Excretion
Excretion
Excretion Excretion = the process by which wastes are eliminated from the body The excretory system includes: Lungs: excrete gaseous carbon dioxide from cellular respiration Rectum: excrete solid undigested remains from food Skin: excretes excess water, salts, urea Kidneys and accessory organs
The Urinary System The urinary system rids the blood of wastes produced by the metabolism of nutrients and controls blood volume by removing excess water produced by body cells. The urinary system includes: Kidneys Urinary bladder Connecting tubules: Ureter Urethra
The Urinary System Section 38-3 Artery Vein Kidney (Cross Section) Cortex Medulla Ureter Urinary bladder Urethra
Kidneys Most people have 2 kidneys located on either side of the spinal column on your lower back Ureters = tubes that carry urine from each kidney to the urinary bladder Urinary bladder = saclike organ that stores urine until it can be excreted The kidneys filter blood by removing urea, excess water and other wastes collected as urine and the clean filtered blood returns to circulation
Kidney Structure Inner part = renal medulla Outer part = renal cortex Functional units of the kidney = nephrons About 1 million nephrons in each kidney Each nephron has its own arteriole (small artery), venule (small vein), and network of capillaries to filter blood
Figure 38–17 Structure of the Kidneys Section 38-3 Kidney Nephron Cortex Medulla Renal artery Renal vein Ureter To the bladder Bowman’s capsule Glomerulus Capillaries Collecting duct To the ureter Loop of Henle Artery Vein FILTRATION…REABSORBTION…SECRETION
Urine The material that remains = urine containing urea, salts, water and other substances The loop of Henle conserves water and minimizes the volume of urine Urine is stored in the urinary bladder until it can be released from the body through a tube = urethra
Kidney Function The kidneys maintain homeostasis by: Regulating the water content of the blood (blood volume) Maintaining blood pH Removing waste products from the blood