HNF exam 2 preparation

Why is a moderate intake of lipids an essential part of a healthy diet?

They provide long-term energy storage, cushion vital organs, insulate the body against temperature extremes, form cell membranes, and enable the absorption of fat-soluble vitamins

Energy density

Number of calories in a specific weight of food

Nutrient density

The concentration of beneficial nutrients relative to the total calories

Three types of lipids:

Triglycerides, phospholipids, and sterols

Chemical structure of triglycerides:

One glycerol molecule bound to three fatty acid chains

Major body functions of triglycerides:

Primary form of stored energy in adipose tissue; provides insulation and protection

Chemical structure of phospholipids:

One glycerol, two fatty acids, and a phosphate group

Major body functions of phospholipids:

Forms the lipid bilayer of cell membranes; acts as an emulsifier in digestion and transport

Chemical structure of sterols:

Multi-ring carbon structures with no fatty acid tails

Major body functions of sterols:

Serves as a precursor for bile acids, vitamin D, and steroid hormones; structural component of cell membranes

2 essential fatty acids:

Linoleic acid and Alpha-linoleic acid

Linoleic acid

Used to make arachidonic acid and signaling molecules that regulate blood clotting and inflammation

Alpha-linoleic acid

Used to produce EPA and DHA, which are critical for brain development, eye health, reducing inflammation, and maintaining heart health

Digestion process in the mouth and stomach for triglycerides and fatty acids:

Lingual lipase and gastric lipase begins minor breakdown, clearing a small amount of fatty acids

Digestion process in the small intestine for triglycerides and fatty acids:

Presence of fat triggers the release of bile from the gallbladder to emulsify large fat droplets into smaller ones. Pancreatic lipase then breaks triglycerides down into monoglycerides and free fatty acids

Absorption of fatty acids in the small chain:

These chains are water-soluble. They are absorbed directly into the intestinal cells and travel straight into the portal vein to the liver bound to the protein albumin

Absorption of fatty acids in the large chain:

These chains are not water-soluble. They merge with bile to form micelles, which carry them to the edge of the enterocytes. Inside the cell, they are re-assembled back into triglycerides and packaged into chylomicrons before entering the lymphatic system,

Lipoproteins:

Chylomicrons, VLDL, LDL, HDL

Primary component of chylomicrons:

Triglycerides

Core function of chylomicrons:

Transports newly absorbed fats from the intestines to body tissues

Primary component of VLDL:

Triglycerides

Core function of VLDL:

Built by the liver to deliver fats made by the body to cells

Primary component of LDL:

Cholesterol

Core function of LDL:

Delivers cholesterol to tissues

Primary component of HDL:

Protein

Core function of HDL:

Picks up excess cholesterol from cells and returns it to the liver

Physical properties of saturated fatty acids:

Have no double bonds, making their carbon chains straight and tightly packed. They are solid at room temperature.

Physical properties of monounsaturated fatty acids:

Contain one double bond, creating a “kink” or bend in the chain. This prevents tight packing, making them liquid at room temperature.

Physical properties of polyunsaturated fats:

Contains two or more double bonds, making the chains highly bent. They remain liquid at room temperature and cold temperatures.

Physical properties of trans fatty acids:

Unsaturated fats chemically altered to change their double-bond shape from “cis” to “trans”. This straightens the chain, making them behave like saturated fats and turn solid or semi-solid at room temperature.

Common food sources of cholesterol:

Egg yolks, organ meats, shellfish, dairy products, and red meat

Common food sources of saturated fatty acids:

Fatty meats, poultry skin, full-fat dairy, lard, and tropical oils

Common food sources of monounsaturated fatty acids (MUFA’s):

Olive oil, avocados, nuts, canola oil, peanut butter

Common food sources of polyunsaturated fatty acids (PUFA’s):

Vegtable oils, walnuts, seeds, flaxseeds, fish

Common food sources of trans fatty acids:

Partially hydrogenated oils, commercial baked goods, fried foods, vegetable shortening, and ruminant meat

Common food sources of omega-3 fatty acids:

Fatty fish, flaxseeds, walnuts, algae oil, and soybeans

Causes of atherosclerosis:

Artery hardening

Plaque process of atherosclerosis:

Endothelial injury→ LDL oxidation→ white blood cells engulf LDL→ fibrous cap forms

Vascular injuries of atherosclerosis:

Caused by high blood pressure, smoking toxins, and high blood sugar

CVD increase risk factors:

Saturated fat, trans fat, red meat, refined carbs, hypertension, smoking

CVD decrease risk factors:

Unsaturated fats, whole grains, fish oil, fruits, vegetables, healthy weight, physical activity

Alzheimer’s disease risk factors:

Saturated and trans fat increase risk by promoting brain inflammation and amyloid plaques

2015-2020 dietary guidelines:

Saturated fat <10% of daily calories. Trans fat as low as possible.

Sustainable fish nutrients:

Omega-3 fatty acids

Why eat less sustainable fish?

Concerns over mercury contamination and overfishing

Satiety

Sensation of fullness and satisfaction that stops eating behavior

Essential fatty acid

A fatty acid that the body cannot make and must be obtained from food

Triglycerides

The main storage form of fat in the body composed of glycerol and three fatty acids

Fatty acid chain length

The number of carbon atoms in a fatty acid backbone affecting its absorption

Fatty acid saturation

The degree to which carbon bonds are completely filled with hydrogen atoms

Hydrogenation

A chemical process adding hydrogen to unsaturated oils to make them solid

Partial hydrogenation

An incomplete chemical process that creates artificial trans fats

Trans fatty acid

An unsaturated fat with a straight chemical structure that increases heart disease risk

Phospholipid

A structural lipid with a phosphate group that acts as a cell membrane component

Sterol

A class of lipids featuring a multi-ring chemical structure

Cholesterol

A vital sterol used to build cell membranes, bile, and steroid hormones

Pancreas

An organ that secretes lipase enzymes into the small intestine to digest fat

Bile

A liver-produced fluid that prepares dietary fat for digestion

Gallbladder

The organ that stores and concentrates bile until needed for digestion

Emulsification

The breakdown of large fat globules into tiny droplets to aid enzyme action

Lipoprotein

A particle made of lipids and proteins used to transport fat through blood

Micelle

A temporary soluble aggregate of fat digestion products stabilized by bile

Chylomicron

A lipoprotein formed in intestinal cells to transport dietary fat into circulation

VLDL

Very low-density lipoprotein that carries synthesized lipids to body tissues

LDL

Low-density lipoprotein that delivers cholesterol to cells and can cause arterial plaque

HDL

High-density lipoprotein that gathers excess cholesterol and returns it to the liver

Linoleic acid

An essential 18-carbon omega-6 fatty acid

Linolenic acid

An essential 18-carbon omega-3 acid

CVD

Cardiovascular disease affecting the heart and blood vessel network

Atherosclerosis

The narrowing of arteries due to the buildup of fatty plaques

Aneurysm

A dangerous ballooning/widening of a weakened artery wall

Thrombosis

The formation of a blood clot that blocks a blood vessel

Embolism

A floating blood clot or debris that lodges inside a narrow artery

Heart attack

Tissue damage caused by blocked blood flow to the heart muscle

Stroke

Brain tissue damage caused by an interrupted blood supply to the brain

Hypertension

Chronic high blood pressure that strains the circulatory system

How does fat improve satiety?

Satisfaction of being full after a meal

2 essential polyunsaturated fatty acids:

Linoleic acid (Omega-6) and Alpha-linolenic acid (Omega-3)

Lipoprotein

Lipid droplet, with a phospholipid coat, proteins and some cholesterol

Where are chylomicrons formed?

Intestinal absorptive cells

5 types of lipoproteins:

Chylomicrons, VLDL, IDL, LDL, HDL

Possibilities of vascular injuries:

Bacteria/infection, irritants, hyperinsulinemia, increased turbulence of blood flow at branch points

What percentage of American adults have high blood pressure?

46%

Hypertension

When your blood pressure, the force of blood flowing through your blood vessels is consistently too high

Three parts of amino acids:

Amino group, acid group, and side chain

General protein structure:

Large molecules made of chains of smaller building blocks called amino acids linked together by peptide bonds

Only macronutrient that contains nitrogen:

Protein

How many essential amino acids does the body need to get from food?

9

Major roles of protein:

Growth and maintenance, enzymes, hormones, fluid balance, acid-base balance, transportation, antibodies, and energy source

Different paths of amino acids:

• used to build a new protein

• altered to make a non-protein compound

• stripped of nitrogen to be used for immediate energy or stored as fat

Mouth absorption:

Chewing mixes food with saliva, but no chemical protein digestion happens here

Stomach absorption:

Stomach acid denatures proteins and the enzyme pepsin breaks them down into smaller strands

Small intestine absorption:

Pancreatic and intestinal enzymes break strands down into single amino acids, dipeptides, and tripeptides, then absorbs into blood stream

Colon absorption:

Protein is mostly absorbed by this point, only residue moves to colon

Purpose of nitrogen balance studies:

To measure if body is gaining, losing, or maintaining overall protein stores

Method of nitrogen balance studies:

Researchers measure the nitrogen eaten in food versus nitrogen execreted

Positive nitrogen balance:

Intake is greater than output

Negative nitrogen balance:

Output is greater than intake

Mutal supplementation and plant protein:

Combining two incomplete plant protein sources to get all essential amino acids

Risks of high intake of animal protein:

Linked to higher risks of heart disease, kidney stress, and certain cancers