mammalian lungs are or are not a counter current

respiratory surface requires a moist epithelium, oxygen and carbon dioxide must be dissolved in water to diffuse, how then do you conserve water?

air moving in and out of same passageway

-only possible in terrestrial animals

-i.e. trachea

-makes conservation of water possible

inhal by contracting the daphragm; lungs are just stretch sacs that cannot move air by themselves

passive, diaphragm relaxes and it causes a decrease in lung size

-air forced out

one of the worst sources of toxic air pllutants

-inhibits or destroys cilia and epithelial cells

-causes more toxins to reach the lungs; frequent coughing is the body's attempt at cleaing itself

-carbon dioxide concentration in blood gets high

-reacts with water in cerebrospinal fluid and forms carbonic acid (H₂CO₃)

-neurons in medulla sense drop and then breathing rate increases

more efficient than in mammals

-one-way flow of air through lungs (we have in and out flow)

-birds have paired lungs but 8 or 9 air sacs

-air sacs push air through lungs in one direction (not like tidal breathing)

-allows for countercurrent exchange in lungs, so much more efficient than mammals in uptake of oxygen

all reptiles and most amphibians have lungs (but not as elaborate as mammals)

-less surface area

hydra, flatworm

-essentially internal transport with no circulatory system

pump heart

circuitry

1 or many

-muscular tube from simple to complex (4-chambered)

-pumps in one direction

1. vessels to take pumped blood from heart to rest of tissues

2. valves keep bolood flowing in correct direction

blood (hemolymph) flows into large open areas (sinuses)

-not always enclosed in vessels

-flows through tissue in extracellular (intersitial) spaces

-mollusks, arthropods, (insects, crustacenas)

-typically dorsal heart with holes (ostia)

-hemolymph in space around heart (pericardial sinus) enters heart via ostia when heart relaxes, and moves forward when heart contracts

have relatively underdeveloped system

-doesn't have to distribute oxygen (b/c of tracheal system)

-hemolymph leaves heart via anterior artery and is no longer in vessels

-percolates through rest of body, bathing organs and tissues util it gets back to pericardial sinus

-movement of hemolymph faster during insect activity

blood travels through body in well-defined vessels: arteries, capillaries and veins

-blood cells and proteins saty inside the vessels, small molecules and water move in and out of capillaries

-blood and extacellular fluid (interstitial fluid) are of different composition

singel current of blood flow: heart > gills > tissues > heart

-chambers of heart in line, no mixing of deoxygenated /oxygenated blood

-blood pressure after gills is low, limits rate of oxygen to rest of body

2-circuit ciculation system:

gills/pulmonary circuit, heart, systemic circuit, heart

-both amphibians and reptiles have left and right atrium to accommmodate this 2 circuit system

one

-mixing of deoxygenated and oxygenated blood

reptiles have how many ventricles in heart?

completely separate pulmonary and systemic circuits

4 chambered heart

-can use higher pressure to get to systemic circuit without blowing lungs out

-no dilution of oxygenated blood

when blood leaves heart

pulmonary semilunar valve

aortic semilunar valve

relaxing / filling with blood

-both atria and ventricles relaxed, blood enters the heart from the venae cavae (R) and the pulmonary veins (L)

-bi and tricuspid valves open, blood flows from atria into ventricles

both atria contract and this pushes the rest of the blood into ventricles (systole)

-then ventricles contract simultaneouly. after atrial contraction, bicuspid and tricuspid valves close and valves at base of pulmonary arteries and aorta (semilunar valves) open as the ventricles contract

in diastole, everything is relaxed and everything is being filled with blood

during systole, atria contract first, then ventricles

systole - the heart contracting

diastole - elastic artery walls help push blood along

120/75

120mm Hg = systolic pressure

75mm Hg = diastolic pressure

S-A node initiates beat (located on right atrium)

-atria contract

 -impulse hits A-V node (wall between right atrium and right ventricle) which slows down impulse so ventricles have time to fill

-impulse travels through Bundle of His (septum) and down to bottom of ventricles, which then contract

conduct impulses like a nerve

-is self-stimulating

electrocardiogram

-record of the electrical changes occurring in the heart

-useful because if beating is out of synch, it shows up on EKG

_____ % of blood is plasma

_____% percent water and _____% dissolved molecules

55%

90%, 10%

erythrocyte

life span?

where it's formed?

dead ones removed by?

red blood cell, average life span in blood = 120 days

-most numerous type of blood cell

-formed in the bone marrow

-removed by liver