The Human Body: A Comprehensive Study Guide

General Outcomes

• Explain how the human digestive and respiratory systems exchange energy and matter with the environment.
• Explain the role of the circulatory and defense systems in maintaining homeostasis.
• Explain the role of the excretory system in maintaining homeostasis through the exchange of energy and matter with the environment.
• Explain the role of the motor (muscular) system in the function of other body systems.

Unit Contents

• Chapter 6: Digestion and Human Health
• Chapter 7: The Respiratory System
• Chapter 8: Circulation and Immunity
• Chapter 9: Excretion and the Interaction of Systems
• Chapter 10: The Muscular System and Homeostasis

Focussing Questions

• What factors influence the healthy functioning of the body?
• How can technology assist the healthy functioning of the body?

Sarah Reinertsen

• Athlete who competes in running events and triathlons despite using a prosthetic leg.
• Requires 40% more oxygen and twice as much energy compared to an athlete with two legs for the same feats.
• Organ systems are finely tuned through training.

Human Systems

• Vital function: providing and using matter and energy for life-sustaining activities.
• The body obtains necessary materials, rids itself of waste, and transforms matter into energy.
• Processes are unified and regulated in a way that medical technologies cannot replicate.

Unit 4 Preparation: Prerequisite Concepts

• Builds on knowledge of animal cell structure and function, cell membrane, and cellular respiration.

Organ Systems of the Human Body

• Integumentary system:
  • Protects body from infection
  • Receives sensory input
  • Helps control body temperature
  • Synthesizes vitamin D
• Skeletal system:
  • Provides framework for muscles
  • Produces blood cells
  • Stores minerals
  • Protects soft organs
• Nervous system:
  • Detects, interprets, and responds to stimuli
  • Coordinates organ-system functions with the endocrine system
• Endocrine system:
  • Produces hormones
  • Helps coordinate organ systems
  • Responds to stress
  • Regulates fluid and pH balance
  • Regulates metabolism
• Respiratory system:
  • Delivers oxygen to blood
  • Removes carbon dioxide from cells
  • Helps control blood pH
• Circulatory system:
  • Transports blood, nutrients, gases, and metabolic wastes
  • Defends body against disease
  • Helps control temperature, fluid balance, and pH balance
• Lymphatic and immune systems:
  • Help control fluid balance
  • Defend against disease
  • Absorb fats (lymphatic)
• Excretory system:
  • Removes metabolic wastes
  • Helps control fluid balance
  • Helps control pH balance
• Muscular system:
  • Maintains posture
  • Moves body and organs
  • Produces heat
• Digestive system:
  • Breaks down food into chemical components for circulation
  • Eliminates undigested food
• Reproductive system:
  • Produces gametes (sperm or ova)
  • Transports gametes
  • Produces sex hormones
  • Nourishes offspring (in females)

Human Systems

• Cells of the same type interact to form specialized tissues.
• Tissues interact to form organs.
• Several organs linked physically or functionally form organ systems.

Focus of the Unit

• The first six organ systems are shown and summarized (Integumentary, Skeletal, Nervous, Endocrine, Respiratory, and Circulatory).
• Other organ systems will be studied in the next biology course.

Homeostasis and Negative Feedback

• Homeostasis: The tendency of the body to maintain a relatively constant internal environment.
  • Body temperature near 37 °C.
  • Blood pH near 7.4.
  • Blood glucose level around 100 mg/mL.
• Mechanism:
  • Sensor: Detects change in the internal environment.
  • Effector: Brings internal conditions back to normal range.
  • Control center: Activates the effector based on information from the sensor.
• Negative Feedback: The main homeostatic mechanism.
  • Sensor detects a change.
  • Control center activates an effector.
  • Effector reverses the change and restores balance.

Chapter 6 Concepts

• 6.1 The Molecules of Living Systems
  • Macromolecules (carbohydrates, lipids, proteins, nucleic acids) are made of smaller subunits separated through hydrolysis.
  • Enzymes are biological catalysts.
• 6.2 The Human Digestive System
  • The digestive tract is a tube from the mouth to the anus where food is broken down, nutrients are absorbed, and undigested material is eliminated.
  • Food is processed mechanically and chemically to reduce macromolecules for absorption into the bloodstream.
• 6.3 Health and the Digestive System
  • Excess or deficiency of nutrients can lead to disorders that can be diagnosed and treated but not necessarily cured.

Visualizing the Human Body Technologies

• Thermograms: Map heat given off by the body; colors indicate temperature ranges.
• Capsule endoscopy: Internal-camera technology to view the digestive system from the inside.
• X-ray machine: Imaging technology to peer inside the body.

6.1 The Molecules of Living Systems

• Section Outcomes:
  • Describe the chemical nature of carbohydrates, lipids, and proteins.
  • Explain how carbohydrates, lipids, and proteins are synthesized and broken down (hydrolyzed).
  • Perform standard tests to identify macromolecules.
• Key Terms: Macromolecules, dehydration synthesis, hydrolysis, carbohydrates, lipids, proteins, peptide bond, nucleic acids, vitamins, minerals, catalyst, enzyme
• Body Fluids: Cytoplasm, fluid between cells, fluid in blood.
  • Mostly water (over 60% of body).
  • Contain molecules and ions (water, phosphates, hydrogen ions, sodium ions).
  • Inorganic (non-living) matter.
• Organic Molecules: Contain carbon bonded to hydrogen, as well as other atoms (oxygen, sulfur, and nitrogen).
• Macromolecules: Larger, more complex assemblies of organic molecules.
  • Four major categories: carbohydrates, lipids (fats), proteins, and nucleic acids.
  • Polymers: Long molecules formed by linking small, similar chemical subunits.
    *Macrosaccharides examples are sugars, starches, and glycogen.
    *Lipids examples are Fats, oils, and phospholipids.
    *Proteins examples are hemoglobin, fibrin, collagen, antibodies, enzymes, actin, and Myosin.
    *Nucleic acid examples are DNA and RNA.

Assembling Macromolecules

• Covalent bond forms between two subunit molecules.
• -OH (hydroxyl) group removed from one subunit, hydrogen atom removed from the other.
• Dehydration synthesis: Removing -OH group and H atom removes a molecule of water (H2O). Requires enzymes.
• Enzymes: Special class of proteins that position and break chemical bonds.

Disassembling Molecules

• Cells disassemble macromolecules into component subunits.
• Hydrolysis: Molecule of water is added instead of removed.
• Hydrogen atom from water attaches to one subunit, hydroxyl group bonds to another effectively breaking a covalent bond in a macromolecule; requires enzymes.

Carbohydrates

• Contain carbon, hydrogen, and oxygen (usually in the proportion of two hydrogen atoms and one oxygen atom for every carbon atom).
• Provide short-term or long-term energy storage.
• Two main types: simple sugars and polysaccharides.

Simple Sugars

• Monosaccharide: Carbohydrate molecule with three to seven carbon atoms (and the corresponding number of hydrogen and oxygen atoms).
• Disaccharide: Double sugar made up of two simple sugars.

Polysaccharides

• Complex carbohydrate consisting of many linked simple sugars.
• Starch: Energy storage in plants.
• Glycogen: Energy storage in animals (more branching than starch).
• Cellulose: Polysaccharide in plants

Lipids

• Diverse group of macromolecules insoluble in water.
• Store 2.25 times more energy per gram than other biological molecules.
• Energy-storage molecules.
• Phospholipids: Form a membrane separating a cell from its external environment.
• Steroids: Sex hormones (estrogen and testosterone).
• Fats and oils:
  • Fats (butter, lard): Usually animal origin; solid at room temperature.
  • Oils (olive oil, safflower oil): Plant origin; liquid at room temperature.
• Form when one glycerol molecule reacts with three fatty acid molecules.
• Sometimes called a triglyceride.
• Neutral fat: Non-polar.
• Fatty acids may be identical or different, short or long, saturated or unsaturated.
• Saturated fatty acid: No double covalent bonds between carbon atoms; contains all the hydrogen atoms it can bond with.
• Unsaturated fatty acid: Double bonds between some carbon atoms, leaving room for additional hydrogen atoms; causes the resulting fat to be liquid at room temperature.

Proteins

• Most cellular structures are made of different types of proteins.
• Serve many functions in cells and display greater structural complexity and functional diversity than either lipids or carbohydrates.
• Hair and fingernails are made of keratin.
• Bones, muscles, ligaments, and tendons contain very different proteins.
• Subunits are amino acids.
• Amino acids: Central carbon atom bonded to a hydrogen atom and three other groups of atoms—amino group, acid group, and R group.
• R group: Determines identity and distinguishes the 20 types of amino acids.
• Body can synthesize 11 amino acids; the other nine are essential amino acids (from diet).
• Amino acids bond together in strands to form proteins.
• Connected by a type of bond called a peptide bond.
• A chain of several amino acids bonded together is called a peptide.
• If amino acids are bonded, the chain is called a polypeptide.
• Strand of amino acids undergoes additional changes to become a protein; attract and repel each other, causing the strand to coil and twist into a three-dimensional structure.
• Final shape determines its properties and functions.
  *Electrically charged groups are attracted to water.
  *Proteins with these R groups, such as enzymes and hemoglobin, are soluble water.
  *Other R groups are not electrically charged and are repelled by water.
  *Proteins with these R groups, such as the keratin in your fingernails, are not soluble water.

Nucleic Acids

• Direct the growth and development of all organisms using a chemical code.
• Determine how a cell functions and what characteristics it has.
• Two types: RNA (ribonucleic acid) and DNA (deoxyribonucleic acid).
• DNA contains genes to build the cell.
• A gene is first copied into RNA, which then is involved in making a protein.
• Consist of long chains of linked subunits called nucleotides.
• DNA and RNA are made up of just four different nucleotides.

Vitamins and Minerals

• Not macromolecules, but essential to the structure and function of all cells.
• Key components of chemical reactions that yield energy, synthesize compounds, and break down compounds.
• Vitamins: Organic compounds; only small amounts required by the body; serve as coenzymes, are involved in tissue development, tissue growth and resistance to disease.
• Minerals: Inorganic compounds; only small amounts required by the body; enable chemical reactions to occur and help to build bones and cartilage; readily absorbed into the bloodstream; essential components of molecules such as hemoglobin, hormones, enzymes, and vitamins.

Enzymes

• A catalyst is a chemical that speeds up a chemical reaction but is not used up in the reaction. It can be recovered unchanged when the reaction is complete.
• Protein molecule that acts as a catalyst to increase the rate of a reaction.
• In red blood cells, carbonic anhydrase enables carbon dioxide and water to react and form about 600 000 molecules of carbonic acid each second.

How Enzymes Speed Chemical Reaction Rates

• Enzyme has a precise three-dimensional shape specific to the kind of reactant molecule it can combine with.
• Enzyme physically fits with a specific substrate (reactant molecule).
• Part of the enzyme that binds to the substrate is called the active site.
• When the substrate binds to the active site, its bonds become less stable and, thus, more likely to be altered and to form new bonds.

Factors Affecting Enzyme Action

• Temperature and pH can affect the action of enzymes.
• Enzyme activity is affected by any change in condition that alters the enzyme’s three-dimensional shape.
• When the temperature becomes too low, the bonds that determine enzyme shape are not flexible enough to enable substrate molecules to fit properly.
• At higher temperatures, the bonds are too weak to maintain the enzyme’s shape.
• It becomes denatured, meaning that its molecular shape and structure (and, thus, its properties) are changed.
• Enzymes function best within an optimal temperature range.
• Enzymes also function within an optimal pH range; most human enzymes work best within pH 6 to 8.
• Competitive inhibitor: attaches to the enzyme in the enzyme's active site.
• Non-competitive inhibitors: a regulatory molecule that binds to an enzyme somewhere other than the active site, causing the active site to change shape thereby effectively deactivating the enzyme by stopping its ability to bind to the substrate site.

6.2 The Digestive System

• Section Outcomes:
  • Identify the main structures and functions of the digestive system.
  • Describe the physical and chemical processing of food through the digestive system and into the bloodstream.
  • Explain the action of enzymes in chemical digestion.
  • Identify and describe how digested molecules enter the bloodstream.
• Key terms: digestive system, mouth, amylase, esophagus, peristalsis, esophageal sphincter, stomach, pyloric sphincter, pepsin, small intestine, segmentation, duodenum, villi, microvilli, pancreas, liver, gall bladder, carbohydrases, lipases, proteases, nucleases, gastrin, secretin, CCK, GIP, large intestine

The Digestive System

• Specialized to ingest food, move it through a tube (digestive tract), and break it down into smaller components (digest it).
• Digestion: Physical breakdown, through motions such as chewing, churning and segmenting, and chemical breakdown, through hydrolysis.
• Resulting substances are absorbed into the bloodstream and delivered to body cells.
• Solid wastes are eliminated via the anus.

The Diagram of the Digestive System

• The Digestive Tract (Organs That Contain Food): mouth, esophagus, stomach, small intestine, large intestine, rectum, anus.
  Accessory Organs- salivary glands, liver, gull bladder and pancreas.
  *Mouth- Chews and mixes food with saliva.
  *Esophagus- directs food from mouth to stomach.
  *Stomach- Adds acid, enzymes, and fluid; churns, mixes, and grinds food to a liquid mass.
  *Small Intestine- Secretes enzymes that digest macromolecules; absorbs hydrolyzed molecules into bloodstream.
  *Large Intestine- Absorbs water and salts; passes remaining undigested material and some water out of the body).
  *Rectum- Stores waste prior to elimination.
  *Anus- Holds rectum closed; opens to allow elimination.
  *Liver- Manufactures bile, a detergent like substance that facilitates digestion of fats.
  *Gall Bladder- Stores bile until needed.
  *Pancreas- Manufactures enzymes to digest macromolecules; secretes bicarbonate to neutralize stomach acid that enters small intestine.
• Digestive tract also referred to as gastrointestinal or GI tract or alimentary canal.
• Term alimentary comes from a Latin word that means “nourishment.”

Digestion Begins: The Mouth and the Esophagus

• Saliva secreted by salivary glands: contains Saliva is one of many fluids and substances that are secreted by the digestive tract to aid digestion.
• Enzyme in saliva (salivary amylase) begins to break down starch into simpler sugars (disaccharides) = chemical digestion (hydrolysis).
  *Function of saliva:
  *Contributes to starch digestion via salivary amylase.
  *Lubricates the inside of the mouth to assist in swallowing.
  *Function of Mucus in the digestive tract: Mouth, stomach, small intestine, and large intestine- Protects the cells lining the innermost portion of the digestive tract; lubricates food as it travels through the digestive tract.
  *Function of Enzymes in the digestive tract: Mouth, stomach, small intestine, and pancreas- promote digestion of food masses into particles small enough for absorption into the bloodstream.
  *Function of Stomach Acids in the digestive tract: Stomach: Promotes digestion of protein.
  *Function of Bile in the digestive tract: _Liver (stored in gull bladder)- Suspend fat in water, using bile salts, cholesterol, and lecithin to aid digestion of fats in small intestine.
  *Function of hormones in the digestive tract*Stomach, Small Intestine, and Pancreas- Stimulate production and/or release of acid, enzymes, bile, and bicarbonate; help to regulate peristalsis.
• Physical digestion begins as teeth chew food into smaller pieces.
• Water and mucus in saliva aid the teeth as they tear and grind food into smaller pieces, increasing the surface area available for the chemical digestion of any starch that has been ingested.
• Tongue rolls the food into a bolus and pushes it to the back of the mouth for swallowing.
• Bolus enters the esophagus, passing the covered opening of the trachea.
• Movement closes the trachea against the epiglottis and prevents food from entering the lungs.
• Esophagus: Muscular portion of the digestive tract that directs food from the mouth to the stomach.
• Bolus moves through the esophagus partly by gravity, but mainly through peristalsis (muscular contractions and relaxations).
• Controlled by the esophageal sphincter, which relaxes to allow the bolus into the stomach and contracts to prevent acidic stomach contents from backing up into the esophagus (heartburn).
• Peristalsis moves food through the esophagus.
• Peristalsis Involves two layers of the muscles that line the digestive tract. One layer of longitudinal muscles run parallel to the length of the tract. Beneath these muscles, and perpendicular to them, is a circular layer of muscles. To move food, the circular muscles over a bolus relax, while the longitudinal muscles in front of the bolus contract. The circular muscles behind the bolus then contract, while the longitudinal muscles over it relax. Repetition of these movements pushes the bolus along.

Storing, Digesting, and Pushing Food: The Stomach

• J-shaped, muscular, sac-like organ.
• Three important functions: storage, some digestion, and pushing food into the small intestine.
• Empty stomach is the size of a large sausage (50 mL capacity), but can expand to hold 2 L to 4 L of food!
• Folds in the stomach’s lining (rugae) unfurl to accommodate a large meal.
• Pyloric sphincter controls the exit of the stomach’s contents into the small intestine.
• Physical and chemical digestion occur in the stomach.
• Waves of peristalsis push food against the bottom of the stomach, churning it backward, breaking it into smaller pieces, and mixing it with gastric juice to produce a thick liquid called chyme.
• About 40 million cells lining the interior of the stomach secrete 2 L to 3 L of gastric juice each day.
  Gastric juice: responsible for chemical digestion in the stomach.
• Made up of water, mucus, salts, hydrochloric acid, and enzymes.
• Hydrochloric acid (pH 1 to 3) provides a highly acidic environment that begins to soften and break down proteins in the chyme; also kills most bacteria.
• The stomach produces its protein-digesting enzyme, pepsin, in a form that remains inactive until hydrochloric acid is present.
• Once active, pepsin hydrolyzes proteins to yield polypeptides

Absorption in the Stomach

• Very few substances are absorbed because most substances in the chyme have not yet been broken down sufficiently.
• The stomach does absorb some water and salts, as well as certain anti-inflammatory medications and alcohol.

Digesting and Absorbing Nutrients: The Small Intestine

• Small intestine :The longest part of the digestive tract with more than four times the length of the large intestine.
• Small only in terms of its diameter (compared with the large intestine).
• Physical digestion occurs through segmentation: Chyme sloshes back and forth between segments of the small intestine that form when bands of circular muscle briefly contract.
  Meanwhile, peristalsis pushes the food along the intestine.
• Main function: Complete the digestion of macromolecules and to absorb their component subunits.

Regions and Structures of the Small Intestine

• The first 25 cm of the small intestine is called the duodenum.
• Duodenum is generally U-shaped and is the -shortest and widest of three regions located within the small intestine. Ducts (channels) from the liver and pancreas join to form one duct that enters the duodenum.
• Innermost surface is corrugated with circular ridges (about 1.3 cm high).
• Surface of every