Animal circulation, gas exchange, osmoregulation and excretion
Types of circulatory systems
Closed circulatory system
Open circulatory system
Example of organisms
Some molluscs
Arthropods
Fluid is HEMOLYMPH
Chemical exchange occurs between hemolymph and body cells
Advantages
Lower hydrostatic pressure
Less energy expenditure
Fluid is blood
Chemical exchange occurs between blood and the interstitial fluid, and between interstitial fluid and the body cells
Example of organisms
Advantages
Annelids, cephalopods, and all vertebrates
Relative high blood pressure
Well suited to regulating the distribution of blood to different organs
Single circulation
Bony fishes, rays and sharks have a heart consisting of 2 chambers: an atrium and a ventrical
Blood passes through the heart once in each complete circuit through the body
Double circulation
It has 2 circuit
For amphibians, reptiles, and mammals
Pulmonary circuit
It is the right side of the heart
It delivers oxygen poor blood to the capillary beds of the gas exchange tissues
Systemic circuit
It is the left side of the heart
It is where the oxygen rich blood goes after leaving the gas exchange tissues
Blood vessel
Capillaries
Smallest blood vessels
Their walls consist of just endothelium and basal lamina
Where gas are exchanged by diffusion between the blood and the interstitial fluid around cell tissues
Arteries
have 2 layers surrounding the endothelium
Their carry blood from the heart to organs
Outer layer- connective tissue
Inner layer- smooth muscle
Walls are thick, strong and elastic
Veins
walls are only about 1/3 as thick as that of an artery
Contain valves, which maintain a unidirectional flow of blood
have 2 layers surrounding the endothelium
Carry blood back to the heart
Inner layer- smooth muscle
Outer layer- connective tissue
Mammalian heart
Has 4 chambers
Has 2 ventricles
Has 2 atria
Serve as collection chambers for blood returning to the heart from lungs and other tissues
Pump blood throughout the body via the systemic circuit
Has 4 valves
2 atrioventricular valves
are between each atrium and ventricle
keep blood from flowing back into atria
Semilunar valves
keep blood from flowing back into the ventricle
Located at the 2 exists of the heart
one is where aorta leaves left ventricle
one is where pulmonary artery leaves the right ventricle
Blood
Osmosis is the movement of water through a semipermeable membrane from the hypotonic region to the hypertonic
Marine water animals
Most marine animals are osmoconformers; are isosmotic with its surroundings
Some marine animals are osmoregulators; they control internal osmolarity independent of that of the external environment
Marine water is strongly dehydrating environment
Fresh water animals
Fresh water animals face the problem of gaining water by osmosis and losing salts by diffusion
Few aquatic invertebrates that live in temporary ponds can lose almost all their body water and survive. This adaptation is called ANHYDROBIOSIS
Nitrogenous wastes
Ammonia
Most common in aquatic species
In many invertebrates, ammonia release occurs across the whole body surfaces
Urea
Most terrestrial animals and many marine species mainly excrete urea
In vertebrates, urea is the product of metabolic cycle that combines ammonia with CO2 in the liver
Advantage: low toxicity
Disadvantage: energy cost
Uric acid
Many reptiles, insects, land snails
Non toxic
Humans generate a small amount of uric acid from purine breakdown
Nephron
Cortical nephron
Juxtamedullary nephron
Reach only a short distance into the medulla
Extend deep into the medulla
Essential for the production of urine that is hyperosmotic to body fluids
Filtrate passes through 3 major regions of the nephron
Proximal tubule
Loop of Henle
Distal tubule
It is supplied with blood by an afferent arteriole
Major excretory organs
Urinary bladder
Urethra
Ureter
Kidney
Ureter, urinary bladder and urethra transport urine
Blood pressure
contraction of a heart ventricle generates blood pressure, which exerts force in all directions
Normal blood pressure is 120/70
Lymph circulation
By diffusion
Lymph nodes are lymph filter organs
Are fluid lost by capillaries
components
plasma is 55%
Water- solvent
Ions- blood electrolytes
are Na, Ca, Mg, Cl, K and bicarbonate
they function as buffer, maintain osmotic balance and regulate membrane permeability
Proteins
Immunoglobulins- defense
Albumin- maintain osmotic pressure and are pH buffer
Apolipoproteins- lipid transport
Fibrinogen- blood clotting
Cellular elements 45%
Substances transported by blood
Nutrients
Waste products of metabolism
Respiratory gases
Hormones
Platelets
Erythrocytes
Leukocytes
Breathing
Positive pressure breathing
Is a breathing in which air is forced into the lungs
negative pressure breathing
Air is pulled into the lungs
Diaphragm is a sheet of skeletal muscle that forms the bottom wall of the cavity
Mammalian respiratory system
Nostril- Nasal cavity- pharynx- larynx- trachea-lungs- bronchioles- alveoli
lined with mucus to trap pollens and cilia to move mucus
Gas exchange occurs in alveoli
Alveoli produce surfactant
Diverse excretory systems
Metanephridia
Malpighian
Protonephridia