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Bodily Functions and Processes (Circulation and Gas Exchange (Circulatory…
Bodily Functions and Processes
Circulation and Gas Exchange
Circulatory Systems
Diffusion
Random thermal motion
The exchange of CO2 into the environment and O2 into the cells
Open
The heart pumps hemolymph through the organisms circulatory vessels into the spaces surrounding organs
Hemolymph
Circulatory and interstitial fluid in open circulatory systems
Within the sinuses hemolymph and cells exchange gasses and other chemicals
Closed
Blood
Circulatory fluid that is confined in vessels and separate from interstitial fluid
Heart(s) pumps blood into vessels that branch off and go into the tissues and organs
Chemical exchange occurs between blood and interstitial fluid, and interstitial fluid and cells
Single
Blood travels through the body and returns to its starting point in a single circuit
Commonly found in Sharks, rays and bony fish
Double
The pumps for the two organs are combined at the heart
The right side of the heart pumps deoxygenated blood to the capillaries of the lungs where it may receive O2
The left side of the heart pumps oxygen rich blood to organ and tissues where it loses oxygen and returns to the heart
Found in Amphibians, reptiles and mammals
Mammals have a four chambered heart cleanly dividing oxygen rich and oxygen poor blood
Heart Variation
Fish
Single circulatory system
Blood is pumped through the body in a single circuit, heart only holds oxygen poor blood
Amphibians
Double circulatory system
Three chambered heart, oxygen and oxygenated blood mix
Amphibians take advantage of this by shutting off blood flow to the lungs while they're in water
Mammals
Double circulatory system
Dividing septum in their heart, keeping oxygenated and oxygenated blood separate
Lungs are constantly working so no cutting off or combination is required
Reptiles
Double circulatory system
Turtles, lizards and snakes - blood mixes in the heart
Alligators, Caimans, etc.
Have a complete septum separating the blood, but the pulmonary and systemic circuits connect, allowing no blood in the lungs when they go under water
Blood and All It's Attributes
Blood Pressure
The pressure of circulating blood on the walls of blood vessels
Diastolic Pressure
The lower BP when the ventricles are relaxed
Normal: 70 mm of Hg
Hypertension
High blood pressure
Occurs when BP is 140/90 or higher
Systolic Pressure
The pressure when the heart contracts during ventricular systole
Normal: 120 mm of Hg
Vasodilation
Causes blood pressure in the arteries to fall
Useful when the body gets too hot to release the heat and cool the body off
Vasoconstriction
Increases blood pressure upstream into the arteries
Useful in the cold to keep the core, heart and organs warm so they don't shut down
Lymph Circulation
Lost fluid from capillaries and surrounding tissues is returned here
Lymph
The fluid recovered from the capillaries and tissues
An important part of the immune system, helping to defend the body
Lymph nodes
A mass of connective tissue that has spaces filled with white blood cells
When fighting off infections, white blood cells multiply rapidly, causing them to swell
Blood Components
Plasma
The liquid matrix that blood cells are suspended in
Ions and proteins are dissolved in plasma to work with blood cells to help osmotic regulation
Platelets
Cell fragments that are involved in the clotting process
Pinched-off cytoplasmic fragments of specialized bone marrow cells
Erythrocytes
Red blood cells
The most numerous blood cells
Main function is oxygen transport
Hemoglobin
Iron containing protein that transports oxygen
Leukocytes
White blood cells
Main function is to defend the body and fight infections
Can be found outside the circulatory system patrolling for invaders
Organs and Transport
Veins
Come from venules, converged from cappilaries
The vessels that carry blood back to the heart
Capillaries
Microscopic vessels with very thin porous walls
Networks called capillary beds that infiltrate tissues
Dissolved gasses and other chemicals are exchanged by diffusion
Arteries
Carry blood from the heart to organs throughout the body
Branch off into smaller, arterioles
Respiratory System
Gas Exchange
The uptake of molecular oxygen from the environment and the discharge of carbon dioxide to the environment
Early Breathing Methods
Gills
Outfoldings of the body surface that are suspended in water
Ventilation maintains the partial pressure needed for gas exchange
Tracheal System
A network of air tubes that branch throughout the body
Commonly found in insects
Skin
A dense network of capillaries below the skin helps the exchange of gasses between the circulatory system and the environment
Found in earthworms and some amphibians and other animals
Mammalian Respiration and Organs
Bronchi
Stem from the trachea that lead into each lung
Bronchioles
Finer and finer tubes branching off the bronchi
Trachea
Windpipe, the long tube that leads down to your lungs
Alveoli
Air sacs clustered at the tips of the tiniest bronchioles
Larynx
Covers the glottis, preventing food from entering your trachea
Lungs
Localized respiratory organs where gas exchange takes place
Breathing
Negative Pressure
Pulling air into the lungs
Mammals lower air pressure in their lungs below that of the air outside their body
Diaphragm
A sheet of skeletal muscle that forms the bottom wall of the cavity and helps control the inflation and deflation of the lungs
Positive Pressure
Inflation of the lungs with forced air flow
Muscles lower the floor of the oral cavity, which rises and forces air down into the trachea
Partial Pressure
The pressure exerted by a particular gas in a mixture of gasses
Table 42.1: Comparing Air and Water as Respiratory Media
Osmoregulation and Excretion
General term for the processes by which animals control solute concentrations and balance water gain and loss
Osmosis
The way in which water enters and leaves cells
Osmolarity
The number of moles of solute per liter of solution
Ex: The osmolarity of human blood is 300 milliosmoles per liter
Osmoregulatory Mechanisms
Osmoconformer
To be isoosmotic with ones surroundings
All are marine animals
No tendency to gain or lose water
Osmoregulator
To control internal osmolarity independent of that of the external environment
Allows animals to live in freshwater and on land
Osmoregulation in Animals
Marine
Most are osmoconformers
Osmolarity is the same as seawater
Cannot survive in freshwater
Freshwater
Osmoregulators
Bodily fluids must be hyperosmotic because they cannot handle low salt concentrations
Land
Adaptations to reduce water loss are vital for organisms to survive on land
Osmoregulators
Mammalian Excretory Organs
Kidney
Functions in both osmoregulation and excretion
Urine is produced here and sent down
Uterer
Ducts in which urine is sent down to reach the bladder
Urinary Bladder
A common sac where urine is drained into from the kidneys and both uterers
Urethra
The tube through which urine is expelled from the bladder and out of the body
Nephrons
The functional units of the vertebrate kidney
Cortical Nephrons
Make up 85% of the nephrons in the kidneys
Reach only a short distance into the medulla
Juxtamedullary Nephrons
Extend deep into the medulla
Essential for the production of urine and water conservation in mammals
Structure
Outer Medulla
2) Descending limb of loop of Henle
Make the transport epithelium freely permeable to water to further reduce filtrate volume
3 cont.) Thick Segment of ascending limb
Movement of sodium out of the filtrate continues, leaving the filtrate more dilute as it continues
Inner Medulla
3) Thin segment of ascending limb
Sodium diffuses out of the permeable tubule and into the interstitial fluid
5) Collecting Duct
Process filtrate into urine which then leads it out into the utrerers
Cortex
1) Proximial Tubule
Reabsorption of ions, water, and valuable nutrients is critical here
4) Distal Tubule
Plays a key role in regulating potassium and sodium concentration of bodily fluids
Excretory Wastes
The most significant waste products are the nitrogenous breakdown products of proteins and nucleic acids
Urea
The product of an energy consuming metabolic cycle that combines ammonia with carbon dioxide in the liver
Very low toxicity
Very high energy cost to produce urea from ammonia
Uric Acid
Relatively nontoxic
Does not readily dissolve in water
Can be excreted with very little water loss
Ammonia
Most common in aquatic species
Need access to lots of water
Can only be tolerated at low concentrations
Excretory Processes
Reabsorption
Recovers useful molecules and water from the filtrate and returns them to the body fluid
Secretion
Toxins and excess ions are extracted from body fluids and added to the contents of the excretory tube
Filtration
The excretory tubule collects a filtrate from the blood
Water and solutes are forced across a seletive permeable membrane
Excretion
Altered filtrate leaves the system and body as urine
