Circulation and Gas Exchange
Circulatory System Types
Open
blood may be present in the blood vessels for some time but it comes out of the blood vessels.
The internal organs are directly bathed in blood.
The blood flows from the heart into the arteries
no inter connecting vessels or capillaries between the arteries and the veins, as the blood comes out of blood vessels
occurs in annelids like leeches, arthropods, most of the molluscs and ascidians.
Closed
the blood remains inside the blood vessels and does not come out
The blood flows from arteries to veins through small blood vessels called capillaries
occurs in most of the Annelids, Cephalopods and Vertebrates
Characteristics
The speed of circulation is more rapid due to the presence of muscular and contractile blood vessels.
The supply and removal of materials to and from the tissues by the blood is enhanced, thereby increasing the efficiency of circulation.
The volume of blood flowing through a tissue or organ is regulated by the contraction and relaxation of the muscles of the blood vessels.
Characteristics
blood flows at a very low velocity and at low pressure due to the absence of smooth muscles.
There is direct exchange of materials between the cells and the blood because of the direct contact between them.
respiratory pigment, when present, is dissolved in the plasma of the blood and there are no red corpuscles.
Single
Blood passes through the heart only once on each circuit around the whole of the blood circulation system of the animal
Heart receives deoxygenated blood oxygenated as it passes through the gill capillaries then moves onward through the rest of the body
Fish
Double
Blood flows through heart twice during each circulatory cycle
Amphibians, Reptiles, and Mammals
Pulmonary circulation
Deoxygenated blood is pumped from the heart to the lungs, oxygenated blood returns to the heart from the lungs.
Systemic circulation
Oxygenated blood is pumped from the heart around the body (including all the organs).
That blood returns to the heart deoxygenated
Hearts
Fish
oxygen-depleted blood returns from the body enters the atrium, and then the ventricle, and is then pumped out to the gills where the blood is oxygenated, and then it continues through the rest of the body.
one atrium and one ventricle
2 Chambers
Single Circulation
Amphibians
three-chambered heart
two atria and one ventricle.
Double Circulation
Pumps for two circuts are combined into a single organ
Pulmonary circuit.. Right side of the heart pumps de-oxygenated blood into the capillary beds of the gas exchange tissues
Systemic circuit..left side of the heart pumps oxygen enriched blood from gas tissues to organs throughout body
Mammals
Double circualation
four very important blood vessels: the Vena Cava, the Pulmonary Artery, the Pulmonary Vein and the Aorta.
vena cava supplies de-oxygenated blood, which then flows into the right atrium then the right ventricle then gets pumped through the pulmonary artery to the lungs where it gets oxygenated, before returning to the heart via the pulmonary vein.
This flows through the left atrium into the left ventricle, and then gets pumped to the body via the aorta. Then returns to the heart through the vena cava,
Two atria, Two ventricle
Arteries
Veins
Capillaries
blood vessel that takes oxygenated blood from the heart to all parts of the body
two exceptions are the pulmonary and the umbilical arteries, which carry deoxygenated blood
blood vessels that carry blood toward the heart
veins carry deoxygenated blood from the tissues back to the heart
exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart
smallest blood vessels in the body
Diameter is only a bit greater than a red blood cell
Exchange of substances between the blood and interstitial fluid only occurs in the capillaries because the blood vessel wall are thin enough to permit exchange
Blood Pressure
Blood like most fluid flows from areas of higher pressure to areas of lower pressure
Contraction of the ventricle creates high pressure and exerts force in all directions
Regualtion
pressure in large arteries of the systemic circulation
Homeostatic mechanism regulate blood pressure by changing the diameter of arteriols
constriction raises pressure
Dilation lowers pressure
Lymph Circulation
Fluid that is forced out of the bloodstream during normal circulation is filtered through lymph nodes to remove bacteria
This fluid is then transported back into the bloodstream via the lymph vessels. Lymph only moves in one direction, toward the heart.
factors aiding lymph flow are breathing movements and muscular activity.
Lymph is formed from the tissue fluid that fills the interstitial spaces of the body. It is collected into lymph capillaries, that carry the lymph to the larger lymph vessels.
Functions
Blood
Connective tissue consisting if cells suspended in a matrix called plasma
Cells and cell fragments occupy about 45% of the volume of blood .. Remainder is plasma
In the plasma ions and proteins that function in osmotic regulation, transport and defense
Normal Values
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Red blood cell count
Male: 4.32-5.72 trillion cells/L
Female: 3.90-5.03 trillion cells/L
Hemoglobin
Male: 13.5-17.5 grams/dL*
Female: 12.0-15.5 grams/dL
Hematocrit
Male: 38.8-50.0 percent
Female: 34.9-44.5 percent
White blood cell count
3.5-10.5 billion cells/L
(3,500 to 10,500 cells/mcL)
Platelet count
150-450 billion/L
(150,000 to 450,000/mcL**)
- L = liter
Respiratory Organs
Gills
Outfoldings of the body surface suspended in water
Uses ventilation which is movement of gills over the respiratory medium (water)
Specialized structures
Worms have flattened appendages called parapodia that serve as gills but can also be used for crawling and swimming
Crayfish have special appendages that push water over the gills
The gills are composed of comb-like filaments, the gill lamellae, which help increase their surface area for oxygen exchange.
When a fish breathes, it draws in a mouthful of water at regular intervals.
Lungs
Localized respiratory organs subdivided into numerous pockets
trachea receives air from the pharynx and travels down to a place where it splits into a right and left bronchus. These supply air to the right and left lungs
supply air through alveolar ducts into the alveoli, where the exchange of gases take place.
The alveolar and pulmonary capillary gases balance across the thin blood–air barrier
Breathing is done by contraction of the diaphragm, and muscles pull the rib cage upwards. During breathing out the muscles relax, returning the lungs to their resting position.
Skin
A dense network of capillaries lies just below the skin, facilitating gas exchange between the external environment and the circulatory system.
respiratory surface must be kept moist in order for the gases to dissolve and diffuse across cell membranes
3 factors
Ventilation: the rate of delivery of respiratory medium (water or air) to the respiratory surface
Diffusion: the passage of gases through the skin
Convection: the carrying of dissolved gases towards or away from the lungs
Breathing
Muscles involved
Diaphram
Dome-shaped muscle that separates the abdominal cavity from the thoracic cavity
During inhalation, the diaphragm contracts, so that its center moves downward and its edges move upward
This expansion draws air into the lungs. When the diaphragm relaxes, elastic recoil of the thoracic wall causes the thoracic cavity to contract, forcing air out of the lungs
Intercostal muscles
muscles attached between the ribs manipulate the width of the rib cage.
three layers of intercostal muscles
external intercostal muscles are most significant in respiration. These have fibres that are pointed downward and forward from rib to rib The contraction of these fibres raises each rib toward the rib above, with the overall effect of raising the rib cage, assisting in breathing
Positive pressure breathing
Inflating lungs with forced air flow
Improved gas exchange, alters pulmonary mechanics, decreases work of the heart.
Amphibians
Negative pressure breathing
A breathing system in which air is pulled into the lungs.
using diaphram contraction mammals expand thoratic cavity to lower air pressure in lungs
Lowered air pressure causes air to rush through nostrils and mouth through the breathing tube to the aveoli
Osmoregulation and Excretion
Osmosis
molecules of a solvent pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, equalizing the concentrations on each side of the membrane.
Low to High
Freshwater animals
Have loss of ions (salt loss) from their body fluids to surroundings by diffusion
maintain osmosis balance and prevent salt loss by uptaking water and some ions in food and excrete urine with large amount of water and very little amount of ions
have the adaptation to prevent ion loss
ions move out of body
Marine animals
Osmoconformers, osmolarity is the same as the seawater
adapted to prevent water loss.
To avoid dehydration these creatures uptake large amount of sea water and expel salt in that water across their gills and skin
Nitrogenous waste
Ammonia
Urea
Uric acid
Invertebrates and acuatic species
Insects, birds, reptiles
Mammals, amphibians, some marine species
Excretory System
Kidneys
Ureter
Bladder
Urethra
Filter blood, remove waste products
holds urine until it is expelled from the body. The bladder receives urine through two ureters – one from each kidney
tube that carries urine from the bladder to the outside of the body
ducts that move urine from the kidneys to the urinary bladder
Nephron
distal tubule
collecting duct
capillaries
ascending lib of LOH
bowman's capsule
descending limb of LOH
picks up material pushed out of the glomerous
add toxins and drugs to proximal tubules pick up all the usefull things abosorbed out of the tubule
takes back water, salt and other drugs as needed
carries filterate to kidney pelvis, reaborbs water is told to by adh
salt is reabsrobed
water is reabsorbed
proximal tubule
useful things are reabsorbed into the blood