Download Structure, Function, Homeostasis Circulation and Gas Exchange

Structure, Function, Homeostasis
Circulation and Gas Exchange
Invertebrate Circulation
 Membranes
o Lower animals (sponges)
o Exchange with environment achieved by water flowing across body membranes
o Passive transport (osmosis) of water
o Membrane 1 cell thick
 Gastrovascular cavities
o Cnidarians (jellyfish, hydra), planarians, flatworms
o One opening
o Organism is 2 cells thick
o Separates internal environment from external environment
o Keeps all cells bathed in an aqueous solution
o Only inner cells are able to exchange nutrients/wastes
 Open/closed circulatory systems
o Basic components of circulatory system
 Circulatory fluid
 Interconnecting vessels
 Muscular pump (heart)
o Open
 Arthropods (insects, spiders, crustaceans), mollusks (snails, clams)
 No distinction between blood and interstitial fluid (hemolymph)
 Heart
 Contracts – pushes blood out
o Heart pumps hemolymph to interconnected sinuses that bathe tissues
o Blood bathes organs directly
 Relaxes – draw blood in
o Muscles in body contract to help push blood back into heart
 Advantages
 Lower blood pressure = lower energy expenditure
 No blood vessels = less energy to maintain
 Open circulatory system can serve other functions (mollusks = hydrostatic skeleton)
 Disadvantages
 Lower blood pressure
 Inability to control blood distribution/velocity
 Low metabolic rate (as a result of previous point)
o Closed
 Vertebrates, some mollusks (squid, octopuses), earthworms
 Blood is confined to vessels and is distinct from interstitial fluid
 Advantages
 Every cell of the body is within one to three cells distance from a capillary
o If more, it would take too long for blood to transport through all cells
 Greater control of oxygen delivery to tissues
 Allows for greater metabolic rate/activity
 Animals with high metabolic rates have more complex circulatory systems
Structure, Function, Homeostasis
Circulation and Gas Exchange
Vertebrate Circulation
 Heart
o Atrium (one) or atria (two) (different forms of the same word)
 Chamber that receives blood returning to the heart
o Ventricles
 Chamber that pumps blood out of the heart
 Right
 Goes to lungs
 Smaller because short distance to lungs
 Left
 Goes to brain and extremities
 Larger because large distance to extremities
 Contract with greater force in order to reach extremities
o Circulation
 Pulmonary
 Carries depleted blood to the lungs
 Returns oxygen-rich blood to the heart
 Lungs, gills
 Systemic
 Distributes oxygenated blood to the tissues of the body
 Body tissues
Blood Vessel
Arteries
Structure
 Thick middle and outer layers

Elastic (recoil)
Arterioles

Smaller diameter
Capillaries

Venules
Veins



Only an inner layer a few cells
thick
Large diameter
Not as thick as arteries
One-way valves
Function
 Accommodates high blood
pressure
 Maintains blood pressure even
when heart relaxes
 Maintains pressure as blood goes
to capillaries
 Gas exchange



Connect capillaries to veins
Blood pressure lower here
Prevents backflow
Structure, Function, Homeostasis
Fish
 Two-chambered
heart
 Single circuit of
blood flow
Amphibians
 Three-chambered heart
 Two circuits of blood flow
o Pulmocutaneous
o Systemic
 Some mixing of oxygen-rich
and oxygen-poor blood
Circulation and Gas Exchange
Reptiles
 Three-chambered heart
 Two circuits of blood flow
 Septum partially divides
the single ventricle
o Reduces mixing of
blood
Cardiac Cycle
 One complete sequence of pumping
o Systole (contraction phase)
o Diastole (relaxation phase)
 Cardiac output depends on heart rate (number of beats per minute) and stroke volume
o Average resting cardiac output: 5.25 L/min
o Number goes up during exercise
 Regulated by electrical impulses that radiate throughout heart
o Pacemaker
 Sets the rate and timing at which all cardiac muscle cells contract
 Located in the wall of the right atrium
 Myogenic heart
 Pacemaker located in the heart
 Pacemaker made up of specialized muscle tissues
 Neurogenic heart
 Pacemakers originate in motor nerves outside the heart
Mammals and birds
 Four-chambered
heart
 Completely
separates oxygenrich and oxygenpoor blood
Structure, Function, Homeostasis
Circulation and Gas Exchange
Blood
Blood Types
Blood Type
A
B
AB
O
Antigens (Proteins)
on Blood Cells
A
B
A and B
Neither A nor B
Blood Type
A
B
AB
O
Rh+
Rh-
Antibodies in
Plasma
Anti-B
Anti-A
Neither anti
Both anti
Possible Alleles
AA or AO
BB or BO
AB
OO
Rh+Rh+ or Rh+RhRh-Rh-
Can Give Blood To
A, AB
B, AB
AB
O, A, B, AB
Can Receive Blood
From
O, A
O, B
O, A, B, AB
O
Dominant/Recessive
A dominant over O
B dominant over O
A and B are co-dominant
O is recessive
Rh+ is dominant
Rh- is recessive
Structure, Function, Homeostasis
Cardiovascular disease
 Thrombus (non injury-induced clot)
o Clogs coronary artery or artery to the brain
o Heart attack
 Death of cardiac muscle tissue
 Due to prolonged blockages of coronary
arteries
o Stroke
 Death of nervous tissue in the brain
 Atherosclerosis
o Growths (plaques) develop in the inner walls of the
arteries
 Narrow vessels are more likely to tram an
embolus and are common sites for thrombus
formation
o Risk factors
 Hypertension promotes atherosclerosis
 Can be controlled by lifestyle and
diet
 Genetics
 Smoking, lack of exercise, high cholesterol
 LDL/HDL in blood
Circulation and Gas Exchange