44 excretion text

Chapter 44 Osmoregulation and Excretion

[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Figure 44.1

[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object]

Osmosis ,[object Object],[object Object],[object Object],[object Object]

Osmotic Challenges ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Figure 44.2

Marine Animals ,[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Figure 44.3a (a) Osmoregulation in a saltwater fish Gain of water and salt ions from food and by drinking seawater Osmotic water loss through gills and other parts of body surface Excretion of salt ions from gills Excretion of salt ions and small amounts of water in scanty urine from kidneys

Freshwater Animals ,[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Figure 44.3b (b) Osmoregulation in a freshwater fish Uptake of water and some ions in food Osmotic water gain through gills and other parts of body surface Uptake of salt ions by gills Excretion of large amounts of water in dilute urine from kidneys

Animals That Live in Temporary Waters ,[object Object],[object Object],[object Object],Figure 44.4a, b (a) Hydrated tardigrade (b) Dehydrated tardigrade 100 µm 100 µm

Land Animals ,[object Object],[object Object],Figure 44.5 Water balance in a human (2,500 mL/day = 100%) Water balance in a kangaroo rat (2 mL/day = 100%) Ingested in food (0.2) Ingested in food (750) Ingested in liquid (1,500) Derived from metabolism (250) Derived from metabolism (1.8) Water gain Feces (0.9) Urine (0.45) Evaporation (1.46) Feces (100) Urine (1,500) Evaporation (900) Water loss

[object Object],[object Object],Figure 44.6 Control group (Unclipped fur) Experimental group (Clipped fur) 4 3 2 1 0 Water lost per day (L/100 kg body mass) Knut and Bodil Schmidt-Nielsen and their colleagues from Duke University observed that the fur of camels exposed to full sun in the Sahara Desert could reach temperatures of over 70°C, while the animals’ skin remained more than 30°C cooler. The Schmidt-Nielsens reasoned that insulation of the skin by fur may substantially reduce the need for evaporative cooling by sweating. To test this hypothesis, they compared the water loss rates of unclipped and clipped camels. EXPERIMENT RESULTS Removing the fur of a camel increased the rate of water loss through sweating by up to 50%. The fur of camels plays a critical role in their conserving water in the hot desert environments where they live. CONCLUSION

Transport Epithelia ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],Figure 44.7a, b Nasal salt gland Nostril with salt secretions Lumen of secretory tubule NaCl Blood flow Secretory cell of transport epithelium Central duct Direction of salt movement Transport epithelium Secretory tubule Capillary Vein Artery (a) An albatross’s salt glands empty via a duct into the nostrils, and the salty solution either drips off the tip of the beak or is exhaled in a fine mist. (b) One of several thousand secretory tubules in a salt- excreting gland. Each tubule is lined by a transport epithelium surrounded by capillaries, and drains into a central duct. (c) The secretory cells actively transport salt from the blood into the tubules. Blood flows counter to the flow of salt secretion. By maintaining a concentration gradient of salt in the tubule (aqua), this countercurrent system enhances salt transfer from the blood to the lumen of the tubule.

[object Object],[object Object],Figure 44.8 Proteins Nucleic acids Amino acids Nitrogenous bases – N H 2 Amino groups Most aquatic animals, including most bony fishes Mammals, most amphibians, sharks, some bony fishes Many reptiles (including birds), insects, land snails Ammonia Urea Uric acid N H 3 N H 2 N H 2 O C C C N C O N H H C O N C H N O H

Forms of Nitrogenous Wastes ,[object Object],[object Object]

Ammonia ,[object Object],[object Object],[object Object]

Urea ,[object Object],[object Object],[object Object],[object Object]

Uric Acid ,[object Object],[object Object],[object Object],[object Object]

The Influence of Evolution and Environment on Nitrogenous Wastes ,[object Object],[object Object],[object Object],[object Object]

Excretory Processes ,[object Object],[object Object],Figure 44.9 Filtration. The excretory tubule collects a filtrate from the blood. Water and solutes are forced by blood pressure across the selectively permeable membranes of a cluster of capillaries and into the excretory tubule. Reabsorption. The transport epithelium reclaims valuable substances from the filtrate and returns them to the body fluids. Secretion. Other substances, such as toxins and excess ions, are extracted from body fluids and added to the contents of the excretory tubule. Excretion. The filtrate leaves the system and the body. Capillary Excretory tubule Filtrate Urine 1 2 3 4

Survey of Excretory Systems ,[object Object],[object Object],[object Object]

Protonephridia: Flame-Bulb Systems ,[object Object],[object Object],Figure 44.10 Nucleus of cap cell Cilia Interstitial fluid filters through membrane where cap cell and tubule cell interdigitate (interlock) Tubule cell Flame bulb Nephridiopore in body wall Tubule Protonephridia (tubules)

Metanephridia ,[object Object],[object Object],Figure 44.11 Nephrostome Metanephridia Nephridio- pore Collecting tubule Bladder Capillary network Coelom

[object Object],[object Object]

Malpighian Tubules ,[object Object],[object Object],Figure 44.12 Digestive tract Midgut (stomach) Malpighian tubules Rectum Intestine Hindgut Salt, water, and nitrogenous wastes Feces and urine Anus Malpighian tubule Rectum Reabsorption of H 2 O, ions, and valuable organic molecules HEMOLYMPH

Vertebrate Kidneys ,[object Object],[object Object]

[object Object],[object Object],Figure 44.13a Posterior vena cava Renal artery and vein Aorta Ureter Urinary bladder Urethra (a) Excretory organs and major associated blood vessels Kidney

Structure and Function of the Nephron and Associated Structures ,[object Object],[object Object],(b) Kidney structure Ureter Section of kidney from a rat Renal medulla Renal cortex Renal pelvis Figure 44.13b

[object Object],[object Object],Figure 44.13c, d Juxta- medullary nephron Cortical nephron Collecting duct To renal pelvis Renal cortex Renal medulla 20 µm Afferent arteriole from renal artery Glomerulus Bowman’s capsule Proximal tubule Peritubular capillaries SEM Efferent arteriole from glomerulus Branch of renal vein Descending limb Ascending limb Loop of Henle Distal tubule Collecting duct (c) Nephron Vasa recta (d) Filtrate and blood flow

Filtration of the Blood ,[object Object],[object Object]

Pathway of the Filtrate ,[object Object],[object Object],[object Object],[object Object]

Blood Vessels Associated with the Nephrons ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

From Blood Filtrate to Urine: A Closer Look ,[object Object],[object Object],Figure 44.14 Proximal tubule Filtrate H 2 O Salts (NaCl and others) HCO 3 – H + Urea Glucose; amino acids Some drugs Key Active transport Passive transport CORTEX OUTER MEDULLA INNER MEDULLA Descending limb of loop of Henle Thick segment of ascending limb Thin segment of ascending limb Collecting duct NaCl NaCl NaCl Distal tubule NaCl Nutrients Urea H 2 O NaCl H 2 O H 2 O HCO 3  K + H + NH 3 HCO 3  K + H + H 2 O 1 4 3 2 3 5

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Solute Gradients and Water Conservation ,[object Object],[object Object]

[object Object],[object Object],Figure 44.15 H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O NaCl NaCl NaCl NaCl NaCl NaCl NaCl 300 300 100 400 600 900 1200 700 400 200 100 Active transport Passive transport OUTER MEDULLA INNER MEDULLA CORTEX H 2 O Urea H 2 O Urea H 2 O Urea H 2 O H 2 O H 2 O H 2 O 1200 1200 900 600 400 300 600 400 300 Osmolarity of interstitial fluid (mosm/L) 300

Regulation of Kidney Function ,[object Object],[object Object]

[object Object],[object Object],Figure 44.16a (a) Antidiuretic hormone (ADH) enhances fluid retention by making the kidneys reclaim more water. Osmoreceptors in hypothalamus Drinking reduces blood osmolarity to set point H 2 O reabsorption helps prevent further osmolarity increase STIMULUS: The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood Homeostasis: Blood osmolarity Hypothalamus ADH Pituitary gland Increased permeability Thirst Collecting duct Distal tubule

[object Object],[object Object],Figure 44.16b (b) The renin-angiotensin-aldosterone system (RAAS) leads to an increase in blood volume and pressure. Increased Na + and H 2 O reabsorption in distal tubules Homeostasis: Blood pressure, volume STIMULUS: The juxtaglomerular apparatus (JGA) responds to low blood volume or blood pressure (such as due to dehydration or loss of blood) Aldosterone Adrenal gland Angiotensin II Angiotensinogen Renin production Renin Arteriole constriction Distal tubule JGA

[object Object],[object Object],Figure 44.17

[object Object],Figure 44.18 MAMMALS Bannertail Kangaroo rat ( Dipodomys spectabilis ) Beaver ( Castor canadensis ) FRESHWATER FISHES AND AMPHIBIANS Rainbow trout ( Oncorrhynchus mykiss ) Frog ( Rana temporaria ) BIRDS AND OTHER REPTILES Roadrunner ( Geococcyx californianus ) Desert iguana ( Dipsosaurus dorsalis ) MARINE BONY FISHES Northern bluefin tuna ( Thunnus thynnus )

Chapter 45 Hormones and the Endocrine System

Overlap Between Endocrine and Nervous Regulation ,[object Object],[object Object]

Control Pathways and Feedback Loops ,[object Object],Pathway Example Stimulus Low blood glucose Receptor protein Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Liver Target effectors Response Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target effectors Smooth muscle in breast Response Milk release Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Response Mammary glands Milk production (c) Simple neuroendocrine pathway (b) Simple neurohormone pathway (a) Simple endocrine pathway Hypothalamus Glycogen breakdown, glucose release into blood Figure 45.2a–c

Cell-Surface Receptors for Water-Soluble Hormones ,[object Object],[object Object],Figure 45.3a (a) Receptor in plasma membrane SECRETORY CELL Hormone molecule VIA BLOOD Signal receptor TARGET CELL Signal transduction pathway Cytoplasmic response Nuclear response NUCLEUS DNA OR

[object Object],[object Object],Figure 45.4a–c Different receptors different cell responses Epinephrine  receptor Epinephrine  receptor Epinephrine  receptor Vessel constricts Vessel dilates Glycogen breaks down and glucose is released from cell (a) Intestinal blood vessel (b) Skeletal muscle blood vessel (c) Liver cell Different intracellular proteins different cell responses Glycogen deposits

Intracellular Receptors for Lipid-Soluble Hormones ,[object Object],[object Object]

[object Object],[object Object],(b) Receptor in cell nucleus Figure 45.3b SECRETORY CELL Hormone molecule VIA BLOOD TARGET CELL Signal receptor Signal transduction and response DNA mRNA NUCLEUS Synthesis of specific proteins

Paracrine Signaling by Local Regulators ,[object Object],[object Object]

[object Object],Figure 45.6 Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Ovary (female) Testis (male)

Relation Between the Hypothalamus and Pituitary Gland ,[object Object],[object Object]

[object Object],[object Object],Figure 45.7 Hypothalamus Neurosecretory cells of the hypothalamus Axon Anterior pituitary Posterior pituitary HORMONE ADH Oxytocin TARGET Kidney tubules Mammary glands, uterine muscles

[object Object],[object Object],Tropic Effects Only FSH, follicle-stimulating hormone LH, luteinizing hormone TSH, thyroid-stimulating hormone ACTH, adrenocorticotropic hormone Nontropic Effects Only Prolactin MSH, melanocyte-stimulating hormone Endorphin Nontropic and Tropic Effects Growth hormone Neurosecretory cells of the hypothalamus Portal vessels Endocrine cells of the anterior pituitary Hypothalamic releasing hormones (red dots) HORMONE FSH and LH TSH ACTH Prolactin MSH Endorphin Growth hormone TARGET Testes or ovaries Thyroid Adrenal cortex Mammary glands Melanocytes Pain receptors in the brain Liver Bones Pituitary hormones (blue dots) Figure 45.8

Posterior Pituitary Hormones ,[object Object],[object Object]

Anterior Pituitary Hormones ,[object Object],[object Object]

Tropic Hormones ,[object Object],[object Object],[object Object],[object Object],[object Object]

Nontropic Hormones ,[object Object],[object Object],[object Object],[object Object]

Growth Hormone ,[object Object],[object Object],[object Object]

Thyroid Hormones ,[object Object],[object Object],[object Object]

[object Object],[object Object],Figure 45.9 Hypothalamus Anterior pituitary TSH Thyroid T 3 T 4 +

Parathyroid Hormone and Calcitonin: Control of Blood Calcium ,[object Object],[object Object],Calcitonin Thyroid gland releases calcitonin. Stimulates Ca 2+ deposition in bones Reduces Ca 2+ uptake in kidneys STIMULUS: Rising blood Ca 2+ level Blood Ca 2+ level declines to set point Homeostasis: Blood Ca 2+ level (about 10 mg/100 mL) Blood Ca 2+ level rises to set point STIMULUS: Falling blood Ca 2+ level Stimulates Ca 2+ release from bones Parathyroid gland Increases Ca 2+ uptake in intestines Active vitamin D Stimulates Ca 2+ uptake in kidneys PTH Figure 45.11

Insulin and Glucagon: Control of Blood Glucose ,[object Object],[object Object]

[object Object],Beta cells of pancreas are stimulated to release insulin into the blood. Insulin Liver takes up glucose and stores it as glycogen. Body cells take up more glucose. Blood glucose level declines to set point; stimulus for insulin release diminishes. STIMULUS: Rising blood glucose level (for instance, after eating a carbohydrate- rich meal) Homeostasis: Blood glucose level (about 90 mg/100 mL) Blood glucose level rises to set point; stimulus for glucagon release diminishes. STIMULUS: Dropping blood glucose level (for instance, after skipping a meal) Alpha cells of pancreas are stimulated to release glucagon into the blood. Liver breaks down glycogen and releases glucose into blood. Glucagon Figure 45.12

Target Tissues for Insulin and Glucagon ,[object Object],[object Object],[object Object],[object Object]

Diabetes Mellitus ,[object Object],[object Object],[object Object]

Adrenal Hormones: Response to Stress ,[object Object],[object Object],[object Object]

Catecholamines from the Adrenal Medulla ,[object Object],[object Object]

Stress Hormones from the Adrenal Cortex ,[object Object],[object Object],[object Object]

[object Object],Spinal cord (cross section) Nerve signals Nerve cell Releasing hormone Stress Hypothalamus Anterior pituitary Blood vessel ACTH Adrenal gland Kidney Adrenal medulla secretes epinephrine and norepinephrine. Adrenal cortex secretes mineralocorticoids and glucocorticoids. Effects of epinephrine and norepinephrine: 1. Glycogen broken down to glucose; increased blood glucose 2. Increased blood pressure 3. Increased breathing rate 4. Increased metabolic rate 5. Change in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity Effects of mineralocorticoids: 1. Retention of sodium ions and water by kidneys 2. Increased blood volume and blood pressure Effects of glucocorticoids: 1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose 2. Immune system may be suppressed (b) Long-term stress response (a) Short-term stress response Nerve cell Figure 45.13a,b

Gonadal Sex Hormones ,[object Object],[object Object]

Melatonin and Biorhythms ,[object Object],[object Object]

[object Object],[object Object],Figure 45.15 Brain Neurosecretory cells Corpus cardiacum Corpus allatum EARLY LARVA LATER LARVA PUPA ADULT Prothoracic gland Ecdysone Brain hormone (BH) Juvenile hormone (JH) Low JH Neurosecretory cells in the brain produce brain hormone (BH), which is stored in the corpora cardiaca (singular, corpus cardiacum ) until release. 1 BH signals its main target organ, the prothoracic gland, to produce the hormone ecdysone. 2 Ecdysone secretion from the prothoracic gland is episodic, with each release stimulating a molt. 3 Juvenile hormone (JH), secreted by the corpora allata, determines the result of the molt. At relatively high concen- trations of JH, ecdysone-stimulated molting produces another larval stage. JH suppresses metamorphosis. But when levels of JH fall below a certain concentration, a pupa forms at the next ecdysone-induced molt. The adult insect emerges from the pupa. 4

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