Lecture_26_Digestion_and_Renal_Lecture 2.pptx

GENERAL BIOLOGY II Lecture 25: Digestive System & Metabolism (cont.) Chapter: 38 Specialized Regions of the Gut Specialized Regions of the Gut To get nutrients from the environment, two activities have to take place: Digestion – Absorption – Specialized Regions of the Gut To get nutrients from the e...

GENERAL BIOLOGY II Lecture 25: Digestive System & Metabolism (cont.) Chapter: 38 Specialized Regions of the Gut Specialized Regions of the Gut To get nutrients from the environment, two activities have to take place: Digestion – Absorption – Specialized Regions of the Gut To get nutrients from the environment, two activities have to take place: Digestion – breaking down food into smaller components Absorption – transferring the broken down products into the bloodstream Specialized Regions of the Gut Most animal digestive tracts are broken into three distinctive parts: Specialized Regions of the Gut Most animal digestive tracts are broken into three distinctive parts: Foregut Midgut Hindgut Specialized Regions of the Gut Most animal digestive tracts are broken into three distinctive parts: Foregut Midgut Hindgut Specialized Regions of the Gut Foregut includes: Mouth Esophagus Stomach (or crop) Foregut Digestion begins in the mouth: Mechanical breakdown of food Some animals also begin chemical digestion in the mouth Amylase – breakdown carbs. Lipase – breakdown lipids Foregut Mouth Pharynx Esophagus Pharynx – connects the mouth and nasal cavity to the throat Epiglottis – which prevents food / water from entering the trachea Esophagus – connects pharynx to the stomach Epiglottis Foregut Birds, crocodilians, and earthworms have a gizzard, which helps break down food into smaller pieces Birds and earthworms often ingest small rocks to store in the gizzard to help with the grinding of food. Foregut Additional digestion takes place in the stomach: Main site of protein and lipid breakdown Has a low pH (1 – 3); HCl (acid) Gastrin – hormone that regulates stomach acid production; controlled by a negative feedback loop Foregut The stomach protects itself from the acid an digestive enzymes in two ways: Cells of the stomach lining secrete mucus to create a barrier to the acid Digestive enzymes are secreted in an inactive form that is activated by the stomach acid Foregut The primary digestive enzyme in the stomach is pepsin: Secreted as inactivated pepsinogen Breaks down proteins into amino acids Lipases are also secreted, which break down lipids Foregut Food in various stages of digestion is physically moved through the stomach by Peristalsis waves of contraction and relaxation by smooth muscle surrounding the organ Foregut Foregut Chime is moved to the pyloric sphincter in the stomach, which is a muscular ring that opens to the small intestine. There partially digested food moves out of the foregut and into the midgut. Midgut The first part of the midgut is the duodenum. Aided by the gallbladder and the pancreas Pancreas secretes bicarbonate to neutralize stomach acid, and digestive enzymes, including trypsin, which breaks down proteins Midgut Pancreas: Bicarb release is controlled by the hormone secretin, which are released when the pH drops in the duodenum Midgut Gallbladder: Stores bile, which is made by the liver, and breaks up fats into smaller droplets in a process called emulsification Bile release is controlled by the hormone cholecystokinin (CCK), which is released when fats enter the duodenum Midgut Small intestine Covered with folds and fingerlike projections called villi Cells in the villi end in tiny, microscopic projections called microvilli All of this is to maximize surface area for absorption of nutrients Midgut Small intestine Glucose (and other hydrophilic nutrients) are co-transported into the intestinal cells with Na+ Passive glucose transport proteins then facilitate the movement of glucose into the blood stream in an adjacent capillary Midgut Small intestine Hydrophobic nutrients, like fats, passively move through the intestinal cell membranes, and eventually bind with molecules to make them water soluble as they reach the blood in the capillary Hindgut Large intestine Absorption of water Absorption of inorganic nutrients (minerals) Elimination of waste (feces) GENERAL BIOLOGY II Lecture 25: Renal System Chapter: 41 Renal System Purpose: Osmoregulation Elimination of nitrogenous waste products Renal System Purpose: Osmoregulation – balancing water and solutes within the body Elimination of nitrogenous waste products Renal System Vocabulary: Solutes – dissolved molecules (electrolytes, sugars, etc.) Osmosis – the diffusion of water Osmotic Pressure – the tendency of water to move from one area to another. The greater the difference in solute concentration, the higher the pressure is for water to move towards the solutes Renal System Renal System Vocabulary: Selectively Permeable – a membrane that allows some molecules through it, but not others. Membranes are often water permeable. Aquaporins – channels in a lipid bilayer membrane that allow water to move through it. Renal System Osmoconformers – Keep internal fluids at the same osmotic pressure of the environment Osmoregulators – Maintain internal fluids at a stable osmotic pressure that is distinct from that of the environment Renal System Renal System Cornell Lab; All About Birds allaboutbirds.org, 2024 Nitrogenous Waste Removal When proteins and nucleic acids are broken down, ammonia (NH3) is produced Ammonia is toxic to living cells Nitrogenous Waste Removal Different organisms deal with ammonia production in different ways Ammonia – most toxic, requires high volumes of water Urea – less toxic, but requires energy to produce and water to eliminate Uric Acid – Least toxic, energetically most expensive Nitrogenous Waste Removal Nitrogenous wastes from the blood through two mechanisms: Filtration – blood is passed into an extracellular space, but some substances are prevented from returning to a blood vessel Secretion – active transport of substances from blood into an extracellular space Nitrogenous Waste Removal Reabsorption – process by which essential molecules are transported back into blood after filtration Nitrogenous Waste Removal Different animals have different excretory organs. Invertebrates have many different systems. All vertebrates have paired kidneys. In the interest of time, we’re only going to focus on the mammalian kidney. The Mammalian Kidney Kidneys: Filter nitrogenous waste Help regulate blood pressure / blood volume The Mammalian Kidney Kidney Anatomy Renal artery brings blood into the kidney Filtrate is collected in the renal pelvis Filtered blood is returned via the renal vein The ureter leads to the urinary bladder The Mammalian Kidney Kidney Anatomy The filtration takes place in the Renal Pyramids The renal pyramids are filled with Nephrons, which are renal tubules along with associated capillaries The Mammalian Kidney Kidney Anatomy The outer layer of the kidney is called the cortex The inner layer is called the medulla Further subdivided into the inner and outer medulla The Mammalian Kidney Kidney Anatomy Glomerulus – tuft of capillaries inside the membranous sac called a Bowman’s capsule Individual renal tubules in a renal pyramid flow into a collecting duct The Mammalian Kidney The Bowman’s Capsule: Location where blood is first filtered for water, waste, and solutes Move from capillary into the Bowman’s space The Mammalian Kidney Renal tubules are divided into: Proximal convoluted tubule Loop of Henle Distal convoluted tubule The Mammalian Kidney Proximal convoluted tubule Electrolytes, glucose, amino acids, sodium and chloride are reabsorbed into the blood To increase surface area, this region is lined with microvilli The Mammalian Kidney Loop of Henle Descending side is water permeable Ascending side is water impermeable, and actively transports electrolytes out The Mammalian Kidney Loop of Henle The blood vessels flow in opposite directions of the solute in the loop of Henle This sets up a counter current exchange, so blood is always able to accept more water here The Mammalian Kidney Distal convoluted tubule Main site of secretion Waste not filtered by the glomerulus is actively added here Regulates K+, Na+, and Ca+2 Regulates urine pH with bicarbonate The Mammalian Kidney Collecting Duct Permeability is regulated by antidiuretic hormone (ADH) ADH is secreted by the posterior pituitary to control the amount of water in the body The Mammalian Kidney Controlling Blood Pressure Because the so much blood flows through the kidney, it’s an ideal location to monitor blood pressure Specialized cells (juxtaglomerular apparatus) in the blood vessels leaving the glomerulus detect low or high blood pressure The Mammalian Kidney Controlling Blood Pressure When blood pressure is low, the juxtaglomerular apparatus trigger the hormone angiotensin to be activated, which causes smooth muscles in the blood vessels to contract, which raises blood pressure They also signal aldosterone to be released from the adrenals, which increases reabsorption in the collecting ducts, which increases blood volume (and pressure) For Next Class Complete the Quiz on CANVAS Chapter 39: Reproduction & Development