Biology Unit 3 Test 2

Digestive and Excretory Systems

Digestion

The process of breaking down food by mechanical and enzymatic action in the alimentary canal into substances that can be used by the body.

Chyme

A thick semifluid mass of partially digested food and digestive secretions that is formed in the stomach and intestine during digestion.

Salvia

We produce about 1.5L a day. It lubricates food and contains salivary amylase for breaking down sugars.

Pancreas

The best known function is for blood glucose regulation but it also produces many digestive enzymes that are released into the small intestine.

Salivary Amylase

A glucose-polymer cleavage enzyme that is produced by the salivary glands.

Gallbladder

Pear-shaped hollow structure that stores bile until it is needed by the small intestine.

Esophagus

Connects the oral cavity to the stomach. Food moves down (or up) by peristalsis (rhythmic muscle contractions). Also secretes mucus for lubrication.

Peristalsis

The rippling motion of muscles in the intestine or other tubular organs characterized by the alternate contraction and relaxation of the muscles that propel the contents onward.

Sphincter

A ring-shaped muscle that relaxes or tightens to open or close a passage or opening in the body.

Liver

Large organ to the right of the stomach below the diaphragm. Main job is to filter blood coming from the digestive tract, and short term sugar storage. It also detoxifies and creates bile for fat digestion.

Alimentary Canal

The organs that food and liquids travel through when they are swallowed, digested, absorbed, and leave the body as feces. These organs include the mouth, pharynx (throat), esophagus, stomach, small intestine, large intestine, rectum, and anus.

Gastric Juice

A unique combination of hydrochloric acid (HCl), lipase, and pepsin. Its main function is to inactivate swallowed microorganisms, thereby inhibiting infectious agents from reaching the intestine.

Kidney

Two fist sized organs in your abdominal cavity close to your spine. Responsible for filtering your blood of unwanted substances and producing urine.

Urinary Bladder

Muscular stretchy container for urine. It can comfortably hold around 500ml but can stretch to hold just over 1000ml. It has a sphincter that we learn to control in childhood.

Glomerulus

Is the site of filtration in the kidney.

Bowman's Capsule

A part of the nephron that forms a cup-like sack surrounding the glomerulus.

Proximal tube

A segment of the renal tubule responsible for the reabsorption and secretion of various solutes and water.

Loop of Henle

Long U-shaped portion of the tubule that conducts urine within each nephron of the kidney. The principal function is in the recovery of water and sodium chloride from urine.

Distal Tube

The region of the nephron that extends downstream from the macula densa to the confluence of another tubule (i.e., the collecting system).

Collecting Duct

The last part of a long, twisting tube that collects urine from the nephrons (cellular structures in the kidney that filter blood and form urine) and moves it into the renal pelvis and ureters.

ADH

A hormone that helps blood vessels constrict and helps the kidneys control the amount of water and salt in the body.

Renal Artery

The main blood vessel that supplies blood to a kidney and its nearby adrenal gland and ureter.

Renal Vein

The main blood vessel that carries blood from the kidney and ureter to the inferior vena cava.

Urethra

The tube to the outside that urine exits through. Approx 20cm in males and 4cm in females.

Ureter

The tube that carries urine from the kidney to the bladder.

Renal Cortex

The outer layer of the kidney. Surrounds the inside of the organ, which is called the medulla.

Renal Medulla

The inner part of the kidney, consists of the medullary collecting ducts, and loops of Henle.

Renal Pelvis

The area at the center of the kidney. Urine collects here and is funneled into the ureter, the tube that connects the kidney to the bladder.

Nephron

The functional unit of the kidney. Approx 1 million per kidney. Non cellular components of blood get squeezed into it and the wanted stuff is reabsorbed.

Reabsorption

The substances from the glomerular filtrate that the body takes in.

Dialysis

A procedure to remove waste products and excess fluid from the blood when the kidneys stop working properly. It often involves diverting blood to a machine to be cleaned.

Peritoneal Dialysis

A type of dialysis which uses the peritoneum in a person's abdomen as the membrane through which fluid and dissolved substances are exchanged with the blood. It is used to remove excess fluid, correct electrolyte problems, and remove toxins in those with kidney failure.

Hemodialysis

Is a process of purifying the blood of a person whose kidneys are not working normally.

Small Intestine

6m long tube where further chemical digestion and finally absorption of nutrients take place. The pancreas and liver add enzymes to break down the food into monomers that can be absorbed by the cells of the lining of the small intestine.

Large Intestine

Major site of water absorption and some vitamins and minerals.

Rectum

The last segment of the large intestine. Holds the feces and has stretch receptors to tell the brain when it is time to go.

Anus

Has muscular sphincters that hold the contents in. When they relax feces is able to leave.