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Animal Systems (Circulation and Gas Exchange (Specialized Respiratory…
Animal Systems
Circulation and Gas Exchange
Exchange Surfaces
Gastrovascular Cavities
In phylum cnidaria
Has an opening at one end to connect cavity to water
Fluid on the inside and outside, gas exchange
Open/Closed Circulatory Systems
3 Basic Components
: Circulatory fluid, interconnecting vessels, muscular pump (heart)
Heart increases pressure on vessels
Transports fluid throughout body
Connects water environment of cells to organs
Open Circulatory System
circulatory fluid is interstitial fluid (hemolymph)
In arthropods, and some molluscs
Heart pumps hemolymph through vessels to sinuses
In sinuses, gas exchange occurs
Heart relaxes, hemolymph goes back in
Closed Circulatory System
circulatory fluid (blood) is different from interstitial fluid
Heart pumps blood to large vessels that branch to smaller ones that infiltrate tissue + organs
Chemical exch. between blood + interstitial fluid
Annelids, cephalopods, and vertebrae
Open uses less energy
Closed brings more O2 to big animals
Organization
Single Circulation
blood travels in loop
Heart w/ 2 chambers
Blood enters through atrium goes to ventricle then capillary bed in gills
When blood leaves, capillaries merge to vessel
Blood enters veins and goes back to heart
Blood leaving goes through 2 capillary beds
Double Circulation
2 circuits of blood flow
Pulmonary/Pulmocutaneous Circuit
: Right side of heart pumps blood to capillary bed (O2 in, CO2 out)
Systemic Circuit
: Left side of heart pumps O2 rich blood from gas exch. tissue to capillary bed in organs and tissues
Gas exch. occurs then O2 poor blood goes back to heart
Lots of blood flow to major organs
Variation in Double
Amphibians and Reptiles do gas exch. periodically not all the time
Frogs shut off blood flow to lungs when underwater but continues to skin
Endotherms need more energy that double circulation allows for
Heart Contraction
Mammalian Circulation
Right ventricle contracts + pumps blood to lungs using pulmonary arteries
As it flows through left/right lungs, loads O2 and unloads CO2
Returns from lungs through pulmonary veins to left atrium
Into left ventricle, pumps out to body tissues
Coronary arteries supply blood to heart itself
Then go to capillary beds ini head and arms
Then organs and legs
O2 poor blood from head/forelimbs goes to superior vena cava
O2 poor blood from trunk, hind limbs goes to inferior vena cava
2 vena cava empty blood to right atrium, then goes to right ventricle
Blood flows in and out at the same time
Mammalian Heart
Size of clenched fist
Made of cardiac muscle
Cardiac Cycle
: 1 sequence of pumping and filling
Systole
: Contraction phase
Diastole
: Relaxation phase
Cardiac Output
: Volume each ventricle pumps a min.
Heart Rate
: Rate of contraction
Stroke Volume
: Amt of blood pumped by ventricle a min.
Avg. stroke in humans is 70 mL, avg. cardiac output of 5 L/min.
Valves in the heart prevent backflow
Valves open when pushed from one side and close when pushed from other
Atrioventricular Valve
: between atrium and ventricle
Pressure from contraction of ventricles closes AV valve, no blood into atria
Semilunar valves
: 2 exits (pulmonary artery leaves right ventricle, aorta leaves left ventricle)
Valves open by pressure during contraction
When ventricles relax, pressure ini pulmonary artery and aorta closes valves to prevent backflow
Heart Murmur
: when blood goes backward b/c defective valve
Some are born with
Damaged b/c of infection
If bad enough, doctors put in mechanical valve
Maintaining Heart Beat
Some cardiac muscles contract/relax w/o signal from nervous system (auto rhythmic)
Sinoatrial node(pacemaker)
: Sets rate/timing cardiac muscle cells contract
Some arthropods have pacemakers located outside heart
Electrocardiogram
: Electrodes on skin record electric activity of heart
Impulses from SA cause atria to contract in unison
Atrioventricular Node
: Impulses from SA reach auto rhythmic cells in wall btwn left/right atria
Impulses delayed for 0.1 sec. so atria can empty
Signals from AV go to heart and ventricular walls using bundle branches and Purkinje fibers
Sympathetic division speeds up pacemaker to increase O2 when needed
Parasympathetic division slows pacemaker conserving energy when relaxing
Hormones like epinephrine speeds pacemaker
Blood Pressure
Structure and Function
Endothelium
: Epithelial cells lining lumen, makes fluid flow smoother
Tissues surround endothelium, dif. based on structure b/c of function
Capillaries
Smallest blood vessel
Endothelium and basal lamina
Where substance exchange btwn blood and interstitial fluid occurs b/c walls are thin enough
Artery
2 layers of tissue surrounding epithelium
Outer layer is connective tissue so it can stretch and collagen for strength
Other layer is smooth muscle and more elastic fibers
Can handle lots of blood flow
Signals from nervous system and circulating hormones control smooth muscle constriction and dilation
Vein
Bring blood back to heart
1/3 of an artery
Has valves to control flow of blood
Velocity
Same amt of fluid has to flow in big diameter as small diameter
Even though capillaries are smaller than artery, velocity slows b/c theres more capillaries
Speeds up as it goes from capillaries to veins b/c smaller TOTAL cross-section area
Blood Pressure
Changes During Cardiac Cycle
Systolic Pressure
: When heart contracts
Every time ventricles contract, blood pressure inc. and stretches walls of arteries
More blood comes in than leaves so walls stretch to accommodate
Diastolic Pressure
: When arterial walls relax
Before enough blood leaves to relieve pressure in walls, more comes in so its constantly under pressure
As a result, blood is constantly flowing to arterioles and capillaries
Regulaton
Vasoconstriction
: Smooth muscle in arteriole walls narrow
Inc. blood pressure upstream
Vasodilation
: Smooth muscles relax and walls expand
Blood pressure dec.
Nitric oxide causes vasodilation and endothelin causes vasoconstriction
Nervous and endocrine system regulate NO and endothelin
Pressure and Gravity
BP for healthy 20y/o at rest is 120/70
Measured in mmHg
When standing gravity is stronger at bottom so bp in head is less than heart
When bp in brain is below normal you faint so your body is level and inc. blood flow to brain
Animals w/ longer necks have higher bp to get enough O2 to brain
Capillary Function
Every part of body is supplied w/ blood
More important organs like brain, heart, kidneys are given more blood
Blood flows more to places depending on situation: skin to regulate temp, digestive tract after meal, muscles during exercise
Don't have smooth muscle to direct blood flow so they constrict and dilate to control
Sphincters like those in digestive tract can also control flow
Nerve impulses(hormones) regulate blood flow and are released when needed
Macromolecules carried in vesicles
Form on one side by endocytosis
Expel contents on other side by exocytosis
Happens at endothelium
Small molecules diffuse through microscopic pores
Blood pressure drives fluid out
Blood proteins pull fluid back
Fluid Return
Lymphatic System
: returns lost fluid and protein to blood
Lymph drains into veins at base of neck
Transfers lipids from small intestine to blood
Fluid and protein leak from capillaries to interstitial fluid
Vessels have valves to prevent back flow
Contraction of walls draw fluid into vessels
Lymph Nodes
: Filter lymph
Inside is connective tissue w/ spaces of white blood cells
When fighting infection WBC multiply causes lymph nodes to swell
May trap cancer cells
Blood Compounds
Composition and Function
Plasma
Ions/proteins in plasma help osmotic regulation, transport, and defense
Inorganic salts (ions) buffer blood
Concentration of ions affects composition of interstitial fluid
Albumins (plasma protein) act as buffer against pH change
Antibodies (plasma protein) fight foreign bodies
Apolipoprotein help lipids travel through blood
Fibrinogens form clots
Cellular Elements
Erythrocutes(red blood cells)
Transport O2
Shape inc. surface area, inc. diffusion of O2
Hemoglobin
: iron containing protein
Generate ATP anaerobically so they don't consume O2 they're carrying
Sickle cell prevents exchange of gases and waste
Leukocytes(white blood cells)
Fight infection
Some phagocytic
Outside circulatory system in interstitial fluid
Platelets
Bone marrow
Structure
Stem Cells
Before cell becomes specialized
Reproduce indefinitely
Found in bone marrow, umbilical cord
Lymphoid Progenitor Cells become lymphocytes
Myeloid Progentor Cells become everything else
Blood Clotting
Blood coagulates
Exposed protein attracts platelets
Formation of thrombin from prothrombin which turns fibrinogen to fibrin and forms clot
Hemophilia
: Blood doesn't clot
Positive feedback
Cardiovascular Disease
Different Types
Artherosclerosis
: Hardening of arteries b/c of fatty deposits
Low density lipoprotein
delivers cholesterol to cells for membrane production
High density lipoprotein
returns extra cholesterol to the liver
Heart Attack(myocardial infarction)
: Damage/death of cardiac muscle b/c of blockage of arteries
Heart needs lots of O2 so if a large portion is affected it'll stop beating
Stroke
: death of nervous tissue in brain b/c lack of O2
Result of rupture or blockage of arteries
Specialized Respiratory Surfaces
Respiratory Surfaces
Cells doing gas exchange has plasma membrane that has contact to aqueous solution
Rate of diffusion of O2 and CO2 is proportional to surface area and inversely proportional to square of distance
Gas exchange is quicker when area is large and path is short
Porifera exchanges gas btwn environment and cells directly
Gills
Total surface area greater than body exterior
Ventilation
: Maintain partial pressure gradient of O2 and CO2
Inc. ventilation by moving gills through water or water over gills
Countercurrent exchange
: Exchange of substance/heat btwn 2 fluids moving in opposite directions
In fish, the 2 fluids are blood and water
Respiratory Media
Air is less dense than water so it's easier to breathe
Humans extract 25% of O2
Water has 30% less O2 than air
Aquatic animals use more energy for gas exchange
Tracheal Systems
Tracheal system
: Air tubes branching throughout body
Largest tubes (tracheae) open to the outside
Exchange happens over a short distance
Muscle contractions inc. ventilation
Partial Pressure
: driving force of gas exchange
Helps predict movement of gas during exchange
Gas always goes from higher pressure to lower pressure
Lungs
Connected to other parts of the body by the circulatory system
Common in vertebrae
In amphibians, gas exchange happens through the skin when in water
Larynx
: Upper part of respiratory tract
Trachea
: Tube in neck for air
Air goes from larynx to trachea to bronchi in lung to bronchioles
Alveoli
: Where gas exchange occurs in mammals
Breathing
Bird
Air sacs direct air flow through lungs
Parabronchi, site of gas exchange
Requires 2 cycles of inhalation and exhalation
Mammal
Negative Pressure Breathing
: Pull air in
Expand thoracic cavity, lowering air pressure in lungs causing gas to flow in
Inhalation requires work, but exhalation doesn't
Tidal Volume
: Volume of air inhaled/exhaled
Vital Capacity
: Tidal volume during max inhalation/exhalation
Residual Volume
: Air remaining after forced exhalation
The older you get, the more residual volume
Amphibian
Positive Pressure Breathing
: Inflate lungs with forced airflow
Oral cavity expands forcing air in
Mouth closes, pushing air down trachea
Body walls compress pushing air out
Control Breathing
Involuntary
pH of fluid indicates CO2 concentration
The more metabolic activity, the more CO2, the more H+ (protons)
Medula inc. depth + rate of breathing tip CO2 is normal
Osmoregulation and Excretion
Excretory System
Processes
How Urine is Produced
Blood comes in contact w semi-permeable membrane
Hydrostatic pressure drives filtration
Water, sugars, amino acids, nitrogenous waste cross membrane and form filtrate
Steps
Reabsorption
: Transport epithelium takes up water, glucose, vitamins, hormones, amino acidsfrom filtrate and returns to body fluid
Secretion
: Toxins/excess ions extracted from body fluid and added to excretory tubule (active transport)
Filtration
: Excretory tubule collects filtrate from blood. Water and solutes cross membrane into excretory tubule
Excretion
: Urine leaves system and body
Survey of Systems
Metanephridia
Excretory organs collect fluid directly from coelom
Pairs of metanephridia are found in each section of annelid
Ciliated funnel surround internal opening
Cilia draw fluid to collecting tube (storage bladder)
Nitrogenous wastes remain in tubule and excreted into environment
Malpighian Tubules
Remove nitrogenous waste
Osmoregulation
From dead-end tips to digestive tract
No filtration
Epithelium secretes certain solutes into lumen of tubule
Water is reabsorbed
Protonephridia
Excretory system of platyhelmnithes, no coelom
Tubules branching throughout body
Flame bulbs cap branches
Each flame bulb has cilia projecting into tubule
Cilia draws water/solutes from interstitial fluid through flame bulb
Filtrate empties as urine
Kidneys
Tubules that are arranged similar to capillaries
2 Ducts (ureter) drain into urinary bladder
Expelled through urethra
Regulated by a sphincter
Nephron
Blood Filtrate
Proximal Tubule
Reabsorption recaptures ions and water
Transfer of NaCl out of tubule drives passive transport of Cl-
Water moves from filtrate to interstitial fluid along with water, reducing filtrate volume
Glucose, amino acids, K+ are transported from filtrate to interstitial fluid then into per tubular capillaries
Processing filtrate maintains constant pH
Waste becomes concentrated and remains in filtrate while water and salts are reabsorbed
Actively transported to lumen of proximal tube
Descending Limb of Loop of Henle
After leaving proximal tubule, it enters the loop of Henle
Aquaporin
: Proteins making transport epithelium permeable to water
No channels for salt
Interstitial fluid bathing tubule must be hypertonic to filtrate
Highest osmolarity occurs at elbow
Distal Tube
K+ secreted into filtrate
NaCl reabsorbed from filtrate
pH regulation by secretion of H+ and reabsorption of HCO3-
Collecting Duct
Processes filtrate into urine and carry to renal pelvis
Presence of water channels controlled by hormones regulating blood pressure
Ascending limb of Loop of Henle
Transport epithelium lacks water channels
Epithelial membrane facing filtrate is impermeable to water
2 Specialized regions:
Thin segment near loop tip where NaCl diffuses out of permeable tubule into interstitial fluid
Thick segment adjacent to distal tube where epithelium actively transports NaCl to interstitial fluid
Nitrogenous Waste
Forms
Urea
Product of metabolic cycle
Combination of ammonia and carbon dioxide in liver
Mammals, most amphibians, sharks, some bony fish
Low toxicity
Uses up energy during metabolic cycle
Uric Acid
Insects, land snails, reptiles, birds
Nontoxic and doesn't dissolve in water
Uses more energy than urea
Rare, but can happen to humans (gout)
Ammonia
Ammonium (NH4+)
Ammonia (NH3)
Secreted by most bony fish
Can only be tolerated in low concentrations
Some species use energy to make it less toxic before expelling
Lost by diffusion
Osmoregulation
Challenges and Mechanisms
Osmoconformer
: Isoosmotic with surroundings
Marine animals are osmoconformers
Osmoregulator
: Control internal osmolarity independent of environment
In hypertonic environment, they release excess water, in hypotonic environment, they take in more water
Stenohaline
animals aren't able to survive in environments with major osmolarity change.
Euryhaline
animals can
Marine Animals
Most are osmoconformers
Osmolarity is same as seawater
Sharks expel nitrogenous waste (urea)
High concentration of urea denatures proteins
Trimethylamine oxide (TMAO)
protects proteins from urea
Freshwater Animals
Body fluids must be hyperosmotic
Relies on excreting large amounts of dilute urine and drinking no water
Salts lost in urine and diffusion are replaced by eating and salt uptake in gills
Salmon osmoregulate like other freshwater fish in freshwater, in saltwater they produce cortisol, inc. # and size of salt producing cells
Temporary Waters
Anhydrobiosis
: Dormant state when habitat dries up
Animals that live in water and land can lose a majority of the water in their body and rehydrate when water is available
Land Animals
Land creatures have a covering that prevents them from losing water
Exoskeletons on insects, skin on humans, wax on plants
Lose water in urine, feces, sweat so constantly need to replenish by drinking
Energetics
Maintaining osmolarity uses energy
How much energy is used depends on how different the environment is
5% of metabolic rate of fish
Minimizing difference between body and environment saves energy
Osmosis and Osmolarity
Osmolarity
: Unit for solute concentration (mOsm/L) # of moles of solute per liter of solution
Osmolarity of humans is 300 mOsm/L
Osmolarity of seawater is 1,000 mOsm/L
Isoosmotic
: 2 solutions w/ same osmolarity
Water moves from a hypertonic solution to a hypotonic solution
Hormonal Circuits
Renin-Angiotensin-Aldosterone System
: Regulates kidney function
Juxtaglomerular apparatus
: Specialized tissue consisting of cells around arteriole
Supplies blood to the glomerulus
When blood pressure/volume drops, JGA releases renin
Cleaves angiotensinogen to angiotensin ll that triggers vasoconstriction
Inc blood pressure and dec blood flow to capillaries in kidney
Regulation of Salt and Water
Atrial Natriuretic Peptide
opposes RAAS
ADH lowers blood Na+ but ANP increases Na+ reabsorption
Walls of atria release ANP to inc blood volume/pressure
Inhibits release of renin
Antidiuretic Hormone(vasopressin)
Bind to and activate membrane receptors on surface of collecting duct cells
Directs insertion of aquaporin proteins into membrane lining of collecting duct
More aquaporin channels, more water reabsorbed, less urine
Osmolarity inc, release of ADH, inc water reabsorption, osmolarity goes back to set point, reduces activity of osmoreceptor cells in hypothalamus, ADH secretion reduced
No ADH production leads to dehydration