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1. What distinguishes osmolarity from tonicity?
total solute concentration, tonicity is cell volume
What are the major functions of the excretory system, other than removal of nitrogenous waste?
Removes excess water to maintain a suitable osmolarity within the tissues and cells.
1. What three forms of nitrogenous wastes are produced by vertebrates? Which forms are produced by humans?
Urea, Uric acid, ammonia
1. List and describe the four stages of urine production.
filtration, reasbsorbtion, excretion,, secretion,
1. Distinguish between cortical and juxtomedullary nephrons in terms of structure and function.
Cortical nephrons have a shorter loop of Henle, while juxtamedullary nephrons have a longer loop of Henle that extends deep into the medulla. Cortical nephrons are responsible for most of the kidney's filtration, while juxtamedullary nephrons play a crucial role in producing concentrated urine.
1. How is glomerular filtration rate controlled? This is a complex question with many different moving parts. Try to create an exhaustive list.
The glomerular filtration rate (GFR) is controlled by various mechanisms, including:
Renal autoregulation: the ability of the kidneys to maintain a constant blood flow and GFR despite changes in blood pressure.
Hormonal regulation: hormones such as angiotensin II, aldosterone, and atrial natriuretic peptide can affect GFR by altering renal blood flow and/or the permeability of the glomerular membrane.
Neural regulation: the sympathetic nervous system can affect GFR by constricting or dilating the afferent arterioles that supply blood to the glomerulus.
Tubuloglomerular feedback: the juxtaglomerular apparatus in the kidney can sense changes in the flow of fluid through the tubules and adjust the resistance of the afferent arterioles accordingly.
Physical factors: the size and charge of the molecules passing through the glomerular membrane can affect GFR, as can the surface area and permeability of the membrane itself.
1. How are the following substances reabsorbed: sodium, water, small anions, glucose?
Sodium is reabsorbed through active transport. Water is reabsorbed through osmosis Small anions are reabsorbed through passive transport in the proximal tubule and loop of Henle. Glucose is reabsorbed through secondary active transport in the proximal tubule.
How are organic anions secreted into the urine
Organic anions are secreted into the urine by renal tubular cells. These transporters move the anions from the blood into the tubular cells and then out into the urine.
1. How do ADH and the RAAS pathway regulate urine osmolarity?
Flashcard:
ADH controls water reabsorption in the collecting ducts by increasing aquaporin channels. RAAS pathway regulates sodium and water reabsorption.
How does the urinary system help regulate blood pH?
Kidneys filter blood and remove excess acids or bases.
Urine pH varies from 4.5-8.0 depending on body's need.
Acidic urine excretes H+ ions and basic urine excretes HCO3- ions.
What is the function of saliva? What enzymes are present in saliva and what are their functions in digestion?
Function of saliva: Moistens food, helps in swallowing, and initiates digestion. Enzymes in saliva: Amylase breaks down carbohydrates, Lipase breaks down fats.
List the secretory cells of the stomach and their major products
Includes parietal cells that produce hydrochloric acid and intrinsic factor, chief cells that secrete pepsinogen, and G cells that release gastrin.
Where in the digestive system do muscles undergo tonic contractions? Why?
Smooth muscles in the walls of the digestive tract undergo tonic contractions. This helps in maintaining the pressure in the digestive tract and prevents the backflow of food.
1. What are slow wave potentials? How do they help set up patterns of peristaltic contractions in the intestine?
Slow wave potentials are rhythmic changes in the resting membrane potential of smooth muscle cells in the digestive tract that help set up patterns of peristaltic contractions, moving food and waste materials along the intestine.
1. Distinguish between peristalic and segmental contractions.
Peristaltic contractions move materials along the digestive tract by sequential contraction of circular and longitudinal muscles, while segmental contractions mix and churn materials in the digestive tract without propelling them in a specific direction.
1. What is the main digestive secretion of the liver? What is its function and how does it work? 2. List two digestive secretions of the pancreas. Where do these products of the pancreas actually carry out their functions?
The main digestive secretion of the liver is bile, which helps in emulsification and absorption of fats in the small intestine.
Two digestive secretions of the pancreas are pancreatic amylase and pancreatic lipase, which function in the small intestine to break down carbohydrates and fats, respectively.
1. List the three phases of digestion. In which phase is gastric secretion initiated? How?
The three phases of digestion are cephalic, gastric, and intestinal phases, and gastric secretion is initiated during the gastric phase through the release of gastrin hormone due to the distension of the stomach by food.
The small intestine releases maltase, which is responsible for breaking down maltose (malt sugar) into glucose (simple sugar). The body uses glucose for energy.Sep 6, 2022
Describe how the following substances are absorbed: glucose, fructose, single amino acids, small peptides, lipids
Glucose and fructose are absorbed through the intestinal wall via facilitated diffusion and then enter the bloodstream . Single amino acids and small peptides are absorbed through the intestinal and lipids are absorbed by being broken down into fatty acids which are then absorbed into the intestinal cells,
1. What are the two forms of metabolism? Which is dominant in a fed state?
The two forms of metabolism are anabolic metabolism and catabolic metabolism.
Anabolic metabolism is dominant in the fed state, as it involves the synthesis of larger molecules from smaller molecules because of food Catabolic metabolism, on the other hand, is dominant in the fasted state and involves the breakdown of larger molecules into smaller molecules, because of no food
What is basal metabolic rate? Why is this difficult to measure? What is typically measured instead
The BMR refers to the amount of energy your body needs to maintain homeostasis
1. What distinguishes direct and indirect calorimetry? Give three examples of how indirect calorimetry can be performed.
Direct calorimetry measures heat production directly by measuring the amount of heat generated by a living organism.
Portable metabolic carts
Room calorimeters
Doubly labeled water
1. List five factors that can cause changes in metabolic rate of an individual animal and the effect those factors have.
body size, age,physical activity, environmental temperature, nutritin
How does metabolic rate scale with body size in most animals
the smaller the organism's mass, the higher its basal metabolic rate is likely to be.
1. List the two major categories of energy outputs. Under each, what is energy used for?
Note
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