Please enable JavaScript.

Coggle requires JavaScript to display documents.

Chapters 42 and 44 (Circulatory systems link exchange surfaces with cells…

- - - - Fluid is called hemolymph, also bathes body cells
      - arthropods and some molluscs have open circulatory systems
      - contraction of the heart pumps the hemolymph through the vessels and into interconnected sinuses
    - - blood is confined to vessels
      - one or more hearts pump blood into smaller vessels that branch into smaller ones
      - Annelids, cephalopods, and all vertebrates
  - - - returns to its starting point in a single circuit loop
      - animals that have single circulation have a heart with two chambers: an atrium and a ventricle
      - In a fish, blood pumps to the capillary bed in the gills where there's diffusion of Oxygen gas
        
        when blood leaves the gills, capillaries converge together to carry oxygen rich blood to capillary beds
    - - two circuits of blood flow
      - pumps for the two circuits are combined into the heart
      - Pulmonary Circuit
        
        the heart pumps oxygen poor blood to capillary beds
        
        gas exchange takes place in the lungs
      - Systemic Circuit
        
        begins with the left side
        
        heart pumping oxygen-enriched blood from gas exchange tissues to capillary beds in organs an tissues throughout the body
        
        the now oxygen poor blood returns to the heart, completing the circuit
- - - - functions in both osmoregulation and excretion
      - kidneys consist of tubules
      - typically nonsegmented
- - - - when contracts it pumps, when relaxes its chambers fill with blood
        
        contraction phase: systole
        
        relaxation phase: diastole
      - one complete of pumping and filling is the cardiac cycle
  - - - produces electrical impulses
      - spread rapidly within heart tissue
      - ECG or EKG measure the electrical activity of the heart
- - - - flows from high to low pressure
      - contraction of heart ventricle generates blood pressure
      - Changes in Blood Pressure during the Cardiac Cycle
        
        Systolic Pressure: arterial blood pressure is highest when the heart contracts during ventricular systole
        
        during diastole, elastic walls snap back
        
        lower but still substantial blood pressure when the ventricles are relaxed (diastolic pressure)
      - Regulation of Blood Pressure
        
        Vasoconstriction
        
        increases blood pressure upstream in the arteries
        
        when smooth muscle relaxes, arterioles undergo vasodilation
        
        NO (nitric oxide) is a major inducer of vasodilation and endothelin is a potent inducer of vasoconstriction
- - - - ventilation maintains the partial pressure gradients of O2 and CO2 across the gill
      - most animals with gills move water over the gills or move their gills through water
      - fishes use countercurrent exchange
        
        exchange of a substance or heat between two fluids flowing in opposite directions
        
        very efficient
- - - - inflates the lungs with forced airflow
      - male frogs puffing themselves up in aggressive or courtship ways disrupts the breathing cycle
      - expanding the thoracic cavity during inhalation involves the rib muscles and the diaphragm
        
        contraction pulls the ribs upward and the sternum outward
- - - - marine animals
        
        face no substantial challenges in water balance
        
        transport specific solutes that establish levels in hemolymph
        
        marine bony fish like cod constantly lose water by osmosis
        
        balance it by drinking a lot of seawater
      - no tendency to gain or lose water
    - - these animals live in environments that are uninhabitable for osmoconformers (freshwater animals)
        
        body fluids must be hyperosmotic because the cells cannot tolerate salt concentration as low as that of lake or river water
        
        face the problem of gaining water by osmosis
        
        water balance relies on excreting large amounts of dilute urine
- - - - animals that excrete it need a lot of water
      - most common in aquatic species
      - in many invertebrates, ammonia release occurs across the whole body surface
    - - most terrestrial animals and many marine species excrete urea
      - product of an energy-consuming metabolic cycle that combines NH3 with CO2 in the liver
      - advantage for urea is that is has low toxicity; disadvantage is its energy cost
    - - birds, land snails, many reptiles and insects excrete uric acid
      - nontoxic and doesn't relatively dissolve in water
      - can be excreted as a semisolid paste without much water loss
      - more energetically expensive than urea
- - - - essential for production of urine that is hyperosmotic to body fluids
    - - distal tubule plays a role in regulating potassium and sodium chloride concentration of body fluids
      - descending loop of Henle and an ascending loop of Henle