Lecture 35 – Controlling the Internal Environment

Lecture 35 – Controlling the Internal Environment

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Lecture 35 – Controlling the Internal Environment Not called secretion/absorption, called controlling the internal environment Osmoconformers – wherever they’re at is their osmotic pressure (is they live in the ocean, it is that of the ocean) Osmoregulation – needs to control their osmotic balance (you have a certain amount of osmotic pressure that needs to be kept fairly constant) A. Introduction 1. Complex animals – osmoregulation and excretion are carried out by the excretory system (the kidney in us) 2. Osmoregulation 3. Excretion – getting rid of metabolic waste 4. Elimination – getting rid of digestive waste; such as cellulose B. Metabolic wastes a. Carbon dioxide – the lungs get rid of most of your carbon dioxide b. Nitrogenous wastes (come from broken down proteins and nucleic acids) - Ammonia (fig 46.1) – takes very little energy (just taking the nitrogen and getting rid of it, not metabolizing it any further); Ex: fish (lots of water to dilute the toxic ammonia) – ammonia is the most toxic thing listed - Uric acid – most complex, but least toxic; requires a lot of energy; birds (can’t have a lot of water because they fly) and reptiles (want to conserve water); non toxic to the eggs - Urea – a little more complex than ammonia and requires a little more energy (less toxic); requires more water than uric acid and a lot let water than ammonia; Ex: amphibians and mammals C. Osmoregulatory Organs 1. Simple diffusion (protozoa and sponges rid of their waste this way); contractile vacuoles – water regulation; ( some freshwater protozoa, because freshwater is hypotonic compared to the organism) 2. Nephridial organs (figs. 46.2, 46.3) - Protonephridia – the flatworms (like planaria); means “first kidney;” considered a blind tubule and there is a flame cell; used mostly for water balance, most wastes go out my simple diffusion so urine doesn’t come out ( it is hypotonic, dilute, compared to the organism) - Metanephridia – annelids, tube that is open on both ends (one end is ciliated, good things (glucose) and waste (urea) goes into it; good things get reabsorbed and wastes get sent out, the urine is hypotonic); our urine is hypertonic
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