Transcript ppt_ch19e
19 Homeostasis • 19.1 Homeostasis • 19.2 The urinary system • 19.3 The kidney • 19.4 The functions of the kidney • 19.5 Regulation of body temperature • 19.6 The structure and functions of the skin • 19.7 How do mammals control their body temperature? • 19.8 Regulation of glucose level in blood • Mind Map 19.1 Homeostasis 19.1 Homeostasis Rise above normal value e.g. 40oC body temperature Negative feedback Correction mechanism mechanism Normal value e.g. 37oC body temperature Normal value e.g. 37oC body temperature Fall below normal value e.g. 35oC body temperature Correction Negative mechanism feedback mechanism 19.1 Homeostasis 4 by liver & pancreas by skin Blood glucose level 3 Body temperature Constant internal environment by kidneys Salt content 2 by kidneys Water content 1 19.2 The urinary system 19.2 The urinary system Inferior vena cava renal vein right kidney aorta renal artery left kidney ureters sphincter muscle urinary bladder urethra 19.2 The urinary system Kidneys 1 produce urine 1 1 2 2 Ureters 2 carry urine from kidneys to urinary bladder 3 3 Urinary bladder temporary storage of urine 19.2 The urinary system usually tightly contracts so that urine cannot get out sphincter muscle 19.2 The urinary system Urination 1 when it is full urinary bladder 2 relaxes sphincter muscle 3 urethra urine is discharged through urethra 19.2 The urinary system Summary Structure Kidneys Functions Osmoregulation Excretion Ureter Carry urine from kidneys to urinary bladder Urinary bladder Temporary stores urine Urethra Discharges urine 19.2 The urinary system Experiment 19.1 To examine the urinary system of a human torso or a dissected mammal 1. Study a human torso or a dissected mammal (e.g. rat) showing the urinary system. 2. Identify the following parts: kidney, ureter, urinary bladder and urethra. 19.3 The kidney 19.3 The kidney Structure of kidney nephron cortex medulla pelvis 19.3 The kidney Structure of kidney nephron Kidney is made up of about a million nephrons Nephron is the basic unit of kidney 19.3 The kidney first convolution 1+2+3 +4+5 = nephron 2 4 second convolution 1 Bowman’s capsule loop of Henle 3 collecting duct 5 19.3 The kidney 2 glomerulus 4 capillary afferent arteriole 1 efferent arteriole 4 capillary 3 renal venule 5 19.3 The kidney Experiment 19.2 To examine a kidney model or the longitudinal section of a dissected mammalian kidney. 1. Study a kidney model or the longitudinal section of a dissected mammalian kidney. 2. Try to identify the following parts: cortex, medulla, pelvis, ureter, renal artery and renal vein. 19.3 The kidney 19.3 The kidney 1. Ultrafiltration afferent arteriole with larger diameter Increase in hydrostatic pressure in glomerulus efferent arteriole with smaller diameter 19.3 The kidney When the blood passes into glomerulus, due to high hydrostatic pressure all the substances in the blood are forced out through wall of glomerulus into Bowman’s capsular space This liquid is called glomerular filtrate Except: plasma proteins & blood cells 19.3 The kidney is a process that high blood pressure forces small molecules through the walls of glomerulus & Bowman’s capsule into the capsular space 19.3 The kidney 2. Reabsorption Glomerular filtrate passes through the tubule All Amino acids Glucose Some salts are reabsorbed into Most of water blood capillaries around tubule 19.3 The kidney 2. Reabsorption Glomerular filtrate Reabsorption of these useful substances (except water) takes place by diffusion & active transport Water is reabsorbed by osmosis urine contains excess mineral salts water urea 19.3 The kidney is a process that all glucose & amino acids, most of water & some salts are retaken back into capillaries by diffusion, active transport & osmosis 19.4 The functions of the kidney 19.4 The functions of the kidney is the maintenance of the correct level of water in the body Keeps the water level constant 19.4 The functions of the kidney concentrated blood dilute blood 2 after sweating after drinking a lot of water 1 Normal water content in blood a larger proportion of water is reabsorbed a smaller volume of conc. urine is produced 3 after eating a salty meal higher salt conc. in blood extra water is lost with the excretion of excess salts more urine with a high conc. of salt is produced a smaller proportion of water is reabsorbed a larger volume of dilute urine is produced 19.4 The functions of the kidney is a process to remove metabolic wastes 19.4 The functions of the kidney Excretory organs Skin 1 excretes urea and other salts in the sweat Liver excrete bile pigments 3 2 Lungs excrete carbon dioxide Kidneys 4 excrete urea 19.4 The functions of the kidney Excretory organs excess amino acid cannot be stored transport to Liver Deamination 2 nitrogenous waste urea 19.5 Regulation of body temperature Regulation of 19.5 Regulation of body temperature Balance heat gain heat loss maintain a suitable body temperature According to stability of body temperature, two groups of animals Poikilotherms (cold-blooded animals) Homoiotherms (warm-blooded animals) 19.5 Regulation of body temperature Poikilotherms (cold-blooded animals) Little control over their body temperatures invertebrates amphibians Their body temperatures vary with that of the surroundings reptiles fish 19.5 Regulation of body temperature Homoiotherms (warm-blooded animals) Their body temperature can be kept constant irrespective of their environment birds mammals 19.6 The structure and functions of the skin The Structure & Functions of 19.6 The structure and functions of the skin How many layers in the skin? Two layers epidermis dermis 19.6 The structure and functions of the skin How many layers in the epidermis? Three layers Outermost layer Middle layer Epidermis Innermost layer 19.6 The structure and functions of the skin Outermost layer 1 3 reduce water loss dead cells protect the body against mechanical 2 prevent the entry injury of bacteria 19.6 The structure and functions of the skin Middle layer living cells Epidermis Outermost layer Middle layer become dead while approaching the surface 19.6 The structure and functions of the skin Innermost layer 1 produce new cells by mitosis Innermost layers 19.6 The structure and functions of the skin Innermost layer Protect cells from deeper layers UV UV light light 2 Absorb UV light Black pigments Melanin UV light Innermost layers 19.6 The structure and functions of the skin epidermis dermis 19.6 The structure and functions of the skin Heat loss Regulation of body temperature blood vessel Material exchange 2 1 19.6 The structure and functions of the skin sweat pore sweat duct sweat gland secrete sweat cooling excretion 19.6 The structure and functions of the skin hair reduces heat loss and assists in temperature regulation erector muscle contracts to raise hair during cold conditions hair follicle produces hair 19.6 The structure and functions of the skin sebaceous gland secrete sebum keeps the skin waterproof kills microorganisms 19.6 The structure and functions of the skin receptors detect pain touch pressure temperature 19.6 The structure and functions of the skin Experiment 19.3 Examine a skin model or a selection of the mammalian skin 1. Study the model of the mammalian skin. ( OR: Study a preserved slide of mammalian skin. Observe it under the microscope. ) 2. Identify the structure of the mammalian skin. Study how each structure works. 19.6 The structure and functions of the skin Experiment 19.3 Examine a skin model or a selection of the mammalian skin 19.7 How do mammals control their body temperature? How do mammals control their ? 19.7 How do mammals control their body temperature? General idea of thermoregulation Body Body temp. temperature 37oC 37oC Heat Production Heat Loss Environmental temperature 25oC 19.7 How do mammals control their body temperature? Balance Heat Gain Respiration of organism Radiation Convection Conduction from environment Heat Loss Evaporation from organism Radiation Convection Conduction to environment 19.7 How do mammals control their body temperature? What happens when the body is hot? evaporation of sweat heat loss through the skin absorbs heat from skin surface sweat 19.7 How do mammals control their body temperature? What happens when the body is hot? more sweat is produced more heat is absorbed as more sweat evaporates, more heat is lost 19.7 How do mammals control their body temperature? What happens when the body is under hot and humid condition? evaporation of sweat becomes difficult heat loss through the skin by evaporation of sweat becomes ineffective sweat 19.7 How do mammals control their body temperature? Heat production blood skin (body surface) 37oC 25oC (body) Respiration (surrounding) Heat Loss Heat Heat cell by radiation convection, conduction Body temperature can be kept normal 19.7 How do mammals control their body temperature? Vasodilation More Heat Loss Skin temperature more warm blood carried to the superficial blood capillaries skin Skin dilates arteriole artery blood vein 19.7 How do mammals control their body temperature? Hair lie flat erector muscles relax reduces the thickness of air trapped heat loss increases 19.7 How do mammals control their body temperature? Actions for increasing heat loss By Vasodilation Erector muscle relaxes More Sweating brings more blood to the skin more heat loss by • Radiation • Convection • Conduction hairs lie down less heat is trapped heat loss by evaporation of sweat increases 19.7 How do mammals control their body temperature? Actions for decreasing heat loss By Vasodilation brings less blood to the skin reduce heat loss by • Radiation • Convection • Conduction Erector Muscle contracts hairs raise up Less Sweating heat loss by evaporation of sweat decreases more heat is trapped 19.7 How do mammals control their body temperature? What happens when the body is cold? Long-term response A thicker layer of subcutaneous fat & thicker fur are developed Heat loss reduced 19.7 How do mammals control their body temperature? What happens when the body is hot? Long-term response Some mammals develop a thinner layer of subcutaneous fat and shed their fur Heat loss increased 19.8 Regulation of glucose level in blood in 19.8 Regulation of glucose level in blood High blood glucose level stimulates Pancreas secretes more and less insulin glucagon 19.8 Regulation of glucose level in blood High Blood Glucose Insulin promotes How ? this action Glucose Glycogen Liver Normal Blood Glucose 19.8 Regulation of glucose level in blood High blood glucose stimulates secretes more Pancreas insulin and less glucagon Insulin High Blood Glucose Excess glucose Liver Normal Blood Glucose Glycogen Normal Blood Glucose Normal Blood Glucose 19.8 Regulation of glucose level in blood High blood glucose stimulates secretes more Pancreas insulin and less glucagon Insulin High Blood Glucose cannot reabsorb all glucose Excess glucose Liver Normal Blood Glucose Diabetes mellitus urine with glucose Kidneys Glycogen Normal Blood Glucose Normal Blood Glucose 19.8 Regulation of glucose level in blood blood glucose concentration detected by pancreas more insulin and less glucagon is secreted not enough insulin is secreted high blood glucose is kept liver absorbs more glucose in liver converts excess glucose to glycogen lower blood glucose level and higher than the reabsorption capacity in kidney tubules some glucose are excreted in urine Diabetes mellitus Mind Map Homeostasis is the maintenance of includes constant internal environment which is usually controlled by negative feedback mechanism osmoregulation regulation of body temperature regulation of blood glucose level Mind Map osmoregulation controlled by kidneys also for which is made up of excretion urea is removed by nephrons two processes involved urination ultrafiltration reabsorption after sweating larger proportion of water is reabsorbed after drinking a lot of water smaller proportion of water is reabsorbed Mind Map regulation of body temperature controlled by skin hot condition cold condition 1. secret more sweat 1. secret less sweat 2. vasodilation 2. vasoconstriction 3. erector muscles relax 3. erector muscles contract 4. hairs lie flat 4. hairs pulled erect 5. thinner subcutaneous fat 5. thicker subcutaneous fat Mind Map regulation of blood glucose level high blood glucose level low blood glucose level pancreas secretes more insulin but less glucagon pancreas secretes more glucagon but less insulin liver converts glucose to glycogen liver converts glycogen to glucose