Topic 21- Nutrition

What is the process by which food provides energy and nutrients to the body?

Nutrition.

What do herbivores eat?

Only plants (e.g., cows, deer).

What do carnivores require to survive?

Meat (e.g., cats cannot survive on a plant-based diet).

What do omnivores eat?

Both plants and animals (e.g., raccoons, humans); need varied protein sources.

Why do even omnivores need external protein sources?

Because they cannot synthesize all essential amino acids.

How many kcal are in 1g of carbohydrates?

4 kcal.

How many kcal are in 1g of protein?

4 kcal.

How many kcal are in 1g of fat (lipids)?

9 kcal.

What does “1 Calorie” with a capital C equal?

1000 calories (lowercase c).

Which macronutrient has the highest energy yield?

Fats.

What energy source does the brain prefer?

Carbohydrates.

What causes sweat odor after intense workouts?

Protein breakdown produces ammonia.

Where must an animal's carbon source come from?

Organic materials (plants, animals, fungi).

What are essential nutrients?

Nutrients the body cannot synthesize and must ingest.

How many amino acids are essential for adults?

8 (9 for infants).

What are good sources of essential amino acids?

Grains + legumes, spinach, rice, etc.

What are the two essential fatty acids?

Linoleic acid and linolenic acid.

Where can you find essential fatty acids?

Seeds, oils, and vegetables (not much in meat like chicken).

What is the key to a healthy diet?

Variety and moderation.

Why are extreme fad diets problematic?

They may lack essential nutrients.

Are water-soluble vitamins stored in the body?

No, they must be consumed regularly.

What does Vitamin B3 (Niacin) help form?

NAD/NADP (used in respiration).

What condition does B9 (Folic Acid) prevent?

Anemia and neural tube defects.

What is a key dietary concern for vegans related to B12?

B12 is only found in animal products or fortified foods.

What are symptoms of Vitamin C (Ascorbic Acid) deficiency?

Scurvy—bleeding gums, fatigue, tooth loss.

What role does Vitamin A play?

Supports vision (rhodopsin production).

What does Vitamin D help with?

Calcium absorption; deficiency causes rickets or osteomalacia.

Why should Vitamin D supplements be taken cautiously?

Overdosing can cause hallucinations and organ damage.

What are key roles of calcium?

Bone and tooth structure, muscle signaling.

What is phosphorus used for?

ATP, nucleic acids, and phospholipids.

What is sulfur’s role in proteins?

Forms disulfide bridges.

What are trace elements and their roles?

Iron: Hemoglobin and cytochromes (ETC); Iodide: Thyroid hormone synthesis.

What type of feeders are humans?

Bulk feeders.

What stimulates digestive processes?

Presence of food in digestive organs.

What does the satiety center do?

Signals fullness based on stomach stretch.

What hormone increases hunger?

Ghrelin (from the stomach).

What hormones suppress appetite?

Insulin (pancreas), PYY (small intestine), Leptin (fat tissue).

What triggers saliva secretion in the oral cavity?

Neural signals upon food entry.

What hormone does the stomach release when stretched?

Gastrin.

What does gastrin stimulate?

Gastric juice production and churning.

What hormones are triggered by chyme in the small intestine?

CCK: Stimulates pancreas (enzymes) & gallbladder (bile); Secretin: Stimulates pancreas to release bicarbonate.

What effect does high-fat chyme have?

Increases CCK & Secretin → slows stomach emptying.

What happens when blood glucose is high?

Insulin is released.

What happens when blood glucose is low?

Glucagon is released.

What is diabetes mellitus?

A condition caused by insulin deficiency or resistance leading to high blood glucose and complications like blindness and gangrene.

Compare and Contrast the Nutritional Needs of Animals

Category	Herbivores	Carnivores	Omnivores
Diet	Only plants	Only/primarily meat	Plants and animals
Examples	Cows, deer	Cats	Raccoons, humans
Protein Source	Must obtain from plant proteins	Must obtain from animal tissue	Require diverse protein sources
Amino Acids	Must ingest all essential ones	Obtain from meat	Cannot synthesize all; need varied sources
Caloric Needs	Carbs as main source (~50%)	Fat/protein rich	Mixed: carbs, fats, and proteins

Sequence the Regulation of Digestion

1. Food Enters Oral Cavity

   • Neural signals trigger saliva secretion → bolus forms.

2. Swallowing via Pharynx → Stomach

   • Food stretches stomach → gastrin released → gastric juice produced + churning begins.

3. Chyme Enters Duodenum (Small Intestine)

   • CCK triggers enzyme release from pancreas and bile from gallbladder.

   • Secretin stimulates bicarbonate release from pancreas.

4. High Fat Content Detected

   • CCK & Secretin increase → slow stomach emptying and peristalsis.

Hypothesize and Diagnose the Impact of Variability on Digestion Regulation

Variable	Possible Impact
High-fat diet	Increases CCK & secretin → slows stomach emptying → may cause bloating, discomfort
CCK deficiency	Impaired bile/enzyme release → fat malabsorption
Low gastrin production	Reduced gastric juice → impaired protein digestion
Pancreatic enzyme deficiency	Incomplete digestion → nutrient loss

Sequence Calorie Use

• immediate Energy:

  • Carbs are used first (quick energy source, esp. for the brain).

• Short-Term Storage / Moderate Energy:

  • Proteins used if carbs/fats are low (but generate ammonia).

• Long-Term Energy Reserve:

  • Fats (triglycerides) metabolized more slowly but provide more kcal/g.

Hypothesize and Diagnose the Impact of Variability on Calorie Use

Variable	Possible Impact
High-carb intake	Immediate energy available → less fat used
Protein-heavy diet	Risk of ammonia buildup → sweat odor, strain on kidneys
High-fat diet	More stored energy, but slower metabolism → potential weight gain
Starvation or fasting	Body shifts to fat → eventually protein (muscle) for energy

Sequence the Regulation of Appetite and Consumption

• Stomach is Empty

  • Ghrelin released → stimulates hunger.

• Food Intake

  • Insulin (pancreas) and PYY (small intestine) released post-meal → suppress appetite.

• Fat Storage Status

  • Leptin (from adipose tissue) reflects long-term reserves. Low leptin → increased hunger.

• Satiety Center Activation

  • Stomach stretch sends signal to brain → fullness sensed.

Hypothesize and Diagnose the Impact of Variability on Appetite and Consumption

Variable	Possible Impact
Leptin deficiency/resistance	Continuous hunger despite fat stores → risk of obesity
Ghrelin overproduction	Chronic hunger → overeating
Rapid glucose drop post-meal	Appetite returns too soon → may lead to snacking and weight gain
Damaged satiety center	Inability to sense fullness → overconsumption

Sequence Glucose Homeostasis

1. High Blood Glucose (after a meal)

   • Insulin released → glucose uptake by cells → stored as glycogen.

2. Low Blood Glucose (between meals/fasting)

   • Glucagon released → glycogen broken down → glucose released into blood.

Hypothesize and Diagnose the Impact of Variability on Glucose Homeostasis

Variable	Possible Impact
Insulin resistance (Type 2 Diabetes)	Cells fail to absorb glucose → high blood sugar, long-term organ damage
Lack of insulin (Type 1 Diabetes)	Glucose stays in blood → energy-starved cells, high urine output
Excessive insulin release	Hypoglycemia → fatigue, confusion, fainting
Glucagon deficiency	Inability to raise glucose → hypoglycemia risks during fasting