Unit 3 - Digestion & Excretion

Question 1

What organs make up the gastrointestinal tract?

Answer 1

Mouth, esophagus, stomach, small intestine, large intestine, rectum, anus

Question 2

What are the accessory organs of digestion?

Answer 2

Liver, pancreas, gall bladder

Question 3

Describe peristalsis and its role in digestion.

Answer 3

Peristalsis is an involuntary muscle contraction that moves rapidly along an organ like a wave and pushes food through the GI tract

Question 4

Define mechanical and chemical digestion.

Answer 4

Mechanical digestion is the physical breakdown of chunks of food into smaller pieces.

Chemical digestion is the chemical breakdown of large, complex food molecules into smaller, simpler nutrient molecules that can be absorbed by the blood.

Question 5

What is amylase and what is its role?

Answer 5

major salivary enzyme is amylase. It begins the chemical digestion of carbohydrates by breaking down starch into sugar.

Question 6

Describe functions of the stomach.

Answer 6

Churning movements of the stomach’s thick, muscular walls complete the mechanical breakdown of food. & also mix food with digestive fluids secreted by the stomach

produces hydrochloric acid which
It kills bacteria in food

Question 7

What is pepsin?

Answer 7

Digestive enzyme which chemically digests protein.

Question 8

Describe the functions of the three parts of the small intestine.

Answer 8

the duodenum– most chemical digestion
Jejunum– most nutrient absorption
Ileum– remaining absorption

Question 9

What role do villi play in absorption?

Answer 9

they greatly increase the surface area for absorption.

Question 10

Describe the functions of the three parts of the large intestine.

Answer 10

Cecum - where wastes enter
Colon - water is absorbed
Rectum - feces is accumulated

Question 11

How do bacteria in the large intestine help keep us healthy?

Answer 11

produce vitamins, which are absorbed by the large intestine. Other functions of intestinal bacteria include:
controlling the growth of harmful bacteria.
breaking down indigestible food components.
producing substances that help prevent colon cancer.
breaking down toxins before they can poison the body

Question 12

Compare and contrast macronutrients and micronutrients. Give examples of each.

Answer 12

Nutrients are substances the body needs for energy, building materials, and control of body processes.

Nutrients the body needs in relatively large amounts are called macronutrients. Carbs, proteins, fats

Nutrients the body needs in relatively small amounts are called micronutrients. Vitamins and minerals

Question 13

What are minerals? Give two examples.

Answer 13

Minerals are chemical elements that are essential for body processes. They include calcium, which helps form strong bones and teeth, and potassium, which is needed for normal nerve and muscle function.

Question 14

What is excretion?

Answer 14

Excretion is the process of removing wastes and excess water from the body. It is one of the major ways the body maintains homeostasis.

Question 15

List organs of the excretory system and their functions.

Answer 15

Kidneys - produce urine
The large intestine eliminates solid wastes that remain after the digestion of food.
The liver breaks down excess amino acids and toxins in the blood.
The skin eliminates excess water and salts in sweat.
The lungs exhale water vapor and carbon dioxide

Question 16

Describe how nephrons filter blood and form urine.

Answer 16

-Blood enters the kidney through the renal artery, which branches into capillaries. When blood passes through capillaries of the glomerulus of a nephron, blood pressure forces some of the water and dissolved substances in the blood to cross the capillary walls into Bowman’s capsule.

• The filtered substances pass to the renal tubule (PCT, loop of Henle, DCT) of the nephron. In the renal tubule, some of the filtered substances are reabsorbed and returned to the bloodstream. Other substances are secreted into the fluid.
• The fluid passes to a collecting duct, which reabsorbs some of the water and returns it to the bloodstream. The fluid that remains in the collecting duct is urine

Question 17

State the functions of the ureters, bladder, and urethra.

Answer 17

urine enters the ureters, two muscular tubes that move the urine by peristalsis to the bladder The bladder is a hollow, sac-like organ that stores urine. The urethra is a muscular tube that carries urine out of the body. Urine leaves the body through another sphincter in the process of urination.

Question 18

What is the nephron? How many nephrons are in each kidney?

Answer 18

Nephrons are the structural and functional units of the kidneys. A single kidney may have more than a million nephron

Question 19

Explain how the kidneys maintain homeostasis.

Answer 19

Filter the blood to remove waste
ADH regulates water reabsorption in the kidneys
Renin & aldosterone help to regulate blood pressure