Animal Form and function (chapter 44 osmoregulation and excretion…
Animal Form and function
chapter 42 Circulation and Gas Exchange
without a distinct circulatory system
exchange all cells in direct contact with the environment. diffusion
gastrovascular cavity functions in the distribution of substances throughout the body as well as in digestion.
circulatory system includes a circulatory fluid, a set of interconnecting vessels, and a muscular pump--heart
close circulatory system: one or more hearts pump blood into large vessels that branch into smaller ones that infiltrate the tissues and organs
circulatory fluid: blood
open circulatory system uses less energy than closed system
close circulatory system enable the effective delivery of oxygen and nutrients in larger and more active animals.
close circulatory system is useful to regulate the distribution of blood to different organs.
open circulatory system: heart pumps the hemolymph through the circulatory vessels into interconnected sinuses, spaces surrounding the organs.
the circulatory fluid:
the interstitial fluid that bathes body cells.
vertebrate circulatory system
capillary beds: infiltrate tissues, passing within a few cell diameters of every cell in the body.
capillaries: small vessels convey blood, microscopic vessels with very thin, porous walls.
veins:the vessels that carry blood back to the heart
venules:converge into veins
arteries: carry blood from the heart to organs through out the body
arterioles:arteries' branches in organs
artria: receive blood entering the heart
ventricles: pumping blood out of the heart
single circulation: one atrium, one ventricle
blood--atrium--ventricle (pump) --capillary beds in gills (O2+ and CO2-)--capillary --vessel (O2) --capillary beds in body (O2-,CO2+)--veins--heart
pulmonary circuit: the right side of the heart pumps blood (O2-) -- the capillary beds of gas exchange tissues -- oxygen into blood and CO2 out of blood
systemic circuit: the left side of the heart pump blood +O2 from gas exchange tissue to capillary beds -- exchange O2 and CO2, as well as nutrients and waste--O2- blood return to heart .
evolution in double circulation
natural selection and convergent evolution shaped the double circulation of bird and mammal.
three chambers (two atria and one ventricle)
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four chambers (two atria and two ventricle)
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pathway for blood: contraction the right ventricle --lungs via pulmonary arteries-- left and right lungs--loads O2 and unloads CO2--pulmonary veins--left atrium (oxygen-rich blood) -- left ventricl [pulmonary circus]
pathway for blood: left ventricle-- aorta--arteries-- (first branches leading from aorta are the coronary arteries which supply blood to the heart muscle itself)-- capillary beds in head and arms--diffusion of O2 to tissues and exchange CO2 in--venules--vein--superior vena cava.
pathway for blood: aorta--capillary beds in the abdominal organs and legs.-- diffusion of O2 to tissues and exchange CO2 in blood-- venules--vein-inferior vena cava.
have relatively thin walls and for blood returning to heart from body. blood enters the atria flows into ventricles while all four heart chamber relaxed.
have thicker walls and contract forcefully, especially left ventricle. two ventricles pump the same volume of blood.
atrioventricular valve (AV):
between each artrium and ventricle. blood returning from large veins flows into the atria and then into the ventricles through the AV valve
located at where the pulmonary artery leaves the right ventricle and where the aorta leaves the left ventricle. ventricular contraction pump blood into the large arteries through the semilunar valves
the contraction phase of the cycle
one complete sequence of pumping and filling
diastole: the relaxation phase
the volume of blood each ventricle pumps per minute
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heart murmur: blood squirts backward through a defective valve which may produce an abnormal sound; or the valves may be damaged by infection.
maintain heart's beat
sinoatrial (SA) node
: a group of autorhthmic cells,in the wall of the right atrium, near the superior vena cava enters the heart.
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atrioventricular (AV) node
: impulses are delayed for about 0.1 second before spreading to the heart apex. the delay allows the atria to empty completely before the ventricles contract.
sympathetic and parasympathetic: nervous system
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blood flow volocity
blood flow slows from arteries to arterioles to capillary. capillaries beds has big cross-sectional area.
blood flow speeds up returning the venules and veins because of smaller cross-sectional areas
structure: central lumen (cavity) lined with an endothelium, a single layer of flattened epithelial cell. smooth endothelial layer.
arteries and veins have walls with two layers of tissue surrounding the endothelium.
outer layer formed by connective tissue contains elastic fibers (vessel stretch and recoil), and collagen (strength)
arterial walls are thick, strong and elastic to maintain blood pressure and flow to capillaries
veins convey blood back to the heart at a lower pressure, no thick wall, contains valves to maintain a unidirectional blood flow
smallest blood vessels, very thin wall consists just endothelium and surrounded with
: extra cellular layer.
exchange substances between the blood and interstitial fluid
: low blood pressure when the ventricles are relaxed
high arterial blood pressure when heart contracts during ventricular systole
regulation: homeostatic mechanisms regulate arterial blood pressure.
the pressure produced by smooth muscles in arteriole walls contract, increased blood pressure upstream in the arteries.
smooth muscle relax, increasing diameter, cause blood pressure in the arteries to fall.
gravity affects blood pressure.
substances exchange between blood and interstitial fluid
small molecules diffusion across the endothelial cells
bulk flow of fluid into tissues driven by blood pressure
macromolecules are carried across the endothelium in vesicles (endocytosis), and release their contents on the opposite side (exocytosis)
the difference in osmotic pressure between the blood and the interstitial fluid opposes fluid movement out of the capillaries.
blood pressure tends to drive fluid out of the capillaries, the presence of blood proteins tends to pull fluid back.
the lost fluid and the proteins within it are recovered and returned to the blood via lymphatic system
located at the base of the neck
lymph: the recovered fluid, circulates within the lymphatic system before draining into large veins of the cardiovascular system
the transfer of lipids from the small intestine to the blood
completes the recovery of fluid lost from capillaries
lymph vessels have valves to prevent the backflow of fluid.
lymph nodes: small lymph-filtering organs, for body defense.
red blood cell: erythrocytes. mature mammalian erythrocytes lack nulcei-- benefits for hemoglobin to transport O2. lack mitochondria and generate their ATP exclusively by anaerobic metabolism.
platelets: has no nuclei. structural and molecular functions in blood clotting
white blood cell:leukocytes. some are phagocytic (engulfing and digesting microorganisms and debris), other called lymphocytes(against foreign substances)
plasma: dissolved in the plasma are ions and proteins, together with blood cells, function is osmotic regulation, transport and defense.much more concentration than intestitial fluid.
stem cells: can reproduce erythrocytes, leukocytes, and platelets. by two sets: 1. the lymphoid progenitor produce lymphocytes; 2. the myeloid progenitors produces all other white, red blood cells and platelets
if O2 level fall, kidneys synthesize and secrete a hormone called erythropoietin (EPO) to stimulate the generation of more erythrocytes
when injury eposes the protein in a broken blood vessel wall to blood constituents. the exposed proteins attract platelets and release clotting factors which trigger to form an active enzyme:
and an inactive form
. clots form blocking the flow of blood is
Heart attack: damage or death of cardiac muscle tissue resulting from blockage of one or more coronary arteries, which supply O2+ blood to the heart muscle.
stroke: death of nervous tissue in the brain due to a lack of O2.
the hardening of arteries by accumulation of fatty deposits. caused by abnormal level of cholesterol. individuals with a HIGH ratio of LDL to HDL are at substantially increased risk for atherosclerosis
LDL: low density lipoprotein: delivers cholesterol to cells for membrane production.
HDL: high density lipoprotein: scavenges excess cholesterol for return to the liver.
hypertension: an adult has a systolic pressure above 140mmHg or a diastolic pressure above 90mmHg.
respiratory system: gas exchange (uptake O2 from environment and discharge CO2 to environment
respiratory media: water is much more demanding gas exchange medium than air.
system in insects: a network of air tubes that branch throughout the body. the largest tubes called trachea,
open to outside
the efficient exchange of O2 and CO2 does not require the participation of the animal's open circulatory system
lungs: evolved both in open circulatory system and vertebrates
rely heavily on diffusion cross external body surface, like skin.
positive pressure breathing:
inflating the lung with forced air flow.
across moist epithelial surfaces continuous with their mouth or anus
mammalian: lungs are located in the thoracic cavity
mammal breath: negative pressure breathing: pulling, rather than pushing air into their lungs
diaphragm: skeleton muscle form bottom wall of cavity.
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during exercise, other muscles of the neck, back and chest increase the volume of thoracic cavity by raising the rib cage
larynx moves upward and tip the epiglottis over the glottis --open trachea enable breathing
trachea branches into two bronchi--one leads to each lung--branch into finer and finer tubes bronchioles
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the volume of air inhaled and exhaled with each breath.
the tidal volume during maximal inhalation and exhalation.
remains after a forced exhalation
control of breathing in humans
concentration of CO2 pH<7
during exercise, in creased breathing rate enhances O2 uptake and CO2 removal, with an increasing in cardiac output.
neurons in medulla oblongata
positive pressure breathing
second exhalation: as anterior air sacs contract, air that entered body at first inhalation is pushed out of body
firs inhalation: air fill the posterior air sacs
second inhalation: air passes through lungs and fills anterior air sacs
first exhalation: posterior air sacs contract, pushing air into lungs
have a total surface area much greater than that of the rest of the body's exterior
maintains the partial pressure gradients of O2 and CO2 across the gill for gas exchange
water--mouth--slits--pharynx--gill--exit the body
exchange of substance or heat between two fluids flowing in opposite directions.
blood enters a gill capillary, it encounters water that is completing its passage through the gill. O2--blood because the partial pressure gradient favors the diffusion of O2 from water to blood along the entire length of the capillary
coordination of circulation and gas exchange
blood leaves the lungs in the pulmonary veins, returning to the heart, blood is pumped through the systemic circuit.
in systemic capillaries, gradients of partial pressure favor the net diffusion of O2 out of the blood and CO2 into the blood
net diffusion O2 down its partial pressure gradient from the air in the alveoli to the blood. net diffusion of CO2 from blood to air.
with loaded CO2, blood returns to the heart and pumped to the lungs again
inhalation, fresh air mixes with air remaining in the lungs
exchange in the alveolar capillaries, exhaled air enriched in CO2 and partially depleted of O2
: protein bound with O2. respiratory pigment circulate with the blood or hemolymph.
with a few exception, these molecules have a distinctive color and consist of a metal bound to a protein.
the respiratory pigment of many invertebrates and almost all vertebrates is hemoglobin.
hemolglobin binds O2 reversibly, loading O2 in the lungs or gills and unloading it elsewhere in body.
low pH decreased the affinity of hemoglobin for O2.
diving mammals contain a high concentration of an O2 storing protein called
in their muscles.
genetic changes increased traits such as blood volume and myoglobin concentration who'll have improved diving ability.
large and thin surface
earthworm and amphibians use skin as a respiratory organ
contact with aqueous solution
partial pressure gradients: gas undergoes net diffusion from a region of higher pressure to lower pressure
chapter 44 osmoregulation and excretion
animals control solute concentration and balance water gain and loss
water enters and leaves cell by different solute concentration. unit of measurement for solute concentration:
hyperosmotic: higher solute concentration, lower free water concentration
hypoosmotic: lower solute concentration, higher free water concentration
isoosmotic: two solutions have the same osmolarity.
mechanisms to maintain water balance
osmoconformer: to be isoosmotic with its surroundings. all osmoconformers are marine animal
marine animal: most marine invertebrates are osmoconformers.
actively transport specific solutes in hemolymph different from those in the ocean
balance water loss by drinking a lot of seawater and eliminate excess salts through the gills and kindeys
eliminate nitrogenous waste products
shark internal salt concentration is much lower than that of seawater.
TMAO(trimethylamine oxide) protects proteins from the denaturing effect of urea, and osmoregulation. TMAO with salt, urea and other compounds make water enters sharks body slowly.
urine also removes some of the salt.
osmoregulator: internal osmolarity independent of that of the external environment.
internal fluids have higher osmolarity than surroundings-- gaining water by osmosis
water balance by large amounts of dilute urine.
salt lost by diffusion and in the urine, replenished by eating and salt uptake by gills
animals living in temporary waters
anhydrobiosis: life without water
lose water in urine and feces, skin, and surface of gas exchange organs.
maintain water balance by drinking and eating moist foods and cellular respiration.
stenohaline and euryhaline
stenohaline: cannot tolerate substantial changes in external osmolarity
euryhaline: survive large fluctuation in external osmolarity
energy and transport epithelia for osmoregulation
energy cost depends on different osmolarity between animal and surroundings, water and solutes move across the animal's surface, and work needed to pump solutes across the membrane.
osmoregulation and metabolic waste disposal rely on
--one or more layers of epithelial cells for moving particular solutes in specific direction.
marine bird uses a transport epithelium of nasal gland to move salt from the blood into secretory tubules, which drain into central ducts leading to the nostrils
process of ridding the body of nitrogenous metabolites and other metabolic waste products
excretory process: figure 44.3
filtrate from blood--
the excretory tubule
. water and solutes--across the selectively permeable membranes of capillaries by force of blood pressure--
the excretory tubule.
transport epithelium reclaims valuable substances from filtrate and returns them to the body fluids.
toxins and excess ions are extracted from body fluids --
excretion: the altered filtrate (urine) leaves the system and the body
excretory organs collect fluid directly from the coelom. serve both an excretory and an osmoregulatory function. e.g. earth warm.
water balance by dilute urine.
transport epithelium reabsorbs most solutes and returns them to the blood in the capillary.
remove nitrogenous wastes and function in osmoregulation. e.g. insects and terrestrial arthropods.
transport epithelium secretes certain solutes including nitrogenous wastes
as fluid passes the tubules into rectum, most solutes are pumped back into hemolymph
mainly insoluble uric acid are eliminated as nearly dry matter along with the feces
water follows the solutes into the tubule by osmosis. water reabsorption by osmosis follows
serve chiefly in osmoregulation. most metabolic wastes diffuse out across the body surface or excreted into the gastrovacular cavity and eliminated through the mouth. e.g. flatwarm
drawn by beating cilia, interstitial fluid filters through the membrane where the cap cell and tubule cell inter lock.
filtrate empties into the external environment
kidneys: functions in both osmoregulation and excretion. consists of tubules.
structure figure: 44.12
enlarged upper end of the ureter, the tube through which urine flows from the kidney to the urinary bladder
outer renal cortex and inner renal medullar:
are supplied with blood by a renal artery and drained by a renal vein. all filtrate is reabsorbed into the surrounding blood vessels and exits the kidney in the renal vein.
functional units of the vertebrate kidney
juxtamedullary nephrons: extend deep into the medulla. essential for production of urine that is hyperosmotic to body fluids. for water conservation in mammal.
cortical nephrons: reach only a short distance into the medulla
Bowman's capsule: surrounds the glomerulus. filtrates moves from blood into glomerulus into the lumen of Bowman's capsule
major regions of the nephron
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glomerulus: a ball of capillaries
collection duct: receives processed filtrate from many nephrons and transports it to the renal pelvis
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peritubular capillaries: surround the proximal and distal tubules
vasa recta: hairpin-shaped capillaries that serve the renal medulla, including the long loop of Henle of juxtamedullary nephrons.
blood supplied to nephrons by afferent arteriole. the capillaries converge as they leave the glomerulus, forming an efferent arteriole.
concentration urine : figure 44.14
countercurrent mutiplier system
countercurrent system of the loop of Henle involves active transport and expenses energy.
birds and reptiles: adapting to dehydrating
birds: having uric acid as the nitrogenous waste molecules.
reptile:only have cortical nephrons and produce urine that is isosmotic or hypoosmotic to body fluid.
freshwater fish and amphibians
produce very dilute water. salt conservation relies on teh reabsorption of ion from the filtrate int eh distal tubule. adapting
amphibians: in freshwater excrete dilute urine, and skin accumulates salts by active transport. on land, reabsorbing water across the epithelium of the urinary bladder.
adapting hypoosmotic in water and dehydration on land
producing small quantities of highly concentrated urine. adapting to an unusual food source
marine bony fishes: adapting seawater with divalent ions
get rid of divalent ions by secreting them into proximal tubules of the nephrons and excreting them in urine.have fewer or smaller nephrons and nephrons lack a distal tubule . small or no glomeruli. filtration rates are low.
homeostatic regulation of kidney: a combination of nervous and hormonal controls manages the osmoregulatory function of mammalian kidney
antidiuretic hormone (ADH):
released from the posterior pituitary bind to and activate membrane receptors on the surface of collecting duct cells
control of collecting duct permeability: figure:44.18
vesicles with aquaporin water channels are inserted into membrane lining lumen of collection duct
ADH binds to membrane receptor
aquaporin channels enhance reabsorption of water from collecting duct into interstitial fluid.
receptor triggers signal transductions
regulate fluid retention in the kidney:
blood osmolarity increases
osmoreceptors trigger a release of ADH from the posterior pituitary and generate thirsty.
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RAAS (renin-angiotensin-aldosterone system
): figure 44.21
responds to the drop in blood volume and pressure by increasing water and Na ion reabsorption
involves juxtaglomerular apparatus (JGA) which release ezyme renin ultimately yielding peptide
angiotensin II stimulats the adrenal glands
aldosterone causes the distal tubules and collecting duct to reabsorbe Na ion and water to increase blood volume and pressure.
ANP (atrial natriuretic peptide) opposes the RAAS.
the walls of the atria of the heart release ANP in response to an increasing in blood volume and pressure
ANP inhibits the release of renin from JGA, inhibits NaCl reabsorption by the collecting ducts, and reduces aldosterone release.
neurons in the hypothalamus dedicated to regulating thirst.
excreted as a semisolid pate with very little water loss. more energy cost than urea.
insects, land snails, many reptiles including birds
needs a lot of water to excrete. diffusion to surrounding water.
Many invertebrates release ammonia across the whole body surface.
combines ammonia with carbon dioxide in liver. energy cost
most terrestrial animals and many marine species
evolution and environment impact nitrogen wastes excretion
the type and amount of nitrogenous waste a species produces are matched to its environment
e.g. amphibian eggs lack a shell, ammonia or urea can diffuse out of the egg.
endotherms produce more nitrogenous waste than ectotherm. predators eat protein, excrete more nitrogen than animal eats lipids or carbohydrates.
human excretory organs:
ureter:a duct for urine to exit
urinary bladder: sac for two ureters drain into
kidneys: transporting and storing urine
urethra: empties to the outside near the vagina in females and through the penis in males
two venae cavae empty their blood into the right atrium and O2- blood flows into the right ventricle