NSC-419 Quiz 1 Study Guide

What are the four most abundant elements in the human body?

Oxygen, carbon, hydrogen, and nitrogen.

About how much of body mass is water?

About 55–65%.

What do minerals ("ash") contribute to body mass?

About 5–6% and they support structure and regulation.

What is the main function of the plasma (cell) membrane?

Controls what enters/leaves the cell and maintains a stable internal environment.

What is the plasma membrane made of?

A phospholipid bilayer with embedded proteins; cholesterol helps stabilize fluidity.

Why is cholesterol important in the cell membrane?

It stabilizes the membrane and helps maintain proper fluidity.

What is the nucleus and its main role?

The control center that stores DNA and directs cell activities via gene expression.

Where does transcription occur?

In the nucleus.

Where does translation occur?

At ribosomes in the cytosol or on rough ER.

What is the rough endoplasmic reticulum (RER) and what does it do?

ER with ribosomes; synthesizes proteins for secretion/membranes.

What is the smooth endoplasmic reticulum (SER) and what does it do?

Synthesizes lipids and detoxifies substances (e.g., via cytochrome P450).

What is the Golgi apparatus and what does it do?

Modifies, sorts, and packages proteins/lipids into vesicles for transport/secretion.

What are vesicles used for in cells?

Transport materials within the cell and to the cell membrane for secretion (exocytosis).

What are mitochondria and their main function?

Organelles that produce ATP via aerobic metabolism.

Why do mitochondria have their own DNA?

They evolved from bacteria and can replicate independently.

Where is the electron transport chain (ETC) located?

Inner mitochondrial membrane.

What is the role of the electron transport chain?

Uses electrons from NADH/FADH2 to create a proton gradient that powers ATP synthesis.

Why is oxygen important in the ETC?

Oxygen is the final electron acceptor; without it ATP production drops sharply.

What is ATP?

The cell’s main energy currency used to power cellular work.

Name three types of cellular work that require ATP.

Transport (pumps), chemical work (building molecules), mechanical work (movement/contraction).

What is glycolysis and where does it occur?

Breakdown of glucose in cytosol; net 2 ATP; does not require oxygen.

Where does the Krebs cycle occur and what does it produce?

Mitochondrial matrix; produces NADH and FADH2 for the ETC.

What is fatty acid oxidation (beta-oxidation)?

Breakdown of fatty acids (mainly in mitochondria) to produce acetyl-CoA, NADH, and FADH2 for ATP production.

When does the body rely more on fatty acid oxidation?

During fasting, low-intensity exercise, and when carbohydrate availability is lower.

Why is fatty acid oxidation important?

It provides a major long-term energy source and fuels the Krebs cycle and ETC.

What is mitochondrial biogenesis?

The process of making more mitochondria and improving mitochondrial capacity.

Why would mitochondrial biogenesis increase?

Endurance training, increased energy demand, and cellular signals that promote more ATP capacity.

Name key regulators mentioned for mitochondrial biogenesis.

PGC-1α and mtTFA (TFAM).

What is protein synthesis (overall)?

Making proteins from DNA instructions: transcription (DNA→mRNA) then translation (mRNA→protein).

What does RNA polymerase II do?

Catalyzes transcription (makes mRNA from DNA).

What is the function of mRNA?

Carries the genetic code from nucleus to ribosomes.

What is the function of tRNA?

Brings specific amino acids to the ribosome based on mRNA codons.

What is the function of ribosomes?

Sites of translation where amino acids are assembled into proteins.

How do proteins made on RER typically differ from free-ribosome proteins?

RER proteins are often secreted, membrane-bound, or sent to organelles; free ribosome proteins often stay in cytosol.

What are cellular proteins used for (big categories)?

Structure, signaling, transport, enzymes, and movement.

What is a key role of proteins in cell signaling?

Receptors and signaling proteins detect messages and trigger cellular responses.

What is meant by “chaperoning other compounds”?

Proteins bind/carry other molecules (e.g., transport proteins like albumin).

Why are enzymes important?

They speed up biochemical reactions by lowering activation energy.

What does it mean that enzymes are specific?

Each enzyme typically acts on a specific substrate/reaction.

What is a hormone?

A chemical messenger released into circulation to affect target tissues.

How are hormones generally made (basic categories)?

Peptide/protein hormones, steroid hormones, and amine (tyrosine-derived) hormones.

How are peptide hormones synthesized and released?

Made from amino acids, stored in vesicles, released by exocytosis.

How are steroid hormones synthesized and released?

Made from cholesterol, not stored much, diffuse out when produced.

How do hormones travel in blood?

Peptides circulate freely; steroids often travel bound to carrier proteins.

What is the skeletal system’s main function?

Support, protection, movement leverage, mineral storage, blood cell formation.

What do osteoblasts do?

Build bone by depositing new bone matrix.

What do osteoclasts do?

Break down bone (bone resorption) for remodeling and mineral balance.

What is the nervous system’s main function?

Rapid communication and control using electrical and chemical signals.

What is an action potential?

An electrical signal traveling along a neuron.

What are neurotransmitters?

Chemicals released at synapses to transmit signals between neurons/cells.

Name two neurotransmitters from the notes.

Serotonin and dopamine.

In general, what do serotonin and dopamine influence?

Mood, motivation, reward, and many brain/body functions.

What is the “big picture” objective of the GI system?

Digest food into absorbable nutrients and eliminate waste.

What are the three main objectives of digestion?

Break food down, absorb nutrients/water, and eliminate leftover material.

What is the stomach’s main role in digestion?

Stores and mixes food, begins protein digestion, and controls delivery to the small intestine.

What is gastric juice?

A mixture including HCl, enzymes (like pepsin), mucus, and intrinsic factor.

What does HCl do in the stomach?

Denatures proteins, kills microbes, and activates pepsinogen to pepsin.

Why is intrinsic factor important?

Required for vitamin B12 absorption later in the small intestine.

What is the small intestine’s main role?

The primary site of digestion and nutrient absorption.

How do villi and microvilli help absorption?

They massively increase surface area to maximize nutrient absorption.

What is the brush border?

The microvilli surface with enzymes that finish digestion and aid absorption.

What is the large intestine (colon) mainly responsible for?

Absorbing water/electrolytes, forming stool, and housing gut microbiota.

What are the main GI tract movements?

Peristalsis (propulsion) and mixing/segmentation (mixing with secretions).

What is peristalsis?

Wave-like contractions that move contents forward.

What is segmentation (mixing)?

Back-and-forth movements that mix chyme and enhance digestion/absorption.

What are the 3 phases of digestion?

Cephalic, gastric, and intestinal phases.

What triggers the cephalic phase?

Sight, smell, taste, or thought of food.

What triggers the gastric phase?

Stomach stretching and presence of food.

What triggers the intestinal phase?

Nutrients and acid entering the small intestine.

How are water-soluble nutrients absorbed and transported?

They enter the hepatic portal vein and go to the liver first.

How are fat-soluble nutrients transported?

Packaged into chylomicrons and enter lymph via lacteals.

What is the lymphatic system’s role in digestion?

Transports dietary fats (chylomicrons) and helps with immune defense.

What are probiotics?

Live beneficial microorganisms consumed to support gut health.

What are prebiotics?

Nondigestible fibers/compounds that feed beneficial gut bacteria.

What do gut microbes produce from fiber?

Short-chain fatty acids that support colon health and metabolism.

What are major mediators of hunger?

Ghrelin and neuropeptide Y (NPY).

What are major mediators of satiety?

Leptin, insulin, and CCK.

What does CCK do (high-yield)?

Stimulates pancreatic enzymes and gallbladder contraction; promotes satiety.

What does secretin do (high-yield)?

Stimulates pancreatic bicarbonate to neutralize acidic chyme.

What does gastrin do (high-yield)?

Stimulates gastric acid secretion.

What is bariatric surgery and its purpose?

Surgery to treat severe obesity by restricting intake and/or reducing absorption.

Name common types of bariatric surgery.

Gastric banding, sleeve/gastroplasty, and Roux-en-Y gastric bypass.

Which bariatric surgery can cause malabsorption?

Roux-en-Y gastric bypass (bypasses part of small intestine).

What is GERD?

Acid reflux due to poor closure of the lower esophageal sphincter.

Common symptoms of GERD?

Heartburn, regurgitation, chest discomfort, sour taste.

What is IBS (irritable bowel syndrome)?

A functional GI disorder causing abdominal pain and altered bowel habits without structural disease.

Typical IBS symptoms?

Bloating, cramping, diarrhea and/or constipation.

What is celiac disease?

Autoimmune reaction to gluten causing small intestine damage and malabsorption.

What is Crohn’s disease?

Inflammatory bowel disease that can affect any part of the GI tract (often ileum/colon) with deep inflammation.

Key difference between IBS and IBD (Crohn’s/UC)?

IBS is functional (no tissue damage); IBD involves inflammation and tissue injury.

What is hepatitis?

Inflammation of the liver (often viral, alcohol, or autoimmune causes).

What is fatty liver disease?

Excess fat in liver; can be nonalcoholic (NAFLD) or alcohol-related.

What is cirrhosis?

Long-term liver scarring that impairs liver function.

Why does liver disease matter for nutrition?

The liver processes nutrients; disease can impair metabolism, bile production, and nutrient handling.