BIO 311D 2nd Edition Lecture 26 Outline of Last Lecture I Wrap up hormone examples 3 23 and 3 25 II Principles of transport and exchange in animals III How excretory tubules help with homeostasis Outline of Current Lecture I Hormones influence excretory tubules II Where is the respiratory epithelium III Principles of Diffusion IV Counter Current Exchange Current Lecture I Hormones influence excretory tubules A Blood pressure leaky tubules allows for easy exchange B Excretory tubules adapt to environment a Structural adaptations 1 Shape 2 Membrane proteins 3 Cell cell junctions 4 Length of tubule relative to water reabsorption b Physiological Responses under hormone control 1 If blood pressure too low 2 If body dehydrated C Kangaroo rat highly adapted to desert conditions a Kidney produces urine that is five times more concentrated than human s kangaroo rats never have to drink water b Assuming that the length of the kidney tubule evolved due to selection for water conservation rank these mammals from expected longest tubules to shortest tubules 3 2 1 1 Beaver 2 Human 3 Kangaroo Rat D When neurons in the brain s hypothalamus detect an increase in blood solute concentration What conditions could lead to an increase in blood solute conditions dehydration etc the pituitary secretes anti diuretic hormone II ADH ADH in blood circulation causes the transport epithelium in the kidney excretory tubules to be more permeable to water how possibly insert aquaporin aquaporin already located on the membrane receptors then proteins attaches to membrane creating a new aquaporin as a result more water is reabsorbed back into the blood and the urine produced is more concentrated a Explain how ADH thus helps maintain homeostasis of solute water in the blood Blood Solute increased ADH released more aquaporin more reabsorption of water into blood Lower solute concentration b Alcohol inhibits ADH secretion what results Decreases ADH secretion water is not reabsorbed stays in the tubules increase urination E One part of a response to a drop in blood pressure is secretion of aldosterone steroid from adrenal cortex Aldosterone acts on nephron s distal tubules and collecting ducts and makes them reabsorb more Na how possibly passive ion channels or sodium pump from the tubule into the cell Thus Explain water follows solute more water comes in increasing blood pressure a If there is an increase in blood volume and pressure ANP hormone atrial natriuretic peptide inhibits NaCl reabsorption Where is the respiratory epithelium A Why do we need gas exchange What is the gas used for To take in oxygen and removing CO2 B Transport epithelium a Cell blood b Blood external surface C No respiratory system needed a In some animals body wall is so thin that they simply absorb O 2 and release CO2 through their skin b Earthworms are skin breathers they must keep their skin moist segmented worms circulatory system is right near the skin c Many amphibians breathe through their skin Even with gills or lungs there are many capillaries close to the thin moist skin and gas exchange can occur D Respiratory organs in many aquatic animals are gills What happens to the O 2 when it crosses the respiratory epithelium a Into the blood through the capillaries into the circulatory system b Ventilation increases flow of water over gills How does the structure of gills optimize their function E Insects trachea branches of respiratory tubules Don t have oxygen move through the tubules they go directly to the body cells F List some ways that lungs can be structured to maximize gas exchange a b c d e III IV Increase lung size Increase external surface area Increase in expansion of lungs Respiratory epithelium Alveoli In the mammalian lung the respiratory surface is an epithelium lining the inner walls of the alveoli Capillary joins the cell of the alveoli as close as you can possibly get to increase gas exchange III Principles of Diffusion A Factors affecting diffusion a Fick s Law for rate of gas exchange 1 Increase surface area increase diffusion 2 Increase path length diffusion distance decrease diffusion 3 Increase the pressure difference increase diffusion b How can respiratory structures be structured to maximize diffusion 1 Increase surface area 2 Decrease path length 3 Increase in pressure difference on either side of the epithelium c From Fick s law tell how each of the factors would affect the rate of diffusion across a membrane would it 1 Increase diffusion small temp change increase surface area 2 Decrease diffusion large temp change thicker cell membrane 3 Have no change d Lung diseases that affect gas exchange How 1 Emphysema decrease in surface area 2 Fibrosis affect diffusion distance 3 Pulmonary Edema affects diffusion distance Counter Current Exchange A Increases concentration gradient B Water comes in 100 oxygenated blood comes in only 20 oxygenated C More oxygen goes into the blood