Learning Objectives Flashcards
Contrast the three forms of nitrogenous waste excreted by animals, in terms of toxicity, solubility, and chemical composition. Cite the advantages and disadvantages of excreting each.
- Ammonia: most toxic, soluble in water, consumes very little energy, excreted in a dilute solution, During breakdown of proteins, amino groups are stripped from amino acids. Each amino group picks up a hydrogen ion and becomes ammonia.
- Urea: higher concentration of nitrogen than ammonia, Less toxic, requires less dilution, helps conserve water. Mammals, adult frogs and toads, turtles, and cartilaginous fishes form urea, which the liver produces as cells break down proteins. Eliminated with water in urine.
- Uric acid: higher concentration of nitrogen than ammonia, Less toxic, requires less dilution, helps conserve water. Insects, land tortoises lizards and birds. Insoluble in water, excreted in solid form. Loses the least amount of water. Eliminated through undigested food.
Contrast the anatomy of the excretory systems of humans and insects (32.3 and 32.4). In the insect’s Malpighian tubules and the human’s urinary system, describe the relationship of nitrogenous waste to feces and the gut.
Insects have a malphigian tubule and humans do not.
Nitrogenous gases are released in urine in humans. The kidney eliminates urea. Insects excrete uric acid in a solid form though undigested food.
Trace the processing of filtrate through the nephron of a human kidney, including the glomerulus, Bowman’s capsule, proximal convoluted tubule, descending and ascending portions of the loop of Henle, distal convoluted tubule, and the collecting duct (32.5A, C-E).
Nephron: The functional units of the kidney. Each nephron is entertained with a network of capillaries. Consists of two main parts:
- Glomerular capsule: Located in the kidney’s outer portion, or cortex. Surrounds the glomerulus. Receives blood from the Glomerulus (Tuft of capillaries where blood is filtered into the nephron. The capillaries converge into another arteriole. Pores allow water, urea, glucose, salts, amino acids, and creatinine to pass into glomerular capsule.)
- Renal tubule: The solution from the glomerular (Bowman’s) capsule travels along the renal tubule, which are winding passageways consisting of three functional regions:
- Proximal convoluted tubule: Part of the renal tubule of a nephron. Leads from the glomerular capsule to the hairpin-shaped nephron loop. Selective reabsorption and secretion occurs here. Work together to maintain a pH of blood between 7 and 8.
- The nephron loop: Part of the renal tubule of a nephron. Hair-shaped turn into the medulla. The descending limb of the nephron loop dips into the renal medulla toward the kidney’s center and the ascending limb returns to the distal convoluted tubule. The filtrate flows in the opposite direction of the blood in surrounding capillaries.
- Distal convoluted tubule: The ascending part of the nephron loop returns here. Sodium ions and CI- ions move out of the filtrate and into the blood by active transport. Once filtrate has passed here 97% of water in the original glomerular filtrate has been reabsorbed and little salt remains.
Each kidney receives blood via a renal artery, which branches into multiple arteries and arterioles. An arteriole delivers blood to a glomerulus, a tuft of capillaries where blood is filtered into the nephron. The capillaries of the glomerulus then converge into another arteriole, which leads to the peritubular capillaries that snake around part of each nephron. These blood vessels empty into a venule, which joins the renal vein carrying cleansed blood out of the kidney and (ultimately) to the heart.
Collecting duct: Receives the fluid from several nephrons. Urine accumulates in the funnel-like renal pelvis before entering the ureter and urinary bladder and moving out of the body through the urethra. Remaining water leaves here by osmosis.
Explain the effects on urine production of antidiuretic hormone (ADH), ethyl alcohol and caffeine (32.5F).
ADH: A peptide hormone that triggers the formation of additional water channels in the walls of the distal convoluted tubule and collecting duct. As a result, the blood reabsorbs more water and the urine becomes very concentrated.
ADH allows the blood to reabsorb more water making the urine more concentrated
Ethyl alcohol stimulates urine production by reducing ADH secretion, thereby decreasing the permeability of the tubules to water which intensifies thirst.
Aldosterone: Steroid hormone that stimulates the production of sodium channels in the distal convoluted tubule.
Compare a kidney dialysis machine with a normal kidney
The dialysis machine pumps blood out of the patient’s body and past a semipermeable membrane. Wastes and toxins, along with water, diffuse
across the membrane to a waste fluid called “dialysate,” but blood cells do not. The cleaned blood then circulates back to the patient’s body.
Dialysis membranes cannot replace all of the kidney’s functions.
For example, nephrons selectively recycle useful components such as
glucose and salts to the blood. The dialysis machine cannot do this,
although a technician can adjust the concentrations of these dissolved
compounds in the dialysate to promote or inhibit diffusion from the
blood.
Given a description of one of several kidney diseases, name the disease.
Diabetes: More than a trace of glucose may be a sign of diabetes,
a high-carbohydrate diet, or stress. Stress causes the
adrenal glands to release excess epinephrine, which
stimulates the liver to break down more glycogen into
glucose.
Albumin: may be a sign of damaged nephrons, since this
plasma protein does not normally fit through the pores of
intact glomerular capsules.
Urinary tract infection: Pus and an absence of glucose indicate a urinary tract infection. The pus consists of infection-fi ghting white blood cells along with bacteria, which consume the glucose.
List four things necessary for gas exchange to occur in multicellular animals and explain why each is required (Lab Guide, Minicourse 2, p. 2).
- Concentration gradient: diffusion can occur only down a concentration gradient. High concentration to an an area of lower concentration. The concentration of oxygen outside the cell has to be greater than it is inside.
- Moist membranes
- Surface area must be adequately large to meet the needs of the entire organism.
- Internal transport system: needed for efficient movement of gases to and from the inner body cells.
Describe how the efficiency of gas exchange and gas transport have been improved by hemoglobin, red blood cells, branched gas exchanges surfaces, and internal transport systems.
Hemoglobin: ron-rich pigment protein that binds with O2. Can carry up to 4 O2 molecules.
Red blood cells: Transports the rest of the O2 not dissolved by plasma. Contains hemoglobin.
Describe how the respiratory surfaces of unicellular organisms, insects, fish and animals (30.1 and figure 30.2) maintain an adequate surface area to volume ratio for gas exchange.
Area of animal’s body where external expiration occurs.
Humans: lungs
Shares three characteristics:
- Surface area must be large
- Must come into contact with either air or water. Air has a higher concentration of O2 and is lighter so less energy is required to move air across a respiration surface.
- Consist of moist membranes across which O2 and CO2 diffuse.
Compare and contrast the structural organization and gas exchange efficiency of gills and lungs. Include the availability of oxygen in water and air, countercurrent flow in gill filaments, and the structure of the alveolar sacs in lungs (30.1B,C and 30.2).
Concurrent exchange: two adjacent currents flow in opposite directions and exchange materials with each other.
Gills: highly folded structures containing blood vessels that exchange gases with waster across a thin layer of epithelium.
Capillaries: The tiniest of blood vessels. Each filament includes platelike lamellae that house a dense network of capillaries. The direction of water flow across lamellae opposes that of blood flow in the capillaries. The concurrent relationship maximizes gas exchange between water and blood.
Lungs: Saclike organs that exchange gases. Homologous to the gas bladders of bony fish.
Given a description of one of several lung diseases, name the disease. (p. 629; Lab Guide #2).
Asthma: spasms occur in the smooth muscle lining in the lung’s bronchi slowing airflow and causing wheezing.
Lung cancer: chemicals mutate DNA in lung cells; these cells may divide and form tumors. Chest pain, chronic coughing, and shortness of breath.
Apnea: cessation of the breathing. The fleshy folds of the throat sag into the airway, causing breathing to stop for a short time.
Pneumonia: inflammation of the alveoli, usually resulting from an infection. Symptoms: green or yellow mucus, fever, chest pain, coughing and shortness of breath.
Common cold: infect the upper respiratory tract. Coughs, runny nose and sneezes.
Tuberculosis: infection of the bacterium Mycobacterium tuberculosis. Symptoms: painful coughs, bloody phlegm, fever and weight loss.
Emphysema: loss of elasticity in lung tissue. The walls of the alveioli tear, impeding airflow and reducing the surface area for gas exchange. Shortness of breath, an expanded chest, and hyperventilation.
Cystic fibrosis: faulty transport protein in the membranes of epithelial cells cause sticky mucus to accumulate in the lungs. Thick mucus prevents cilia from beating.
Explain how the efficiency of animal circulatory systems has been improved by the evolution of internal body cavities, open circulatory systems, closed circulatory systems, respiratory pigments, atria and ventricles (29.3)
Open circulatory system: Heart pumps fluid through short, open-ended vessels. Vessels lead to open spaces in the body cavity, where the fluid can exchange materials with the body’s cells. Fluid enters other vessels leading back to the heart. Mollusks and arthropods. Requires fewer vessels, moves under low pressure.
Closed circulatory system: Blood remains within vessels that exchange materials with the fluid surrounding the body’s tissues. Vertebrates, annelids and cephalopod mollusk. Blood moves at a higher pressure so nutrient delivery and waste removal occur more rapidly. Can direct blood flow toward and away from specific areas. More efficient.
Arteries: Large vessels that conduct blood away from the heart
Arterioles: Branched from arteries. Smaller vessels than then diverge into a network of capillaries.
Capillaries: Branched from arterioles. The body’s tiniest blood vessels. Empties into venules.
Interstitial fluid: Liquid that bathes the body’s cells. Exchanges materials with the tissue cells.
Venules: Branched from capillaries. Slightly larger vessels which unite to form the veins.
Veins: Formed by venules. Carries blood back to the heart.
Given a diagram of the human heart, label its structures (including chambers, valves and major blood vessels) and trace the flow of blood through the heart (29.4 A,B)
Superior and inferior vena cava deliver blood from the systemic circulation to the right atrium. Blood then passes into the right ventricle and through the pulmonary arteries to the lungs where blood picks up O2 and unloads CO2. The pulmonary veins carry oxygen-rich blood from the lungs to the left atrium of the heart.
Explain how the pumping efficiency of the vertebrate heart has been improved by the evolution of: atria, the AV node, the SA node, the bundle of His, the separation of right and left ventricles, atrioventricular valves and semilunar valves (29.4 B,C).
Left and right atria: Left receives oxygen rich blood from the lungs. Right receives oxygen depleted blood from the rest of the body. Blood from both atria mixes in the ventricles which pumps the blood throughout the body.
SA node: Region of specialized cardiac muscle cells in the upper wall of the right atrium. Pacemaker. When cells fire, they stimulate the cardiac cells of the atria to contract.
AV valve: Thin flaps of tissue that prevent blood from moving back into the atrium when the ventricle contracts.
Semilunar valve: Prevent backflow into the ventricles from the arteries leaving the heart. 3
Correlate the features of a normal, human electrocardiogram (ECG) with the events associated with one heartbeat: heart sounds and the status of the chambers and valves (Figure 29.10).
- Starts at the Sinoatrial (SA) node
- SA node cells fire stimulating the cardiac cells of the atria to contract.
- Electrical impulses race across the atrial wall to the AV node
- The ventricles have time to fill, the AV node conducts electrical stimulation throughout the ventricle walls. The cardiac cells of the ventricles contract in unison.
Lup dup sound comes from the two sets of valves closing, preventing backflow of blood.
Lub: closing of the AV valve
Dup: closing of the semilunar valves during ventricle relaxation
P: contraction of the atria
QRS: contraction of the ventricles
T: relaxation of the ventricles.
Large QRS: relaxation of the atria
