Nutrition Lecture 21

Nutrition

Food used by body for Energy

3 ways in which animals feed

1. Hervibore

2. Carnivore

3. Omnivor

Hervibore

An animal that primarily feeds on plants and plant-based materials for its nutrition.

Carnivore

An animal that primarily feeds on other animals for its nutrition.

Omnivore

An animal that feeds on both plants and other animals for its nutrition.

Opportunistic feeders

Eat whatever is available

Chemical Energy from food used for

Generating ATP through cellular respiration

Measuring Energy

Calorie = a kilocalorie

= energy to raise 1 kg of water by 1°C

Carbohydrates Includes: (2)

1. starch

2. cellulose

Carbohydrates Facts (2) + cal/g?

1. Main Source of energy

2. Its around 50% calories we eat in a day

3. About 1g carb = 4 Calories (4cals/g)

Protein cal/g ?

1g = ~4 Calories

Lipids cal/g ?

1g = ~9 Calories

Most lipids we ingest are:

Triglycerides

Organic Building Blocks (to build/maintain cells)

1. Source of carbon → for building molecules like sugars, fats

2. Protein → Source of nitrogen

Essential Nutrients Facts (2)

• Ingest or die

• They breakdown proteins and lipids

Carbohydrates

NOT essential, the body can make glucose from other molecules, but they are a common source of energy.

Essential Nutrients types (3)

1. Essential Amino Acids

2. Essential Fatty acids

3. Essential Vitamins

Types of Essential Vitamins (2)

1. Water Soluble Vitamins

2. Fat soluble Vitamins

Essential Amino Acids Facts (4)

a. 20 amino acids total

b. Humans can make ~11

i. 8 are essential for adults

ii. 9 for infants (including histidine)

Histidine

Essential Amino Acid only in infants

Essential Fatty Acids (2) where we get from

1. Linoleic acid (omega-6) (polyunsaturated)

2. Linolenic acid (omega-3) (polyunsaturated)

Found in seeds, grains, veggies, and vegetable oils

Essential Vitamins Function

Help enzymes function → many act as coenzymes

Co-enzyme

Non-protein required for enzyme

Water-Soluble Vitamins

Not stored in your body — daily intake needed

Water-Soluble Vitamins Types (2) and subtypes (#1→3)(#2)

B complex vitamins

1. B3 (niacin)

2. B9 (folic acid)

3. B12

Vitamin C (ascorbic acid)

Vitamin B3 (niacin) Role

Part of NAD/NADP (energy metabolism)

Vitamin B9 (folic Acid) Deficiencies (2)

1. Anemia

2. Neural tube defects

Vitamin B12 role(1) + where found (2)

1. Role: Red blood cell formation

2. Where found: yeast/animal products

Vitamin C Roles (3) + 1 deficiency-what it does

1. Collagen

2. Antioxidant - destroys reactive molecules when cells use O2

3. Aids iron absorption

Deficiency: Scurvy = wounds, weakness, loss of teeth

Fat Soluble Vitamins

Are stored in the body

Fat Soluble Vitamins Types (2)

1. Vitamin A

2. Vitamin D

Vitamin A Role

Role: Vision

Is converted to retinal part of rhodopsin

Lack of visual impairment

Deficiency → cant see at night

Rhodopsin

A red-colored pigment found in the rod cells of the retina, responsible for vision in dim light

Vitamin D Role + Deficiency

Calcium absorption (sunlight helps make it)

deficiency → Osteomalacia - bone softening (adults)

Osteomalacia

Bone softening (adults)

Bulk Feeders + example

Organisms that eat large meals occasionally (not constantly), therefore, the digestive system is only active when needed.

ex. humans

Food digestion fact

Each digestive step is triggered as food enters a new compartment of the digestive system.

Nervous System

The Nervous system and hormones coordinate when to digest and when to stop eating.

Food arrival → secretion of hormones for chemical digestion & peristalsis(muscle contractions for digestion)

Satiety Center

Center in the brain that receives signals to regulate hunger and fullness.

Hormone that stimulate appetite (1)

Ghrelin

Hormones suppress appetite (3)

1. Insulin

2. PYY

3. Leptin

Insulin (source + trigger + function)

Pancreas + After a meal + Suppresses appetite

PYY (source + trigger + function)

Small intestine → After food enters → Suppresses appetite

Leptin (source + trigger + function)

Fat (adipose tissue) → Fat storage levels → Suppresses appetite long-term

Ghrelin (source + trigger + function)

Stomach wall → Empty stomach → Stimulates hunger (tells you to eat)

Regulation of digestion (oral cavity) (4 steps)

Food → Oral cavity → nervous system → saliva

Swallowing

Happens when bolus reaches pharynx

Regulation of digestion (Stomach) (5 steps)

Food → stretches the stomach → activates enteric division of nervous system → gastrin triggered

Gastrin Stimulates (2)

1. Gastric juice (HCl + pepsin)

2. Stomach churning

(is released after stomach is stretched)

Regulation of digestion (Small Intestine) (3 steps)

Chyme → Si (duodenum) → Presence of amino acids & fatty acids triggers two hormones (CKK and Secretin)

Cholecystokinin (CKK) hormone (targets (2) + functions)

Target: Pancreas, Gallbladder

Function:

1. Pancreas → release digestive enzymes

2. Gallbladder → release bile

Secretin Hormone (target(1) + function)

Target: Pancreas

Function: Stimulates bicarbonate (HCO₃-) to neutralize acid

High Fat Meal? = Chyme is high in fats (2 results)

• CCK and secretin will be very high

• Inhibits ↓ peristalsis & ↓ gastric juices → slows digestion for better fat breakdown

High glucose / Blood sugar rises?

Insulin secreted (stores glucose in body cells for later use)

Low glucose / Blood sugar drops?

Glucagon secreted (breaks down stored glycogen for NOW use)

Diabetes Mellitus

When Glucose Regulation Fails - Not enough insulin OR target tissues don’t respond to it.

What happens when Insulin deficiency/or doesn’t reach target area

Kidneys excrete glucose(throw it out)

Consequences of Kidney Excreting glucose (3)

1. Eyes (blindness)

2. Limbs (gangrene - limb rotting)

3. Kidneys (failure)