Lecture 8 - Nutrition

What are essential nutrients?

Required materials that an animal needs but cannot assemble from simple organic molecules. They include essential amino acids, essential fatty acids, vitamins, and minerals.

How many amino acids do all organisms require, and how many can animals synthesize?

All organisms require 20 amino acids. Animals can synthesize about half, and the rest (essential amino acids) must be obtained from food.

What are essential fatty acids, and where do animals typically get them?

Essential fatty acids are certain unsaturated fatty acids that animals must obtain from their diet. They are found in seeds, grains, and vegetables.

What are vitamins, and how are they categorized?

Vitamins are organic molecules required in small amounts. They are categorized into fat-soluble and water-soluble vitamins.

Why should polar bear livers not be eaten?

They contain extremely high levels of vitamin A, which can cause hypervitaminosis A, leading to symptoms like skin peeling, vomiting, vision damage, and even death.

What are minerals, and what happens if ingested in large amounts?

Minerals are simple inorganic nutrients required in small amounts. Ingesting large amounts can upset homeostatic balance.

What are the three main dietary categories for animals?

Herbivores (plants/algae), carnivores (other animals), and omnivores (both plants and animals.)

What is malnutrition, and how does it affect young animals?

Malnutrition is a failure to obtain adequate nutrition, which can cause deformities, disease, and death, especially in young animals.

What is undernourishment, and what are its effects?

Undernourishment occurs when a diet lacks sufficient chemical energy. It leads to the breakdown of stored fat, carbohydrates, and proteins, causing muscle loss, brain protein deficiency, and potentially irreversible damage or death.

What is ingestion, and what are the four feeding mechanisms in animals?

Ingestion is the act of eating or feeding. The four feeding mechanisms are filter feeders, substrate feeders, fluid feeders, and bulk feeders.

What is digestion, and what are its two main types?

Digestion is the process of breaking food into absorbable molecules. The two types are mechanical digestion (chewing/grinding) and chemical digestion (enzymatic hydrolysis).

Where does most nutrient absorption occur in humans?

Most nutrient absorption occurs in the small intestine (95% of nutrient molecules, excluding water).

What is elimination, and how does it occur in humans?

Elimination is the passage of undigested material out of the digestive system. Feces are processed in the large intestine and eliminated through the anus, while liquid waste is filtered by the kidneys and excreted as urine.

What is extracellular digestion, and how does it differ from intracellular digestion?

Extracellular digestion occurs outside cells in specialized compartments, while intracellular digestion occurs inside cells via food vacuoles and lysosomes.

What is the role of the stomach in digestion?

The stomach stores food, secretes gastric juice (HCl and pepsin), and churns food into a liquid suspension called chyme.

What is the function of bile in digestion?

Bile, produced by the liver and stored in the gallbladder, contains bile salts that facilitate fat digestion and destroy nonfunctional red blood cells.

How does the small intestine maximize nutrient absorption?

The small intestine has villi and microvilli that create a brush border, greatly increasing the surface area for nutrient absorption.

What is the role of the liver in nutrient processing?

The liver regulates nutrient distribution, interconverts organic molecules, and detoxifies harmful substances.

What is dentition, and how does it reflect an animal’s diet?

Dentition refers to an animal’s assortment of teeth, which is specialized for different diets (e.g., carnivores have sharp teeth for tearing meat, while herbivores have flat teeth for grinding plants).

What is the microbiome, and what role does it play in digestion?

The microbiome is the collection of microorganisms living in and on the body. Some intestinal bacteria produce vitamins, aid digestion, and support immune function.

How do ruminants digest cellulose?

Ruminants have specialized fermentation chambers where mutualistic microorganisms break down cellulose.

What regulates digestion in the body?

Digestion is regulated by the enteric nervous system and hormones from the endocrine system.

How is energy stored in the human body?

Energy is stored as glycogen in the liver and muscles, and excess energy is stored as fat in adipose cells.

What is glucose homeostasis, and which hormones regulate it?

Glucose homeostasis is the balance of blood sugar levels, regulated by insulin (lowers blood sugar) and glucagon (raises blood sugar).

What are the two types of diabetes mellitus?

Type 1 diabetes is an autoimmune disorder where the immune system destroys pancreatic beta cells. Type 2 diabetes involves impaired regulation and uptake of glucose by cells.

Which hormones regulate appetite?

Ghrelin (triggers hunger), insulin and PYY (suppress appetite after meals), and leptin (regulates body fat levels and suppresses appetite).