Please enable JavaScript.
Coggle requires JavaScript to display documents.
Circulation, Gas Exchange, Osmoregulation, & Excretion (Ch. 42:…
Circulation, Gas Exchange, Osmoregulation, & Excretion
Ch. 42: Circulation & Gas Exchange
Circulatory Systems
open/closed
3 components: circulatory fluid, set of interconnecting vessels, and muscular pump (heart)
open: hemolymph (circulatory fluid) is also interstitial fluid
arthropods, some molluscs
closed: blood is confined to vessels and is distinct from interstitial fluid
mammals, annelids, cephalopods, all vertebrates
vertebrate circulatory systems
cardiovascular system: heart and blood vessels
main types of blood vessels in which blood flows in one direction only: arteries, veins, capillaries
arteries: carry blood from heart to organs
arterioles: branches of arteries
capillaries: microscopic vessels with thin, porous walls
capillary beds: networks of capillaries that infiltrate tissues
dissolved gases and other chemicals are exchanged by diffusion between blood and interstitial fluid
downstream end where blood flows back to heart
venules: after capillaries
veins: carry blood back to heart
heart
atria: two chambers of heart that receive blood
ventricles: two chambers that pump blood out of heart
single circulation
blood travels through body and returns to starting point in a single loop
sharks, rays, and bony fish
heart has 2 chambers
double circulation
2 loops of blood flow: to lungs, heart, body, and back to heart
amphibians, reptiles, mammals
4 heart chambers in mammals
3 heart chambers in frogs and reptiles
Heart Contraction
mammalian circulation
1) right ventricle contracts
2) semilunar valve to pulmonary arteries
3) blood flows through capillary beds around alveoli and returns to heart through pulmonary veins
4) left atrium
5) left ventricle contracts
6) O2-rich blood flows through aorta
7) arteries and arterioles lead to capillary beds in head and arms
8) capillary beds in abdomen and legs (O2 in blood leaves and CO2 diffuses into it)
9) O2-poor blood from head, neck, and forelimbs flows through superior vena cava
10) O2-poor blood from trunk and hind limbs flows into inferior vena cava
11) 2 vena cavas empty blood into right atrium and then into left ventricle
cardiac cycle: one complete sequence of pumping and filling
systole: contraction phase
diastole: relaxation phase
cardiac output: volume of blood each ventricle pumps per minute
heart rate: rate of contraction (# of beats per minute)
average is 72 bpm
stroke volume: amount of blood pumped by a ventricle in a single contraction
average is 70mL
average cardiac output is 5 L/min. (about total amount of blood in human body)
heart valves
AV valve: atrioventricular valve lies between each atrium and ventricle
pressure exerted when ventricle contracts keeps AV valve closed
semilunar valves: where blood exits each ventricle to go into pulmonary arteries or aorta
open when ventricle contracts and close when ventricles relax so no blood flows back through
heart murmur: abnormal sound in heart when blood squirts backward through defective valve
heart rhythm
sinoatrial (SA) node: cluster of cells (pacemaker)
sets the rate and timing at which at which all cardiac muscles contract by producing electrical impulses
EKG (electrocardiogram): electrodes on skin record currents, measuring electrical activity of heart
atrioventricular (AV) node: delays impulses for .1 secs. before spreading to heart apex
bundle branches and Purkinje fibers: send signals from AV node to heart apex
Blood Pressure
Blood Vessels
all contain a single layer of simple squamous epithelium, which minimizes resistance to fluid flow
capillaries
smallest blood vessels with diameter size of red blood cell
endothelium layer is thin enough to allow exchange of gases and chemicals
arteries
walls are think, strong, and elastic to accommodate blood being pumped out of heart
endothelium layer is small in diameter, smooth muscle layer and connective tissue layer are thick
veins
convey blood back to heart and lower pressure, so they don't have thick walls
endothelium layer is wide, smooth muscle and connective tissue layers are thin
contain valves to keep low pressure blood flowing in one direction
Blood Pressure
blood flows from areas of high pressure to lower pressure
systolic pressure: arterial blood pressure is highest when heart contracts during ventricular systole
each contraction causes spike in blood pressure that stretches walls of arteries
pulse: rhythmic bulging of artery walls with each heartbeat
diastolic pressure: elastic walls of arteries snap back during diastole, and lower blood pressure when ventricles are relaxed
how to measure
healthy blood pressure is 120 mm of mercury (Hg)/70 mm Hg
systolic pressure/diastolic pressure
can drop/rise depending on gravity throughout the day
lymphatic system
every day we lose 4-8 L of fluid from capillaries to surrounding tissues
blood pressure in capillaries forces fluid to leak out
lymphatic system returns lost fluid (lymph) to blood
lymph nodes: organs in lymph vessels that filter lymph
contain white blood cells
during infection, white blood cells multiply and lymph nodes become swollen
fluid travels along lymph vessels around body until being dumped into veins in neck
Blood
composition
plasma: liquid extracellular matrix of blood cells
contains water, ions, proteins, and substances transported by blood (like nutrients, nutrients, and hormones)
45% of blood is cells and platelets, the rest is plasma
platelets:cell fragments involved in clotting that are suspended in plasma
thrombus: blood clot within a blood vessel, blocks flow of blood
erythrocytes: red blood cells
most numerous and last 120 days
transport O2
shaped like little disks, thinner in center bc no nucleus
have hemoglobin (protein that contains iron and transports O2)
sickle-cell disease: results from faulty amino acid sequence of hemoglobin
sickled cells get stuck in arteries and arterioles, preventing delivery of O2
leukocytes
there's 5 types of white blood cells
fight infections by phagocytosis or mount immune responses (lymphocytes) against foreign antigens
also found outside circulatory system, patrolling interstitial fluid and lymphatic system
stem cell: replenish body's blood cells
found in bone marrow, make red and white blood cells and platelets
when it reproduces by mitosis, one daughter cell stays a stem cell while the other adopts a function
more red blood cells are made every time level of O2 falls
cardiovascular disease
atherosclerosis:hardening of arteries by accumulation of fatty deposits
caused by damage or infection that roughens smooth inner lining of arteries, which reduces blood flow
1) leads to inflammation: leukocytes accumulate in injured area
2) leukocytes attract lipids (cholesterol), and plaque (fatty deposit) grows
3) walls of artery become thick and stiff, and thrombus forms if plaque ruptures, which can trigger heart attack or stroke
LDL: low-density lipoprotein delivers cholesterol to cells for membrane production; makes plaque worse
HDL: high-density lipoprotein gets rid of excess cholesterol
increases blood pressure (BAD)
heart attack: myocardial infarction, damage/death of cardiac muscle tissue bc of blocked coronary arteries
coronary arteries supply O2 to heart
heart can stop beating (cardiac arrest) if severe enough, even death
stroke: death of nervous tissue in brain due to lack of O2
bc of rupture or blockage of arteries in head
level of damage depends on what part of brain stroke occurred in
hypertension: high blood pressure
can lead to stroke/heart attack
damages endothelium of arteries, which leads to plaque
140/90 or higher
can be controlled by diet, exercise, medication
Gas Exchange
partial pressure
pressure exerted by a particular gas in a mixture of gases
a gas always diffuses from a region of higher partial pressure to region of lower partial pressure
21% of Earth's atmosphere is O2
uptake of O2 from environment and discharging CO2
how animals breathe
O2 diffusion through skin
sponges, cnidarians, flatworms, earthworms, amphibians
done by simple animals
skin is made up of thin, moist epithelium
body is close enough to the ground for exchange of gases through skin
gills in aquatic animals
outfoldings of body surface suspended in water
use ventilation (water moving over gills) to maintain partial pressure of necessary O2 and CO2
crayfish/lobsters, mussels, octopi, squids, fish
countercurrent exchange: blood in gills and water flow in opposite directions, so blood gets a lot of O2
efficient: 80% of O2 is taken in through gills
tracheal system in insects
network of air tubes that branch throughout body
largest tubes are tracheae and open to outside environment
air sacs are formed from portions of tracheae near organs that need more O2
insects need more O2 when flying
lungs
stay in one place, not like insect tracheae that are all throughout body
circulatory system transports gases from lungs to rest of body
spiders, land snails, vertebrates
nose/mouth, pharynx, larynx, trachea, thoracic cavity (bronchi, bronchioles, alveoli)
cilia in trachea, bronchi, and bronchioles move contaminants up into pharynx to be swallowed
alveoli protected by surfactant, but have thin endothelium so they can be damaged by cigarette smoke and coal dust
Breathing & Adaptations for Gas Exchange
breathing: process that ventilates lungs; inhalation and exhalation of air
positive pressure breathing
inflating lungs with forced air flow
1) oral cavity muscles lower (air moves in through nostrils)
2) nostrils and mouth close, floor off oral cavity rises and air is pushed down into lungs
3) air is expelled when lungs and muscular body wall contract
pressure is added to air as it is squeezed down
how mammal breathes
negative pressure breathing
pulling air into lungs (instead of pushing)
gas flows from higher to lower pressure
1) inhalation: diaphragm contracts and moves down, ribs expand and move up, lungs inflate
2) exhalation: diaphragm relaxes and moves down, ribs move down and get small, lungs deflate
tidal volume: volume of air inhaled and exhaled with each breath (about 500mL in humans)
vital capacity: tidal volume during max inhalation and exhalation (about 3.4L-4.8L in humans
residual volume: the air that remains after a forced exhalation
homeostatic control of breathing in humans
1) blood pH falls bc of rising levels of CO2 (during exercise)
2) sensors in major blood vessels detect decrease in blood pH
normal blood pH is about 7.4
3) medulla detects decrease in pH of cerebrospinal fluid
4) signals from medulla to rib muscles and diaphragm increase rate and depth of ventilation
5) blood CO2 level falls and pH rises
respiratory pigments: circulate blood/hemolymph and are contained within blood cells
animals transport O2 around body with these proteins
hemoglobin: within erythrocytes
each has 4 heme groups (cofactors that make hemoglobin work) and 4 iron atoms
heme groups are red
iron atom binds to one molecule of O2
Bohr shift: when hemoglobin can't pick up O2 bc of low pH (more acidic) in blood (caused by high levels of CO2 and more H+)
Ch. 44: Osmoregulation & Excretion
Diverse Excretory Systems
excretion: process in which nitrogenous metabolites and metabolic waste products are expulsed from body
excretory processes
1) filtration: excretory tubule collects filtrate from blood (blood pressure forces water and solutes out of capillaries)
2) selective reabsorption: substances move out of filtrate and return to body fluids
3) selective secretion: other substances (like toxins and excess ions) are added to filtrate
4) selective excretion: processed filtrate leaves body as urine
excretory systems
protonephridia
flatworms (lack coelom)
network of dead-end tubules that branch throughout body
1) interstitial filters into tubule by beating cilia
2) filtrate exits body
beneficial to get rid of excess water
metanephridia
earthworms
excretory organs that collect fluid directly from coelom
1) coelomic fluid is drawn into tubule by beating cilia
2) most solutes in filtrate are reabsorbed into blood through capillaries
3) filtrate is mostly water that goes into collecting tubule, bladder, and then exits
Malpighian Tubules
insects and other terrestrial arthropods
attached to digestive tract; urine is mixed directly with feces
no filtration step
effectively conserves water
kidneys
tubules in kidneys are highly organized and intertwined in a network of capillaries
vertebrates
urine leaves kidneys and goes to ureters, drains into bladder, and is expelled through urethra
renal cortex: outer layer of kidney
renal medulla: inner part of kidney
renal pelvis: center of kidney where urine accumulates (exits collecting duct from each nephron) before exiting through ureters
kidney is made up of nephrons (weave back and forth across cortex and medulla)
each human kidney contains about 1 million nephrons
85% are cortical nephrons: reach short distance into medulla
15% are juxtamedullary nephrons: extend deep into medulla
juxtamedullary nephrons allow for urine to collect more solutes (hyperosmotic to body fluids)
Nephron
consists of a single long tubule with:
glomerulus: ball of capillaries surrounded by Bowman's capsule
proximal tubule
loop of Henle: hairpin turn with a descending and ascending limb
distal tubule
collecting duct: receives processed urine from many nephrons and transports it to renal pelvis
peritubular capillaries: surround proximal and distal tubules
vasa recta: hairpin-shaped capillaries that surround loop of Henle
blood filtrate to urine
1) filtrate is formed when blood pressure forces fluid from blood in glomerulus to lumen of Bowman's capsule
2) reabsorption of salt and nutrients in proximal tubule
3) diffusion of water in descending limb of loop of Henle
4) passive/active transport of salt in ascending loop of Henle
5) reabsorption in distal tubule
6) last reabsorption in collecting duct before urine exits into renal pelvis
kidney adaptations in diverse environments
vampire bat: excretes large amounts of dilute urine while feeding on a lot of blood so it won't be too heavy to fly
birds/reptiles: live in dry areas, so nephrons have shorter loops of Henle to lose less water and excrete more concentrated urine
freshwater fish and amphibians: produce very dilute urine
marine bony fish: have fewer and smaller nephrons and lack distal tubule, so very little urine is excreted (conserves water)
Nitrogenous Wastes
ammonia
when proteins and nucleic acids are broken apart for energy or converted to carbs/fats, enzymes remove nitrogen in the form of ammonia; very toxic
most aquatic animals (most bony fish)
must be excreted into water bc ammonia can only be tolerated at very low concentrations
ammonia release occurs across whole body surface
urea
mammals, most amphibians, sharks, and some bony fish
excreted by animals that don't have access to water
nitrogenous waste that is the product of energy-consuming metabolic cycle that combines ammonia with CO2 in liver
takes more energy to produce urea than to produce ammonia
low toxicity
uric acid
nontoxic and insoluble in water
insects, land snails, reptiles (birds)
bird droppings (guano) are mixture of white uric acid and brown feces
excreted as semisolid paste with little water loss
needs more energy than urea and ammonia
Hormonal Circuits
system of checks and balances that regulate kidney's ability to control blood osmolarity, salt concentration, volume, and pressure
antidiuretic hormone (ADH)
AKA vasopressin
released from posterior pituitary gland
reduces urine volume to preserve water and lowers blood osmolarity back to set point
high level of urine production is called diuresis
happens when blood osmolarity rises (when you ingest too much salt or lose water through sweating)
makes you pee more so the amount of water in body can be the same as the amount of solutes (we don't want this so ADH is released to fix it)
renin-angiotensin-aldosterone system (RAAS)
atrial natriuretic peptide (ANP)
opposes RAAS
walls of atria in heart release ANP in response to increase in blood volume and pressure caused by RAAS
renin release stops, salt reabsorption stops, aldosterone release stops
released when there's an excessive loss of salt and water (bc of severe wound or diarrhea); reduces blood volume with increasing osmolarity
RAAS increases water and Na+ reabsorption
negative feedback circuit
renin (enzyme) release is triggered by drop in blood pressure and blood volume
angiotensin II and aldosterone are released, which causes a rise in blood pressure and volume, which reduces release of renin
Osmoregulation
process by which animals control solute concentrations and balance water gain/loss
osmolarity: unit of measurement for solute concentration; # of moles per liter of solution
osmolarity of human blood is 300 mOsm/L, and of seawater is 1000mOsm/L
isoosmotic: 2 solutions with same osmolarity
hyperosmotic: solution with higher concentration of solutes
hypoosmotic: more dilute solution into which water wants to flow
osmoregularity challenges and mechanisms
osmoconformer: animal that is isoosmotic with its surroundings
marine animals live in water that has stable composition, so there's no need to gain/lose water
drink a lot of seawater, pee out a lot water and excrete excess salts
osmoregulator: animal that controls internal osmolarity
freshwater
problems of freshwater fish are opposite of marine fish
need more salts in their bodies than are in the water
drink little water, pee very dilute urine
terrestrial
try to fight dehydration by losing as little water as possible
drink and eat moist foods and produce water during cell resp.
discharges excess water in hypo, takes in more water in hyper
internal osmolarity is diff. than environment
tardigrades
practice anhydrobiosis: enter dormant stage whenever water isn't available in their environment
can live with 2% water in their body (shrivel up until they're rehydrated)
transport epithelia: one or more layers of epithelial cells specialized for moving particular solutes in controlled amounts in specific directions
helps marine birds survive on seawater bc they have nasal glands that secrete excess salts down their beaks