing, air into their lungs.
      - How humans breathe - Using muscle contraction to actively expand the thoracic cavity, mammals lower air pressure in their lungs below that of the air outside their body. The increased air pressure in the alveoli forces air up the breathing tubes and out of the body. Thus, inhalation is always active and requires work, whereas exhalation is usually passive.
      - Diaphragm - Expanding the thoracic cavity during inhalation involves the animal’s rib muscles and the diaphragm, a sheet of skeletal muscle that forms the bottom wall of the cavity. The effect of the descending diaphragm is similar to that of a plunger being drawn out of a syringe
      - Tidal volume - The volume of air inhaled and exhaled with each breath
      - Vital capacity - The tidal volume during maximal inhalation and exhalation
      - Residual volume - The air that remains after a forced exhalation
  - - - Breathing control - Neural circuits in the medulla form a pair of breathing control centers that establish the breathing rhythm. When you breathe deeply, a negative-feedback mechanism prevents the lungs from overexpanding: During inhalation, sensors that detect stretching of the lung tissue send nerve impulses to the control circuits in the medulla, inhibiting further inhalation.
      - Determining breathing rate - In regulating breathing, the medulla uses the pH of the surrounding tissue fluid as an indicator of blood CO2 concentration. concentration leads to an increase in the concentration of H+ , lowering pH. Sensors in the medulla as well as in major blood vessels detect this pH change. In response, the medulla’s control circuits increase the depth and rate of breathing
      - Dissolved gasses affect blood ph – increase in carbon dioxide and subsequent decrease in pH reduce the affinity of hemoglobin for oxygen.
      - Bicarbonate neutralizes blood ph.
  - - - Hemoglobin is the carrier of oxygen to all the living cells for cellular respiration. Hemoglobin also assists in buffering the blood—that is, preventing harmful changes in pH. And it has a minor role in CO2 transport
      - Oxygenated blood is colored red, deoxygenated blood is blackish red.
      - Bohr shift - CO2 reacts with water, forming carbonic acid, which lowers the pH of its surroundings. Low pH, in turn, decreases the affinity of hemoglobin for O2, an effect called the Bohr shift.
      - Mammalian diving reflex – a physiological response to immersion that overrides basic homeostatic reflexes.
      - Myoglobin - high concentration of an oxygen-storing protein.
- - - - Osmoregulation – processes by which animals control solute concentrations and balance water gain and loss.
      - Osmolarity – the unit measurement for solute concentration. The number of moles of solute per liter f solution.
      - Osmoconformer - Because an osmoconformer’s internal osmolarity is the same as that of its environment, there is no tendency to gain or lose water. Many osmoconformers live in water that has a stable composition and hence have a constant internal osmolarity
      - Osmoregulator - : to control internal osmolarity independent of that of the external environment. To survive in a hypoosmotic environment, an osmoregulator must discharge excess water. In a hyperosmotic environment, an osmoregulator must instead take in water to offset osmotic loss.
      - Osmoregulation enables animals to live in environments that are uninhabitable for osmoconformers, such as fresh water and terrestrial habitats, or to move between marine and freshwater environments.
      - Osmoregulation also allows many marine animals to maintain an internal osmolarity different from that of seawater.
      - The osmoregulatory problems of freshwater animals are the opposite of those of marine animals. The body fluids of freshwater animals must be hyperosmotic because animal cells cannot tolerate salt concentrations as low as that of lake or river water
      - Osmosis – the movement of water or other solvent through a plasma membrane from a region of low solute concentration to a region of high solute concentration. Osmosis is a passive transport.
  - - - maintaining the fluid balance of their tissues requires that the relative concentrations of water and solutes be kept within fairly narrow limits. In addition, ions such as sodium and calcium must be maintained at concentrations that permit normal activity of muscles, neurons, and other body cells.
      - Salt glands, which are also found in sea turtles and marine iguanas, use active transport of ions to secrete a fluid much saltier than the ocean. Even though drinking seawater brings in a lot of salt, the salt gland enables these marine vertebrates to achieve a net gain of water.
      - Osmolarity of human blood – 295 mosm/kg, dehydration can cause this level to change.
      - When injecting someone with distilled water that does not have minerals the cells absorb less fluid and salts are lost in urine.
  - - - Nitrogenous waste - the most significant waste products are the nitrogenous breakdown products of proteins and nucleic acids. When proteins and nucleic acids are broken apart for energy or converted to carbohydrates or fats, enzymes remove nitrogen in the form of ammonia.
      - Ammonia - Animals that excrete nitrogenous wastes as ammonia need access to lots of water because ammonia can be tolerated only at very low concentrations. Therefore, ammonia excretion is most common in aquatic species.
      - Urea - urea is the product of a metabolic cycle that combines ammonia with carbon dioxide in the liver. Amphibians and terrestrial animals. Insufficient supply of water to produce ammonia.
      - Uric acid - Uric acid is relatively nontoxic and does not readily dissolve in water. It therefore can be excreted as a semisolid paste with very little water loss. Insects, land snails, and many reptiles, including birds, excrete uric acid.
  - - - Filtration. The excretory tubule collects a filtrate from the blood. Water and solutes are forced by blood pressure across the selectively permeable membranes of a cluster of capillaries and into the excretory tubule.
      - Reabsorption. The transport epithelium reclaims valuable substances from the filtrate and returns them to the body fluids
      - Secretion. Other substances, such as toxins and excess ions, are extracted from body fluids and added to the contents of the excretory tubule.
      - Excretion. The altered filtrate (urine) leaves the system and the body.
  - - - Protonephridia - form a network of dead-end tubules. the freshwater flatworms, protonephridia serve chiefly in osmoregulation. e parasitic flatworms, which are isoosmotic to the surrounding fluids of their host organisms, the main function of protonephridia is the disposal of nitrogenous wastes.
      - Metanephridia - Most annelids, such as earthworms, have metanephridia (singular, metanephridium), excretory organs that collect fluid directly from the coelom. The metanephridia of an earthworm have both excretory and osmoregulatory functions.
      - Malpighian tubules -outpocketings of the digestive tract. Insects and other terrestrial arthropods have organs called Malpighian tubules that remove nitrogenous wastes and that also function in osmoregulation.
      - Kidney - In vertebrates and some other chordates, a specialized organ called the kidney functions in both osmoregulation and excretion. Like the excretory organs of most animal phyla, kidneys consist of tubules.
  - - - Each nephron consists of a single long tubule as well as a ball of capillaries called the glomerulus. The blind end of the tubule forms a cup-shaped swelling, called Bowman’s capsule, which surrounds the glomerulus. Filtrate is formed when blood pressure forces fluid from the blood in the glomerulus into the lumen of Bowman’s capsule.
      - Processing occurs as the filtrate passes through three major regions of the nephron: the proximal tubule, the loop of Henle (a hairpin turn with a descending limb and an ascending limb), and the distal tubule. A collecting duct receives processed filtrate from many nephrons and transports it to the renal pelvis.
      - Each nephron is supplied with blood by an afferent arteriole, an offshoot of the renal artery that branches and forms the capillaries of the glomerulus. The capillaries converge as they leave the glomerulus, forming an efferent arteriole
        
        Branches of this vessel form the peritubular capillaries, which surround the proximal and distal tubules. Other branches extend downward and form the vasa recta, hairpin-shaped capillaries that serve the renal medulla, including the long loop of Henle of juxtamedullary nephrons.
    - - Proximal tubule - Reabsorption in the proximal tubule is critical for the recapture of ions, water, and valuable nutrients from the huge volume of initial filtrate. Processing of filtrate in the proximal tubule helps maintain a relatively constant pH in body fluids.
        
        Descending limb of the loop of Henle - Reabsorption of water continues as the filtrate moves into the descending limb of the loop of Henle. Here numerous water channels formed by aquaporin proteins make the transport epithelium freely permeable to water
        
        Ascending limb of the loop of Henle -The filtrate reaches the tip of the loop and then returns to the cortex in the ascending limb. This movement of NaCl out of the tubule helps maintain the osmolarity of the interstitial fluid in the medulla. In the thick segment of the ascending limb, the movement of NaCl out of the filtrate continues.
        
        Distal tubule - The distal tubule plays a key role in regulating the K+ and NaCl concentration of body fluids. This regulation involves variation in the amount of K+ secreted into the filtrate as well as the amount of NaCl reabsorbed from the filtrate
        
        Collecting duct - The collecting duct carries the filtrate through the medulla to the renal pelvis. Final processing of the filtrate by the transport epithelium of the collecting duct forms the urine
  - - - countercurrent systems, which expend energy to create concentration gradients, are called countercurrent multiplier systems. The countercurrent multiplier system involving the loop of Henle maintains a high salt concentration in the interior of the kidney, enabling the kidney to form concentrated urine.
      - The countercurrent-like characteristics of the loop of Henle and the vasa recta help to generate the steep osmotic gradient between the medulla and cortex.
      - The juxtamedullary nephron, with its urine-concentrating features, is a key adaptation to terrestrial life, enabling mammals to get rid of salts and nitrogenous wastes without squandering water
  - - - Vampire bat - The vampire bat’s ability to alternate rapidly between producing large amounts of dilute urine and small amounts of very hyperosmotic urine is an essential part of its adaptation to an unusual food source
      - Bird/reptiles - live in environments that are dehydrating. Like mammals, birds have kidneys with juxtamedullary nephrons that specialize in conserving water. main water conservation adaptation is having uric acid as the nitrogenous waste molecule.
      - Freshwater fish/amphibians - Freshwater fishes are hyperosmotic to their surroundings, so they must excrete excess water continuously. Their kidneys, which contain many nephrons, produce filtrate at a high rate. Freshwater fishes conserve salts by reabsorbing ions from the filtrate in their distal tubules, leaving water behind
      - Marine fish - The tissues of marine bony fishes gain excess salts from their surroundings and lose water. The main function of kidneys in marine bony fishes is to get rid of divalent ions, such as calcium, magnesium, and sulfate.
  - - - AHD - key hormone in the regulatory circuitry of the kidney. ADH brings about changes that make the epithelium more permeable to water. The resulting increase in water reabsorption concentrates urine, reduces urine volume, and lowers blood osmolarity back toward the set point
      - Osmoreceptor cells in the hypothalamus monitor the osmolarity of blood and regulate the release of ADH from the posterior pituitary.
      - Vasopressin causes vasoconstriction and increases reabsorption of water by the kidneys.
  - - - RAAS - A second regulatory mechanism that helps maintain homeostasis by acting on the kidney.
      - The RAAS involves the juxtaglomerular apparatus (JGA), a specialized tissue consisting of cells of and around the afferent arteriole, which supplies blood to the glomerulus
      - Functioning as a hormone, angiotensin II raises blood pressure by constricting arterioles, which decreases blood flow to capillaries in the kidney
      - Angiotensin II also stimulates the adrenal glands to release a hormone called aldosterone. Aldosterone causes the nephrons’ distal tubules and collecting duct to reabsorb more Na+ and water, increasing blood volume and pressure
      - The resulting production of angiotensin II and release of aldosterone cause a rise in blood pressure and volume, reducing the release of renin from the JGA.
      - ADH, the RAAS, and ANP provide an elaborate system of checks and balances that regulate the kidney’s ability to control the osmolarity, salt concentration, volume, and pressure of blood.