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Circulation & Gas Exchange/ Osmoregulation & Excretion…
Circulation & Gas Exchange/ Osmoregulation & Excretion
Circulatory Systems
Open circulatory system
circulatory fluid called hemolymph is also the interstitial fluid that bathes body cells
EX: Arthropods- grasshoppers
EX: Molluscs- clams
Closed Circulatory System
circulatory fluid called blood is confined to vessels and is distinct from the interstitial fluid
one or more heart pumps blood into large vessels that branch into smaller ones that infiltrate the tissue and organs
EX: annelids, cephalopods, vertebrates
single circulation
blood travels through the body and returns to its starting point in a single circuit
animals consist of a 2 chambered; atrium and ventricle
double circulation
two circuits of blood flow
pumps for two circuits are combined into a single organ, the heart
one circuit- the right side of the heart pumps oxygen poor blood to the capillary beds of the gas exchange tissues where the net movement of O2 into the blood and of CO2 out of the blood
Cardiovascular System
describes the heart and blood vessels
Arteries
carry blood from the heart to organs throughout the body
Arterioles
arteries branch into arterioles
small vessels that convey blood to capillaries
Capillaries
microscopic vessels with very thin, porous walls
Capillary Beds
network of capillaries that infiltrate tissues passing within a few cell diameters of every cell in the body
Venules
capillaries converge into venules
Veins
venules converge into veins; the vessels that carry blood back to the heart
Blood Pressure
Blood like all fluids flow from areas of higher pressure to ares of lower pressure
contraction of a heart ventricle generates blood pressure which exerts a force in all directions
Systolic Pressure
arterial blood pressure is highest when the heart contracts during ventricular systole
Diastolic pressure
elastic walls of the arteries snap back
there is a lower but still substantial blood pressure when the ventricles are relaxed
before enough blood has flowed into the arterioles to completely relieve pressure in the arteries, the heart contracts again
Normal Blood pressure
120/70
Lymphatic System
the lost fluid and the proteins within it are recovered and returned to the blood
Lymph
circulates within the lympathic system before draining into a pair of large veins of the cardiovascular system completes the recovery of fluid lost from capillaries
Lymph Nodes
lymph vessels are small, lymph filtering organs
consist of a honeycomb of connective tissues with spaces filled by white blood cells which function in defense
Respiratory Surfaces
the movement of O2 and CO2 across respiratory surfaces takes place by diffusion
surfaces tend to be large and thin
skin
serves as a respiratory organ
a dense network of capillaries just below the skin facilitates the exchange of gases between the circulatory system and the enviornment
Gills
outfolding of the body surface that suspended in the water
octopuses & squids ventilate their gills by taking in and ejecting water
a current of water enters the mouth of the fish, passes through slits in the pharynx flows over the gills and then exits the body
Ventilation
maintains the partial pressure gradients of O2 and CO2 across the gill that are necessary for gas exchange
tracheal system
a network of air tubes that branch throughout the body
lungs
localized respiratory organs
representing an infolding of the body surface, they are typically subdivided into numerous pockets
alveoli
has exchange in mammals
breathing
the altering inhalation and exhalation of air
positive pressure breathing
inflating the lungs with forced air flow
begins when muscles lower the floor of an oral cavity drawing in air through the nostrils. next the nostrils and mouth closed the floor of the oral cavity rises forcing air down the trachea
negative pressure breathing
pulling, rather than pushing air into their lungs
using muscle contraction to actively expand the thoracic cavity, mammals lower air pressure in their lungs below that of the air outside their body
Osmoregulation
the process by which animals control solute concentration and balance water gain and loss
osmolarity
the number of moles of solute per liter of solution
Marine Animals
osmoconformers
to be isoosmotic with its surroundings
lose water by osmosis
internal salt concentrations much lower than that of seawater
salt tends to diffuse from the water into their bodies specially across their gills
urine removes some of the salt that diffuses into the body, the rest is lost in feces or is secreted from specialized glands
Freshwater animals
osmoregulatory problems
fluids must be hyperosmotic because animal cells cannot tolerate salt concentrations as low as that of lake or river water
osmolarity higher than that of their surroundings, they face the problem of gaining water by osmosis
water balance relies on excreting large amounts of very dilute urine and drinking almost no water
salt is lost by diffusion and in the urine are replenished by eating and by salt uptake across their gills
Nitrogenous Waste
animals excrete nitrogenous waste as ammonia, urea, or uric acid
ammonia
interconvert between NH3 and NH4
easily pass through membranes and are readily lost by diffussion to the surrounding water
released across the whole body surface
Urea
is the product of an energy consuming metabolic cycle that combines ammonia with carbon dioxide in the liver
very low toxicity
uric acid
nontoxic and does not readily dissolve in water
excreted as a semisolid paste with very little water loss
Excretory Organs & Nephrons types
Kidneys
a pair of organs each about 10 cm in lenght
transporting and storing urine
ureter
urine produced in the kidneys exit
Urinary Bladder
ureter drains into a common sac
urertha
urine is expelled from the bladder through a tube that empties to the outside near the vagina in females and through the penis in males
Nephrons
weaving back and forth across the renal cortex and medulla
Cortical nephons
reach only a short distance into the medulla
juxtamedullary nephrons
extend deep into the medulla and are essential for production of urine that is hyperosmotic to body fluids a key adaptation for water conservation in mammals