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CH's 42 and 44 (Circulation and Gas Exchange (Gas exchange occurs on…
CH's 42 and 44
Circulation and Gas Exchange
Circulatory systems have exchange surfaces throughout the body
Small molecules in and around cells undergo diffusion
diffusion is a very slow process
two types of exchange in animals
simple body plan (most/all cells are touching the outside environment)
Gastrovascular Cavity
cnidarians and planarians
openig on one end that connects to surrounding water
diffusion then occurs with the water in the surrounding environment
circulatory system
three basic parts
heart
circulatory fluids
vessels
in mammals, O2 must go through the lungs and then directly to the blood
can be open or closed
open
hemolymph bathes body cellls
Arthropods and molluscs
heart releases blood through pumps
blood goes into sinus and gas exchange occurs
heart contracts and blood is sucked back into the heart
closed
circulatory fluid = blood
confined to vessels
heart pumps blood into large vessels which pump blood into smaller ones that reach the tissues and organs
chemical exchange
Annelids, cephalopods, and vertebrates
both systems have evolutionary advantages
open systems use less energy
closed is good for larger animals
Organization of vertebrate circulatory systems AKA the cardiovascular system
Blood vessel types
Arteries - blood from heart to organs
Arterioles- link between arteries and capillaries
Capillaries- tiny vessels with porous surfaces, gas and chemical exchange occurs here
network of them = capillary bed
venules- capillaries empty blood here and blood is carried to veins
Veins- carry blood back to the heart
Heart contains chambers
Atria receives blood
Ventricle pushes blood out
Single Circulation
single circut
seen in many marine animals with gills
2 chambered heart
slower circulation
low blood pressure
Double circulation
2 circuits
amphibians, reptiles, and mammals
right side = O2 poor
pulmonary
left side = O2 rich
systemic
simplifies circulation coordination
high blood pressure
faster blood flow
There is double circulation in mammals
Mammalian Circulation
contraction of right ventricle pumps blood o the lungs via pulmonary arteries
blood goes through capillaries and loads O2 and unloads CO2
O2 rich blood goes to the left atrium
O2 rich blood flows into left ventricle
O2 rich blood leaves heart via aorta
arteries carry O2 rich blood to the rest of the body
once capillaries distribute blood, the rejoin and pour blood into the venules
Venules carry blood to the veins
veins carry O2 poor blood back to the right atrium
O2 poor blood is poured into the right ventricle
Mammalian Heart
behind the sternum
human heart = the size of a fist
made of mostly cardiac muscle
atria has thin wall and is used for blood collection
ventricles have thick walls and strong contractions (especially the left one)
cardiac cycle = sequence of pumping and filling the heart with blood
output is determined by 2 factors
heart rate
stroke volume
4 valves prevent backflow
Atrioventricular valves (between atrium and ventricle)
semilunar valves (at the exits of the heart
defective valve = heart murmur
Maintaining a beat
heart beats without signals from the nervous system
Sinoatrial node = a group of cells from which the heartbeat originates
sends out electrical signals that can be picked up be an EKG
Atrioventricular node = relay point that delays the cycle by about .1 seconds so the atria has time to empty itself
physiological signals can alter heartbeat
Blood pressure and flow reflects arrangement and structure of blood vessels
Vessel structure and function
blood vessels have a cavity lined with endothelium (a squamous epithelial layer)
it reduces resistance for blood flow
there are other layers wrapped around the endothelium
for capillaries
basal lamina
for arteries and veins
outer layer = connective tissues
stretchy enough to accommodate high pressure blood flow
inner layer = smooth muscle
regulates blood flow path
arteries have thicker walls but veins have valves
blood flow velocity
blood travels much slower in capillaries that arteries due to greater total cross-sectional area in the capillaries
Blood Pressure
contraction of the ventricle creates blood pressure
changes in pressure during the cardiac cycle
at its highest when the ventricle contracts
AKA systolic pressure
pulse occurs when your arterial walls bulge
when the arteries snap back into place a blood pressure is lower, it's known as diastolic pressure
regulation of blood pressure
vasoconstriction = increases pressure in the arteries
endothelin is a vasoconstrictor
vasodilation = decreases pressure in the arteries
Nitrogen oxide is vasodilator
blood pressure and gravity
blood pressure is significantly lower at locations higher than the heart
you faint when you don't have enough blood flow to brain to continue normal operations
capillary function
only 5-10% of capillaries are used at once
capillaries can control blood flow by using sphictors or constriction/dilation of arterioles
blood pressure pushes blood out and proteins pull blood back in
blood pressure is usually greater though
Lymphatic system
used to return lost fluids back to the blood
recovered fluid = lymph
lymph is much like veins in that there are valves and contractions
lymph nodes are filled with white blood cells
The functions of blood are to exchange, transport, and defend
Blood composition and function
plasma
a liquid matrix
55% of blood
function in transport, osmotic regulation,
ion concentration influences interstitial fluids
albumins act against pH changes
immunoglobulins fight against foreign substances
Apolipoproteins are lipid escorts
Fibrinogens clot blood
transports nutrients,waste, and respiratory gases
Cellular elements
Erythrocytes AKA: red blood cells
O2 transport
thin center and thicker outsides so that surface area is increased
don't have a nucleus so that there is room for hemoglobin
hemoglobin has iron in it to transport O2
each red blood cell has 250 million hemoglobin molecules
Leukocytes AKA: white blood cells
5 types of white blood cells
fights infection
can be phagocytic (cell eaters)
Platelets
fragments of bone marrow cells
clot the blood
Stem cells and cellular element replacement
cellular elements are developed from stem cells
stem cells can reproduce forever
one daughter is and stem cell and the other has a specialized function
stem cells are found in red marrow
Blood clotting
coagulation is the fancy way to put it
Fibrinogen is the inactive for of the coagulants
when you get an injury thrombin converts fibrinogen into fibrin
a big clot that blocks blood flow i called a thrombus
Cardiovascular disease
Atherosclerosis, heart attacks, and strokes
atherosclerosis is the hardening of arteries by fatty deposits
cholesterol is a key player in its development
LDL delivers cholesterol to cells
too much of this one increases risk of atherosclerosis
HDL returns the excess cholesterol to the liver
the beginning steps for a heart attack or stroke
Heart attacks
death of part of the cardiac muscle due to a blockage in the arteries
Strokes
lack of O2 to the brain
blockage of arteries in the brain that causes nervous tissue death
Risk factors and treatment
exercise and a diet low in trans fats can help
A high LDL/HDL ratio can be streated with medication
high blood pressure increases risk of a heart attack or stroke
Gas exchange occurs on specialized respiratory surfaces
Partial pressure gradients in gas exchange
partial pressure = pressure exerted by a particular gas in the mix of all the gasses
gas goes from higher pressure to lower pressure
respiratory media
air is easier to breathe and doesn't require efficient O2 absorption
water requires more energy for gas exchange
respiratory surfaces
where gas exchange occurs
always moist
diffusion is the process for gas exchange
large, thin, and made of epithelial tissue
skin can also be a respiratory organ
gills
body flaps that are suspended in water
ventilation = respiratory process
countercurrent exchange is the efficient process by which fish do gas exchange
Tracheal systems in insects
air tubes that branch throughout the body
Lungs
located in one spot
contains many pockets
mammals, reptiles, and birds rely entirely on this system
mammalian respiratory systems
lungs are located in the thoracic cavity
Larynx is the beginning of the trachea
nasal cavity is the beginning of the respiratory tract
the epiglottis keeps us from inhaling our food
trachea branches into 2 bronchi which branch into even smaller bronchioles
gas exchange occurs at the end of the bronchioles (alveoli)
mucus catches pollutants and cilia move mucus out of the lungs
Breathing ventilates the lungs
Amphibians
positive pressure breathing
they close mouth and nostrils to force air down the trachea
Birds
one way and one way out
two cycles to circulate air through the respiratory system
Mammals
negative pressure beathing
think of drawing medicine in a syringe
pulls air into the lungs
ribcage expands and diaphragm contracts during inhalation
during exhalation, everything relaxes
tidal volume = total air that's inhaled and exhaled in each breath
mammals don't empty their lungs completely in each breath
Breathing in humans
mostly involuntary
keeps the pH in blood normal (7.4)
One of the adaptations for gas exchange is the pigments that bind and transport gasses
Coordination of circulation and gas exchange
during inhalation, fresh air mixes with air inside the lungs
alveoli diffuse O2
when blood leaves the alveolar capillaries, it is oxygenated
O2 is delivered in the blood throughout the body and CO2 is picked up by the blood
blood goes back to the heart and lungs
CO2 is exhaled
Respiratory pigments
respiratory pigments = proteins that bind to O2 for more efficient breathing
very distinctive color
hemocyanin is blue
hemoglobin is red
polypeptide group and a heme group
CO2 transport
7% of CO2 is diffused from plasma and has a reaction with water
Osmoregulation and Excretion
Osmoregulation regulates intake and loss of water and solutes
Osmosis and osmolarity
osmolarity = moles of solute per liter of solution
isoosmotic= when 2 solution have the same osmolarity
hyperosmotic = high solute concentration
hypoosmotic = low solute concentration
Osomoregulatory Challenges and Mechanisms
Intro
Osmoconformer = to match the surroundings
no tendency to lose or gain water
all osmoconformers are marine animals
Osmoregulator = control of internal osmolarity despite external environment
typically live in freshwater and on dry land
Marine Animals
most marine invertebrates are osmoconformers
still transport solutes anyway
bony fish drink a lot of seawater to avoid water loss
need to maintain water
Freshwater Animals
opposite issues to marine animals
they need to maintain salts
drink almost no water and the urinate very dilute solutions
salmon can switch between environments due to their osmoregulatory mechanisms
Animals that live in temporary waters
sometimes water evaporates away
the animals living in that water don't die
they go into a dormant state called anhydrobiosis
anhydrobiosis = life without water
membranes stay intact by trehalose ( a sugar)
land animals
dehydration is eliminated by many adaptations
waxy cuticles in plants
exoskeletons
shells
keratinized skin cells
nocturnal
water is obtained via cellular respiration, drinking and eating
Energetics of Osmoregulation
active transport manipulates solutes
osmoregulation requires energy
minimizing the differences between internal and external environment save energy
Transport Epithelia
animals don't osmoregulate every cell but rather their internal body fluids
transport epithelia = specialized epithelial tissues that specialize in moving solutes
maintain water balance but also function in disposal of wastes
An animal's waste reveals its phylogeny and habitat
Ammonia
requires one to drink a lot of water
mostly aquatic animals
ammonia secretion occurs across entire surface of the bady
Urea
terrestrial and marine animals
low toxicity but high energy cost
Uric Acid
insects, land snails, and reptiles (including birds)
nontoxic and doesn't dissolve in water easily
very little water loss but high energy cost
The diverse excretory systems are all variations on a tubular theme
Excretory Processes
one excretory waste is urine
filtration occurs on a transport epithelia surface
filtrate is created
reabsorption absorbs the last of the useful molecules via active transport
secretion occurs when the nonessential solutes are left in the filtrate
excretion occurs when processed filtrate leaves the body
Survey of Excretory Systems
Protonephridia
protonephridia = network of deadend tubes that are open to the external environment that get rid of waste
most waste is eliminated out through the mouth or from several openings throughout the body
Metanephridia
mostly seen in annelids
large storage bladder that opens to the outside world
Malpighian Tubules
insects and arthropods
dead end tubule that receives waste from the hemolymph to excrete
conserves water very well
Kidneys
kidney = compact organ that filters blood
urine is produced here
nonsegmented
The nephron is organized for stepwise filtration of blood
Blood filtrate -> Urine
Proximal Tubule reabsorbs water, ions, and nutrients onto the interstitial fluid, and concentrates what's left of the filtrate
Henle descending loop reabsorbs even more water through its epithelial tissue that's only permeable to water via osmosis
Henle ascending loop thin segment allows NaCl to escape into the interstitial fluid. This causes the filtrate to become more dilute
Distal tubule secretes K+ and reabsorbs NaCl from the filtrate. Also does pH regulation
collection duct turns filtrate into urine, carries urine to the pelvis, and regulates how concentrated urine comes out to be
Solute Gradiants and Water Conservation
urine can be very concentrated compared to blood when an animal is trying to conserve water
concentration of urine in the mammalian kidney
filtrate starts of at about the same concentration as human blood
both water and salt is absorbed and therefore, volume decreases but osmolarity remains the same
counter current multiplier systems use energy to concentrate what becomes urine
kidney has the highest metabolic rate of all of the organs
concentration of urine minimizes water loss
desert mammals release the most concentrated urine
henle length depends on environment
Kidney function, water balance, and blood pressure are all linked by hormonal circuits
Homeostatic regulation of the kidney
Antidiuretic Hormone (ADH)
also called vasopressin
prevents high volumes of urine
activates aquaporin channles on the the surface of collecting duct cells
this causes a higher rate of water reabsorption
Renin-Angiotensin-Aldosterone (RAAS)
Aldosterone increases water and Na reabsorption
released when you have a major would or diarrhea
Renin makes angiotensin II, which causes vasoconstriction
Atrial Natriuretic Peptide (ANP) effect