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CH 42 and 44 (42: Circulation and Gas Exchange (42.5 Gas exchange occurs…
CH 42 and 44
42: Circulation and Gas Exchange
42.2 Coordinated cycles of heart contraction drive double circulation in mammals
Mammalian Circulation: A Closer Look
Semilunar valves
located at the exit of the heart where aorta leaves the left ventricle and pulmonary artery leaves right ventricle
heart murmer
abnormal heart beat sounds
Atrioventricular (AV) valve
b/w each atrium and ventricle
Maintaining the Hearts Rhythmic beat
Electrocardiogram
ECK or EKG
currents recorded by electrodes placed on skin
Atrioventricular (AV) node
relay point for cells where impulses are delayed for 0.1 sec before spreading to the heart apex
connect through purkinje fibers
sinoatrial (SA node) or pacemakera
clusters of cells set timer
42.3 Patterns of blood pressure ad flow reflect the structure and arrangement of blood vessels
Regulation of Blood Pressure
vasoconstriction
when smooth muscle in arteriole walls contract, arterioles narrow
vasodilation
smooth muscle relaxed, arterioles undergo this process, an increase in diameter causing blood pressure in arterioles to drop
Blood Vessel Structure and Function
capillaries
smallest blood vessel, thing walls, consist of only endothelium and surrounding extracellular layer called basal lamina
Arteries and veins
2 layers of tissue surrounding the endothelium
outer layer is connective tissue with elastic fibers
inner layer is smooth muscle with elastic fibers
endothelium
single layer of flat epithelia cells that line the blood vessel cavity
arteries
thick and strong walls
elastic walls that can recoil to control blood flow
veins
thin walls
contain valves that maintain undirectional blood flow
Blood Pressure
ventricular contraction
Heart contraction generate blood pressure
measured as systolic pressure/diastolic pressure
systolic
highest blood pressure b/c heart contracts during ventricular systole
diastolic
elastic walls of arteries snap back, ventricles are relaxed
normal blood pressure is 120/70
pulse
rhythmic bulging of the artery walls with eachother
Fluid Return by the Lymphatic System
lymph
fluid lost by capillaries
lymph nodes
lymph filtering organs
lymphatic system
network of tiny vessels intermingled among capillaries
42.1 Circulatory systems link exchange surfaces with cells throughout the body
Gastrovascular cavities
functions in the distribution of substances throughout the body
hydras, jellies, cnidarians
facilitates exchange of gases and cellular waste
Circulatory systems
3 basic components
Interconnecting fluid
A muscular pump, the heart, that powers circulation
Circulatory fluid
Open Circulatory System
hemolymph
circulatory fluid (interstitial fluid)
percolates around organs, bathing cells
returns to the heart through short veins
leaves the heart through pores
Direct exchange b/w materials
Closed Circulatory System
blood
circulatory fluid
1 or more hearts pump blood into large vessels
large vessels to small vessels to organs
Annelids, cephalopods, and all vertebrates
High Blood pressue results in effective O2 and nutrients delivery
Organization of Vertebrate Circulatory Systems
Cardiovascular System
Closed Circulatory System for humans and some vertebrates
Blood circulates to and from the heart
3 main type of blood vessels
Arteries
carry blood away from the heart to organs
branch out into arterioles
carry blood to capillaries
Capillaries
microscopic, thin, porous walls
carry blood to venules
venules carry blood to veins
Veins
Carry blood back to the heart
portal veins carry blood b/w pairs of capillary beds
Muscular chambers
Atria
chambers that receive blood entering the heart
Ventricles
responsible for pumping blood out of the heart
Single Circulation
blood passing through heart once in each complete circuit through the body
found in boney fish, rays, sharks(2 heart chambers)
Double Circulation
2 pumps, 1 organ(heart)
1 pumps the right side
O2 goes into blood and CO2 goes out
Delivers O2 poor blood to capillary beds
Pulmonary circuit
Capillary beds are involved with the lungs
Reptiles
Pulmonocutaneous circuit
Capillary beds include both lungs and skin
Amphibians
1 pumps the left side
receive and pumps O2 rich blood
some are intermediate breathers
3 chamber heart
System Circuit
cycle of O2 and CO2 passing
42.4 Blood components function in exchange, transport, and defense
Blood Composition and Function
2 type of cells
Red Blood Cells
tranpost O2
biconcave shape
also known as Erythrocytes
lack mitochondria
generate ATP by anaerobic metabolism
White Blood Cells
also known as Leukocytes
fight infections
phagocytic
englulfing and digesting microorganisms
lymphocytes
develop into B and T cells
Stem Cells
replenish the body's blood cells populations
Red marrow bone produce blood cells
Plasma
liquid matrix where cells are in
plasma proteins act as buffers against pH change
makes up 55% of blood
Platelets
pinched off cytoplasmic fragments of specialized bonemarrow cells
serve as structural and molecular function in blood clotting
Erythropioetin (EPO)
hormone that stimulates the generation of more erythrocytes
increase O2 delivery results in decrease of EPO
42.5 Gas exchange occurs across specialized respiratory surfaces
Respiratory Surfaces
skin serves as respiratory organ in some amphibians and earthworms
other respiratory features such as gills, trachea, and lungs
O2 and CO2 moves across respiratory surfaces by diffusion
Gills in Aquatic animals
ventilation
movement of respiratory medium over the respiratory surafce
maintains partial pressure gradients of O2 and CO2
move gills to promote ventilation
countercurrent exchange
exchange of a substance or heat b/w two fluid flowing in opposite directions
Partial Pressure Gas Exchange
gas exhcange
uptake of molecular O2 to CO2
partial pressure
pressure exerted by a particular gas in a mixture of gases
atmospheric pressure at sea level, 760 mmHg
Trachea Systems in Insects
tracheal system
a network of airtubes branch throughout the body
diffusion through trachea in small insects bring enough O2
Mammalian Respiratory System
larynx
upper part of respiratory tract
passes air to trachea
trachea
windpipe
2 bronchi (singular and bronchioles)
alveoli
where gas exchange occurs
surfactant
mixture of phospholipids and proteins to reduce surface tension
Lungs
open circulatory system
all vertebrates that lack gills
localized respiratory organs
44: Osmoregulation and Excretion
44.4 The nephron is organized for stepwise processing of blood filtrate
From Blood Filtrate to Urine: A Closer Look
Descending limb of the loop of Henle
numerous water channels formed by aquaporin proteins make the transport epithelium freely permeable to water
This condition is met along the entire length of the descending limb
Ascending limb of the loop of Henle
The ascending limb has two specialized regions: a thin segment near the loop tip and a thick segment adjacent to the distal tubule
result of losing salt but not water, the filtrate becomes progressively more dilute as it moves up to the cortex in the ascending limb of the loop
The filtrate reaches the tip of the loop and then returns to the cortex in the ascending limb
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
Distal tubule
plays a key role in regulating the K+ and NaCl concentration of body fluids
involves variation in the amount of K+ secreted into the filtrate as well as the amount of NaCl reabsorbed from the filtrate
contributes to pH regulation by the controlled secretion of H+ and reabsorption of HCO3-.
Collecting duct
Final processing of the filtrate by the transport epithelium of the collecting duct forms the urine.
When the kidneys are conserving water, aquaporin channels in the collecting duct allow water molecules to cross the epithelium
The collecting duct carries the filtrate through the medulla to the renal pelvis
Solutes Gradients and Water Conservation
the production of hyperosmotic urine is possible only because considerable energy is expended for the active transport of solutes against concentration gradients
nephrons
particularly the loops of Henle
energy-consuming machines
produce an osmolarity gradient suitable for extracting water from the filtrate in the collecting duct
The mammalian kidney’s ability to conserve water is a key terrestrial adaptation
kidney can excrete urine up to four times as concentrated—about 1,200 mOsm/L
44.3 Diverse excretory systems are variatios on a tubular theme
Survey of Excretory Systems
Kidneys
functions in both osmoregulation and excretion.
consist of tubules
closely associated with a network of capillaries
typically nonsegmented, but there are exceptions
Metanephridia
most annelids, such as earthworms
excretory organs that collect fluid directly from the coelom
have both excretory and osmoregulatory functions
Protonephridia
flatworms
Phylum Platyhelminthes
form a network of dead-end tubule
found in rotifers, some annelids, mollusc larvaem and lancelets
Malpighian Tubules
insects and other terrestrial arthropods
remove nitrogenous wastes and that also function in osmoregulation
extend from dead-end tips immersed in hemolymph to openings into the digestive tract
Some terrestrial insects have an additional adaptation for water balance
The Mammalian Excretory System
Kidney Structure
renal cortex
supplied with blood and drained by renal vein
renal medulla
supplied with blood and drained by renal vein
renal pelvis
where urine is collected before it exits the ureter
Nephron Types
Cortical Nephrons
make of 85% of all the roughly 1 million nephrons
Juxtamedullary nephrons
essential for the production of urine that is hyperosmotic to body fluids
Nephrons
the functional units of the vertebrate kidney
Excretory Organs
kidneys
a pair of organs each about 10 cm in length, as well as organs for transporting and storing urine
ureter
A duct where urine exits from the kidney
Urinary bladder
a sac where the two ureters drain
urethra
A tube where urine is expelled from the bladder
Excretory Processes
filtration
driven by hydrostatic pressure
separation of solute and solvent in a solution
filtrate
a solution formed after the membrane has been crossed
water and small solute as salts, sugar, amino acids, and nitrogenous wastes
reabsorption
recovers useful molecules and water from the filtrate and returns them to the body fluid
Valuable solutes are reabsorbed by active transport
secretion
occurs by active transport
44.1 Osmoregulation balances the uptake and loss of water and solutes
Osmoregulatory Challenges and Mechanisms
osmoconformer
to be isoosmotic with its surroundings
all marine animals
osmoregulator
to control internal osmolarity independent of that of the external environment.
enables animals to live in environments that are uninhabitable for osmoconformers
freshwater and terrestrial habitats
Osmosis and Osmolarity
osmolarity
the number of moles of solute per liter of solutio
isoosmotic
Two solutions with the same osmolarity
hypoosmotic
more dilute solution
hyperosmotic
When two solutions differ in osmolarity, the solution with the higher concentration of solutes
Animals that live in temporary waters
anhydrobiosis
animals enter a dormant state when their habitats dry up, an adaptation
"life without water"
desiccation
extreme dehydration
tardigrades
waterbears
they contain about 85% water by weight
can dehydrate to less than 2% water and survive in an inactive state, dry as dust, for a decade or more
Land Animals
threat of dehydration is a major regulatory problem for terrestrial plants and animals
loose water through
urine
feces
skin
surfaces of gas exchange organs
desert animals
are well enough adapted for minimizing water loss
can survive for long periods of time without drinking.
44.2 Animals nitrogenous wastes reflect its phylogeny and habitat
Forms of Nitrogenous Waste
urea
in vertebrates, the product of a metabolic cycle that combines ammonia with carbon dioxide in the liver.
very low toxicity
high energy cost
ammonia
common in aquatic species
require lots of water access
uric acid
primary nitrogenous waste in insects, land snails, and many reptiles, and birds
nontoxic
more energetically expensive than urea
The Influence of Evolution and Environment on Nitrogenous Waste
soluble wastes can diffuse out of a shell-less amphibian egg or be carried away from a mammalian embryo by the mother’s blood
Using uric acid as a waste product
conveys a selective advantage
precipitates out of solution
can be stored within the egg as a harmless solid left behind when the animal hatches