34.2 and 34.3 Respiratory and Excretory Systems Respiratory System Respiratory · sustains cellular respiration (making ATP) by supplying O2 to body cells & Excretory Systems removing CO2 waste from cells Sections 34.2 & 34.3 · 2 processes breathing = moving air into and out of lungs respiration = exchange of gases in the body external = gas exchange between air and blood internal = gas exchange between blood and body cells Path of Air · enters mouth and nose Breathing hairs filter out dust and lg. particles · rate controlled by brain cilia sweep foreign particles responds to levels of CO2 toward throat in bloodstream mucous membranes warm and · inhalation moisten diaphragm contracts, · filtered air enters the pharynx (throat) ribcage expands, and · passes through epiglottis into the air fills lungs larynx (voice box) · exhalation · trachea (windpipe) bronchi lungs diaphragm relaxes, · inside each lung bronchi branch into ribcage contracts, and air flows out of lungs bronchioles · bronchioles lead to alveoli (little air sacs) where external respiration occurs O2 into capillaries CO2 back into lungs for exhale Excretory System Kidneys · aka urinary system · bean-shaped · functions · filter out wastes, water, and remove water (nitrogen-based) and excess water salts from the blood from body · renal cortex - outer layer maintain pH of blood · renal medulla - inner layer · structures · composed of nephrons kidneys, ureters, urinary bladder, urethra 34.2 and 34.3 Respiratory and Excretory Systems Nephrons · filtering unit of the kidney about 1 million in each kidney · blood is filtered in the glomerulus · anything the body needs or can reuse is reabsorbed as it travels through the nephron ex. water, glucose · end product: urine.