Biology 112 Exam 2

Breaking down of food into its chemical components to provide energy

Food is taken in, taken apart, and taken up in the process of animal

All animals consume their food

Eat mainly autotrophs (plants and algae which make their own food)

Eat other animals

Regularly consume animals as well as plants or algal matter

• -Carbohydrates must be broken down into simple sugars (glucose)
• -Proteins must be broken down into amino acids
• -Lipids must be broken down into fatty acids

Chemical energy, which is converted into ATP and powers the processes in the body

Organic carbon and organic nitrogen in order to construct organic molecules

Required by cells and must be obtained from dietary sources

• •Essential amino acids
• •Essential fatty acids
• •Vitamins
• •Minerals

• -Animals require 20 amino acids and can synthesize about half from molecules in their diet
• -The remaining amino acids, the essential amino acids, must be obtained from food in preassembled form
• -A diet that provides insufficient essential amino acids causes malnutrition called protein deficiency
• -Meat, eggs, and cheese provide all the essential amino acids and are thus “complete” proteins
• -Most plant proteins are incomplete in amino acid makeup.  A combination is needed to ensure proper nutrition

• -Animals can synthesize most of the fatty acids they need
• -The essential fatty acids are certain unsaturated fatty acids that must be obtained from the diet

• Organic molecules required in the diet in small amounts; required for biochemical functions.
• -13 vitamins essential to humans have been identified
• -Vitamins are grouped into two categories: fat-soluble and water-soluble

Simple inorganic nutrients, usually required in small amounts.  Ingested as salts dissolved in food and water and include sodium, potassium, calcium, phosphorous, magnesium, iron, etc…

• Result of a diet that consistently supplies less chemical energy than the body requires.  An undernourished individual will
• -Use up stored fat and carbohydrates
• -Break down its own proteins
• -Lose muscle mass
• -Suffer protein deficiency of the brain
• -Die or suffer irreversible damage

• Long-term absence from the diet of one or more essential nutrients
• -Can cause deformities, disease, and death
• -Can be corrected by changes to a diet

Ingestion, digestion, absorption, and elimination

Act of eating

Aquatic animals, which sift small food particles from the water

Animals that live in or on their food source

Suck nutrient-rich fluid from a living host

Eat relatively large pieces of food

• Breaking food down into molecules small enough to absorb
• -In chemical digestion, the process of enzymatic hydrolysis splits bonds in molecules with the addition of water

Uptake of nutrients by body cells

Passage of undigested material out of the digestive compartment

• Specialized compartments
• -These compartments reduce the risk of an animal digesting its own cells and tissues

• -Intracellular digestion
• -Extracellular digestion

Digestion of food particles within cells; generally in protists; use of food vacuole with hydrolytic enzymes

Occurs in compartments that are continuous with the outside of the animal’s body.  The breakdown of food outside of cells occurs within a gastrovascular cavity-function in both digestion and distribution of nutrients (2 way system), or a complete digestive tract-has mouth, digestive tract, and anus (a.k.a. alimentary canal)

• More complex animals have a digestive tube with two openings, a mouth and an anus
• -This digestive tube is called a complete digestive tract or an alimentary canal
• -It can have specialized regions that carry out digestion and absorption in a stepwise fashion

• -The mammalian digestive system consists of an alimentary canal and accessory glands that secrete digestive juices through ducts
• -Mammalian accessory glands are the salivary glands, the pancreas, the liver, and the gallbladder
• -Food is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canal
• -Valves called sphincters regulate the movement of material between compartments

• -3 pairs of salivary glands
• -pancreas
• -liver
• -gallbladder

• -Special proteins that regulate the rate of nearly every biochemical reaction
• -Required to break down complex food molecules into their component parts in digestion
• -pH, temperature, concentration of it and substrates affect its activity

• -The First Stage of Digestion: Mouth
• -The Second Step in Digestion:  The Stomach
• -The Third Step:  The Small Intestine
• -Pancreatic Secretions
• -Bile Production by the Liver
• -Secretions of the Small Intestine
• -Absorption in the Small Intestine
• -The Last Step: Absorption in the Large Intestine
• -Elimination

• -The first stage of digestion is mechanical and takes place in the oral cavity
• -Teeth:  function in chewing and formation of a bolus.  Types of teeth
• --Incisors
• --Canines
• --Premolars and molars
• -Salivary glands deliver saliva to lubricate food
• -Teeth chew food into smaller particles that are exposed to salivary amylase.  Salivary amylase is secreted by the parotoid, sublingual and submandibular salivary glands initiating breakdown of glucose polymers (starch and glycogen) into smaller polysaccharides and/or maltose
• -The tongue shapes food into a bolus and provides help with swallowing
• -The region we call our throat is the pharynx, a junction that opens to both the esophagus and the trachea (windpipe)
• -The trachea leads to the lungs; it is not part of the digestive system
• -The esophagus conducts food from the pharynx down to the stomach by peristalsis
• -Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract
• -Coughing occurs when the swallowing reflex fails and food or liquids reach the windpipe

• -The stomach (volume = approx. 1 liter (fully distended)) stores food and secretes gastric juice, which converts a meal to acid chyme which is produced by gastric glands
• -Gastric (stomach) juice is made up of hydrochloric acid and the enzyme pepsin
• -Parietal cells secrete hydrogen and chloride ions separately
• -Chief cells secrete inactive pepsinogen, which is activated to pepsin when mixed with hydrochloric acid in the stomach
• -Alkaline mucus protects the stomach lining from gastric juice
• -Coordinated contraction and relaxation of stomach muscles churn the stomach’s contents
• -Sphincters prevent chyme from entering the esophagus and regulate its entry into the small intestine (pyloric sphincter)-Gastric ulcers, lesions in the lining of the stomach, are caused mainly by the bacterium Helicobacter pylori

• -Consists of 3 regions: duodenum, jejunum, and ileum
• -The small intestine is the longest section of the alimentary canal
• -It is the major organ of digestion and absorption
• -The first portion of the small intestine is the duodenum where most digestion and absorption occurs.  Here acidic chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself.

• The pancreas produces proteases trypsin and chymotrypsin, protein-digesting enzymes that are activated after entering the duodenum
• -Pancreatic secretions are alkaline and this neutralizes the acidic chyme
• -Role of pancreas:  secretes the following enzymes:
• --Trypsin/chymotrypsin:  digest proteins
• --pancreatic amylase:  digests carbohydrates
• --pancreatic lipase:  digests lipids
• -Secretion of enzymes is triggered by release of hormones from intestinal mucosa

• -In the small intestine, bile aids in digestion and absorption of fats
• -Bile is made in the liver and stored in the gallbladder
• -Role of liver:  secretes bile; stores excess glucose, iron, and vitamins; detoxifies alcohol

• -The epithelial lining of the duodenum, called the brush border, produces several digestive enzymes
• -Enzymatic digestion is completed as peristalsis moves the chyme and digestive juices along the small intestine
• -Most digestion occurs in the duodenum; the jejunum and ileum function mainly in absorption of nutrients and water

• -The small intestine has a huge surface area, due to villi and microvilli that are exposed to the intestinal lumen
• -The enormous microvillar surface greatly increases the rate of nutrient absorption
• -Each villus contains a network of blood vessels and a small lymphatic vessel called a lacteal
• -After glycerol and fatty acids are absorbed by epithelial cells, they are recombined into fats within these cells
• -These fats are mixed with cholesterol and coated with protein, forming molecules called chylomicrons, which are transported into lacteals
• -Amino acids and sugars pass through the epithelium of the small intestine and enter the bloodstream
• -Capillaries and veins from the lacteals converge in the hepatic portal vein and deliver blood to the liver and then on to the heart

• -The colon of the large intestine is connected to the small intestine
• -The cecum aids in the fermentation of plant material and connects where the small and large intestines meet
• -The human cecum has an extension called the appendix, which plays a very minor role in immunity
• -A major function of the colon is to recover water that has entered the alimentary canal
• -Wastes of the digestive tract, the feces, become more solid as they move through the colon
• -Feces pass through the rectum and exit via the anus
• -The colon houses strains of the bacterium Escherichia coli, some of which produce vitamins
• -Feces are stored in the rectum until they can be eliminated
• -Two sphincters between the rectum and anus control bowel movements

Process of getting rid of materials that were not absorbed and thus were not used for any metabolic activities.  Occurs via defecation.  Not to be confused with excretion.

• -Dental adaptations
• -Stomach and Intestinal Adaptations
• -Mutualistic adaptations
• -Energy Sources and Storage

• -Dentition, an animal’s assortment of teeth, is one example of structural variation reflecting diet
• -Mammals have varying dentition that is adapted to their usual diet
• -The teeth of poisonous snakes are modified as fangs for injecting venom
• -All snakes can unhinge their jaws to swallow prey whole

Herbivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation

• -Many herbivores have fermentation chambers, where symbiotic microorganisms digest cellulose
• -The most elaborate adaptations for an herbivorous diet have evolved in the animals called ruminants

• -Nearly all of an animal’s ATP generation is based on oxidation of energy-rich molecules: carbohydrates, proteins, and fats
• -Animals store excess calories primarily as glycogen in the liver and muscles
• -Energy is secondarily stored as adipose, or fat, cells
• -When fewer calories are taken in than are expended, fuel is taken from storage and oxidized

• -In small and/or thin animals, cells exchange materials directly with the surrounding medium
• -In most animals, transport systems connect the organs of exchange with the body cells
• -Most complex animals have internal transport systems that circulate fluid

• -Simple animals, such as cnidarians, have a body wall that is only two cells thick and that encloses a gastrovascular cavity
• -Gastrovascular cavities function in both digestion and distribution of substances throughout the body

• -A circulatory fluid (blood or hemolymph)
• -A set of tubes (blood vessels)
• -A muscular pump (the heart)

• -In an open circulatory system, there is no distinction between blood and interstitial fluid and this general body fluid is called hemolymph
• -In an open circulatory system blood bathes the organs directly (Ex. in insects, other arthropods, and most mollusks)

• -In a closed circulatory system, blood is confined to vessels and is distinct from the interstitial fluid
• -Closed systems are more efficient at transporting circulatory fluids to tissues and cells.

• -The three main types of blood vessels are arteries, veins, and capillaries
• -Arteries branch into arterioles and carry blood to capillaries
• -Networks of capillaries called capillary beds are the sites of chemical exchange between the blood and interstitial fluid
• -Venules converge into veins and return blood from capillaries to the heart
• -Vertebrate hearts contain two or more chambers
• -Blood enters through an atrium and is pumped out through a ventricle

• -In single circulation, blood leaving the heart passes through two capillary beds before returning
• -Bony fishes, rays, and sharks have single circulation with a two-chambered heart

• -Oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart
• -Amphibian, reptiles, and mammals have double circulation
• -In reptiles and mammals, oxygen-poor blood flows through the pulmonary circuit to pick up oxygen through the lungs
• -In amphibians, oxygen-poor blood flows through a pulmocutaneous circuit to pick up oxygen through the lungs and skin
• -Oxygen-rich blood delivers oxygen through the systemic circuit
• -Double circulation maintains higher blood pressure in the organs than does single circulation

• -Have a three-chambered heart: two atria and one ventricle
• -The ventricle pumps blood into a forked artery that splits the ventricle’s output into the pulmocutaneous circuit and the systemic circuit
• -Underwater, blood flow to the lungs is nearly shut off

• -Have a three-chambered heart: two atria and one ventricle
• -In alligators, caimans, and other crocodilians a septum divides the ventricle
• -Reptiles have double circulation, with a pulmonary circuit (lungs) and a systemic circuit

• -Have a four-chambered heart with two atria and two ventricles
• -The left side of the heart pumps and receives only oxygen-rich blood, while the right side receives and pumps only oxygen-poor blood
• -Mammals and birds are endotherms and require more O2 than ectotherms
• -The mammalian cardiovascular system meets the body’s continuous demand for O2

• -Blood begins its flow with the right ventricle pumping blood to the lungs
• -In the lungs, the blood loads O2 and unloads CO2
• -Oxygen-rich blood from the lungs enters the heart at the left atrium and is pumped through the aorta to the body tissues by the left ventricle
• -The aorta provides blood to the heart through the coronary arteries
• -Blood returns to the heart through the superior vena cava (blood from head, neck, and forelimbs) and inferior vena cava (blood from trunk and hind limbs)
• -The superior vena cava and inferior vena cava flow into the right atrium

• -The heart contracts and relaxes in a rhythmic cycle called the cardiac cycle
• -The contraction, or pumping, phase is called systole
• -The relaxation, or filling, phase is called diastole

• -The heart rate, also called the pulse, is the number of beats per minute
• -The stroke volume is the amount of blood pumped in a single contraction
• -The cardiac output is the volume of blood pumped into the systemic circulation per minute and depends on both the heart rate and stroke volume
• -Four valves prevent backflow of blood in the heart
• -The atrioventricular (AV) valves separate each atrium and ventricle
• -Tricuspid Valve at the right atrium/ventricle, Bicuspid or mitral valve at the left atriumventricle
• -Semilunar valves at the veins/arteries exiting the ventricles
• -The semilunar valves control blood flow to the aorta and the pulmonary artery
• -The “lub-dup” sound of a heart beat is caused by the recoil of blood against the AV valves (lub) then against the semilunar valves (dup)
• -Backflow of blood through a defective valve causes a heart murmur

• Some cardiac muscle cells are self-excitable, meaning they contract without any signal from the nervous system
• -The sinoatrial (SA) node, or pacemaker, sets the rate and timing at which cardiac muscle cells contract
• -Impulses from the SA node travel to the atrioventricular (AV) node
• -At the AV node, the impulses are delayed and then travel to the Purkinje fibers that make the ventricles contract
• -Impulses that travel during the cardiac cycle can be recorded as an electrocardiogram (ECG or EKG)
• -The pacemaker is influenced by nerves, hormones, body temperature, and exercise

• -Capillaries have thin walls, the endothelium plus its basement membrane, to facilitate the exchange of materials
• -Arteries and veins have an endothelium, smooth muscle, and connective tissue
• -Arteries have thicker walls than veins to accommodate the high pressure of blood pumped from the heart
• -In the thinner-walled veins, blood flows back to the heart mainly as a result of muscle action
• -Velocity of blood flow is slowest in the capillary beds, as a result of the high resistance and large total cross-sectional area
• -Blood flow in capillaries is necessarily slow for exchange of materials

• Blood pressure is the hydrostatic pressure that blood exerts against the wall of a vessel
• -In rigid vessels blood pressure is maintained; less rigid vessels deform and blood pressure is lost
• -Systolic pressure is the pressure in the arteries during ventricular systole; it is the highest pressure in the arteries
• -Diastolic pressure is the pressure in the arteries during diastole; it is lower than systolic pressure
• -A pulse is the rhythmic bulging of artery walls with each heartbeat
• -Blood pressure is determined by cardiac output and peripheral resistance due to constriction of arterioles
• -Vasoconstriction is the contraction of smooth muscle in arteriole walls; it increases blood pressure
• -Vasodilation is the relaxation of smooth muscles in the arterioles; it causes blood pressure to fall
• -Vasoconstriction and vasodilation help maintain adequate blood flow as the body’s demands change
• -The peptide endothelin is an important inducer of vasoconstriction
• -Blood is moved through veins by smooth muscle contraction, skeletal muscle contraction, and expansion of the vena cava with inhalation
• -One-way valves in veins prevent backflow of blood

The pressure in the arteries during ventricular systole; it is the highest pressure in the arteries

The pressure in the arteries during diastole; it is lower than systolic pressure

Rhythmic bulging of artery walls with each heartbeat

Contraction of smooth muscle in arteriole walls; it increases blood

Relaxation of smooth muscles in the arterioles; it causes blood pressure to fall

Important inducer of vasoconstriction

• -The critical exchange of substances between the blood and interstitial fluid takes place across the thin endothelial walls of the capillaries
• -The difference between blood pressure and osmotic pressure drives fluids out of capillaries at the arteriole end and into capillaries at the venule end

• The lymphatic system returns fluid that leaks out in the capillary beds
• -This system aids in body defense
• -Fluid, called lymph, reenters the circulation directly at the venous end of the capillary bed and indirectly through the lymphatic system
• -The lymphatic system drains into veins in the neck
• -Lymph nodes are organs that filter lymph and play an important role in the body’s defense
• -Edema is swelling caused by disruptions in the flow of lymph

Returns fluid that leaks out in the capillary beds

A fluid that reenters the circulation directly at the venous end of the capillary bed and indirectly through the lymphatic system

Organs that filter lymph and play an important role in the body’s defense

• Blood in the circulatory systems of vertebrates is a specialized connective tissue
• -Blood is made of several kinds of cells within a liquid called plasma
• -The cellular elements occupy about 45% of the volume of blood

Blood is made of several kinds of cells within a liquid

• -Blood plasma is about 90% water and contains electrolytes (ionic inorganic salts)
• -Contains plasma proteins which regulate blood pH, osmotic pressure, and viscosity
• -Plasma proteins function in lipid transport, immunity, and blood clotting
• -Suspended in blood plasma are two types of cells:
• --Red blood cells (erythrocytes) transport oxygen
• --White blood cells (leukocytes) function in defense
• -Platelets, a third cellular element, are fragments of cells that are involved in clotting

Third cellular element, are fragments of cells that are involved in clotting

• -Red blood cells, or erythrocytes, are the most numerous blood cells
• -They transport oxygen throughout the body
• -Contain hemoglobin, the iron-containing protein that transports oxygen

Iron-containing protein that transports oxygen

Red Blood Cells

White Blood Cells

• -Five major types of white blood cells, or leukocytes: monocytes, neutrophils, basophils, eosinophils, and lymphocytes
• -Function in defense:  phagocytizing bacteria and debris or by producing antibodies
• -They are found both in and outside of the circulatory system

• Fragments of cells which function in blood clotting
• -When the endothelium of a blood vessel is damaged, the clotting mechanism begins
• -A cascade of complex reactions converts fibrinogen to fibrin, forming a clot
• -A blood clot formed within a blood vessel is called a thrombus and can block blood flow

• -The cellular elements of blood wear out and are replaced constantly
• -Erythrocytes, leukocytes, and platelets all develop from a common source of stem cells in the red marrow of bones
• -The hormone erythropoietin (EPO) stimulates erythrocyte production

Stimulates erythrocyte production

• -Disorders of the heart and the blood vessels
• -Account for more than half the deaths in the United States
• -The proportion of LDL relative to HDL can be decreased by exercise, not smoking, and avoiding foods with trans fats
• -Cholesterol is a major contributor to atherosclerosis
• -Atherosclerosis
• -Heart attack
• -Stroke
• -Low-density lipoproteins (LDLs)
• -High-density lipoproteins (HDLs)
• -Hypertension

High blood pressure, increases atherosclerosis and the risk of heart attack and stroke.  Reduced by dietary changes, exercise, and/or medication

Reduce the deposition of cholesterol; “good cholesterol”

Cause plaque formation; “bad cholesterol”

Death of nervous tissue in the brain, usually from rupture or blockage of arteries in the head

The death of cardiac muscle tissue resulting from blockage coronary arteries

Caused by the buildup of plaque deposits within arteries

The pressure exerted by a particular gas in a mixture of gases

• -A gas diffuses from a region of higher partial pressure to a region of lower partial pressure by diffusion.  Partial pressure is the pressure exerted by a particular gas in a mixture of gases
• -In the lungs and tissues, O2 and CO2 diffuse from where their partial pressures are higher to where they are lower
• -Obtaining O2 from water requires greater efficiency than air breathing
• -Respiratory surfaces vary by animal and can include the outer surface, skin, gills, tracheae, and lungs

• Outfoldings of the body that create a large surface area for gas exchange
• -Ventilation moves the respiratory medium over the respiratory surface
• -Aquatic animals move through water or move water over their gills for ventilation
• -Fish gills use a countercurrent exchange system, where blood flows in the opposite direction to water passing over the gills; blood is always less saturated with O2 than the water it meets.

Moves the respiratory medium over the respiratory surface

Where blood flows in the opposite direction to water passing over the gills; blood is always less saturated with O2 than the water it meets

• -The tracheal system of insects consists of tiny branching tubes that penetrate the body
• -The tracheal tubes supply O2 directly to body cells
• -The respiratory and circulatory systems are separate
• -Larger insects must ventilate their tracheal system to meet O2 demands

Consists of tiny branching tubes that penetrate the body

• -Infolding of the body surface
• -The circulatory system (open or closed) transports gases between the lungs and the rest of the body
• -The size and complexity of lungs correlate with an animal’s metabolic rate

• -Air inhaled through the nostrils passes through the pharynx via the larynx, trachea, bronchi, bronchioles, and alveoli, where gas exchange occurs
• -Exhaled air passes over the vocal cords to create sounds
• -Secretions called surfactants coat the surface of the alveoli

The process that ventilates the lungs, the alternate inhalation and exhalation of air

Ventilates its lungs by positive pressure breathing, which forces air down the trachea

• Ventilate their lungs by negative pressure breathing, which pulls air into the lungs
• -Lung volume increases as the rib muscles and diaphragm contract
• -The tidal volume is the volume of air inhaled with each breath

• Have eight or nine air sacs that function as bellows that keep air flowing through the lungs
• -Air passes through the lungs in one direction only
• -Every exhalation completely renews the air in the lungs

• In humans, the main breathing control centers are in two regions of the brain, the medulla oblongata and the pons
• -The medulla regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid
• -The medulla adjusts breathing rate and depth to match metabolic demands
• -The pons regulates the tempo
• -Sensors in the aorta and carotid arteries monitor O2 and CO2 concentrations in the blood
• -These sensors exert secondary control over breathing

Medulla oblongata and the pons

• -Adjusts breathing rate and depth to match metabolic demands
• -Regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid

Regulates the tempo

• -Respiratory pigments, proteins that transport oxygen, greatly increase the amount of oxygen that blood can carry
• -Arthropods and many molluscs have hemocyanin with copper as the oxygen-binding component
• -Most vertebrates and some invertebrates use hemoglobin contained within erythrocytes

Proteins that transport oxygen, greatly increase the amount of oxygen that blood can carry

• -A single hemoglobin molecule can carry four molecules of O2
• -Hemoglobin also helps transport CO2 and assists in buffering
• -CO2 from respiring cells diffuses into the blood and is transported either in blood plasma, bound to hemoglobin, or as bicarbonate ions (HCO3–)

• -Active regulation of osmotic pressure of body fluids to keep them from becoming too dilute or too concentrated
• -Maintain osmotic balance between intracellular and extracellular fluids

Process of riding body of metabolic wastes, including excess water

• -water balance
• -solute balance
• -elimination of metabolic wastes (nitrogenous) -elimination of contaminants & poisons

• -Main wastes of animals are water, carbon dioxide, and nitrogenous waste
• -Water and carbon dioxide are by products of cellular respiration

• C₆H₁₂O₆+O₂CO₂+H₂0+ATP
• Glucose                     Energy

• -Recall, proteins digested into amino acids
• -during metabolism of amino acids, amino group removed, forming ammonia
• -must be immediately expelled (aquatic animals) or converted to safer form
• -uric acid(birds, many reptiles, insects)
• -urea(mammals, most amphibians, marine fishes and turtles)

• -Filtration of blood or body fluids (nonselectively forces water and small solutes into excretory system, but retains proteins & other large molecule in the blood)
• -solution in the excretory system is referred to as the filtrate
• -urine produced from the filtrate by 2 processes:
• --1) reabsorption
• --2) secretion

Blood or body fluids (nonselectively forces water and small solutes into excretory system, but retains proteins & other large molecule in the blood)

Solution in the excretory system

Selective transport of water and essential solutes back into the body fluids

Removal of solutes from body fluids into the excretory system

• -Network of closed tubules that lack internal openings but contain external (nephridiopore)
• -found in invertebrates without circ. Systems
• -interstitial fluid pulled into bulbous cell (flame cell)
• -waste/excess fluid expelled out pore

Interstitial fluid pulled into bulbous cell

• -System of closed tubules that are open at both ends and closely associated with a network of capillaries
• -found in invertebrates with closed circulatory systems
• -nephrostome-inner end which opens into coelem (body cavity); funnels fluid in tube; ciliated funnel
• -fluid moves through tubule -any needed material (salts, wastes, etc) removed by capillaries
• -waste products excreted thru nephidiopore

Inner end which opens into coelom (body cavity); funnels fluid in tube; ciliated funnel

• -Found in insects (open circ. System)
• -closed end of tubule rests in body cavity
• -other end opens into digestive tract
• -waste, solutes, etc. pass from hemolymph into tubule (active transport) and excreted into digestive tract
• -any solutes needed are reabsorbed
• -excreted as uric acid

• -human body has ~5 L of blood, however 1000- 1500 mL/min of blood pass through kidneys
• -nephrons only extract ~180 L/day (45 gal) of filtrate(water, urea, minerals, nutrients) awe excrete ~1.5 L of urine per day
• -bladder capable of holding 800mLof urine (average around 1/2 L

• -Concentration gradient established along renal tubule
• -1) Na ions actively transported out of prox. tubule; water follows due to osmotic pressures
• -2) loop of Henle provided high conc. gradient in medulla

• -Functional unit of the kidney
• -each kidney has > 1 million nephrons -consists of (in order that filtrate passes thru):
• --1) Bowman’s capsule(contains glomerulus)
• --2) long, partially coiled renal tubule(which contains proximal convoluted tubule, loop of Henle, and distal convoluted tubule)
• --3) leads to collecting duct

• -Blood delivered to kidney by renal artery ar. artery branches into afferent arterioles(conduct blood into capillaries of glomerulus)
• -filtration: blood flows through glomerular capillaries under high pressure; forces >10% of plasma (glomerular filtrate) into Bowman’s capsule
• -filtration due to: 1) high hydrostatic pressure in glomerular capillaries; 2) great amount of coiled glomerular capillaries; 3) fenestrations
• -blood flows into efferent capillaries, then to peritubular capillaries, then to small veins, which lead to renal vein

• -Recall -nephrons extract ~180 L/day (45 gal) of filtrate
• -Approx. 99% of filtrate is reabsorbed (thus, leaving only ~ 1.5 L to be excreted)
• -wastes excreted in filtrate; any necessary glucose, salts, etc. reabsorbed with water
• -simple epithelial tissue lining the renal tubules allows reabsorption(microvilli, or “brush border;” cells with abundant mitochondria)

• -movement of substances into renal tubule (opposite of reabsorption)
• -occurs primarily in distal convoluted tubule region
• -include: potassium, hydrogen, ammonium, drugs, etc.

Regulates permeability of collecting ducts; produced in hypothalamus; secreted by posterior pituitary gland