Chapter 24

Question 1

Carbohydrate uses in the body

Answer 1

Glucose - fuel used by cells to make ATP
Neurons and RBCs - entirely on glucose
Excess converted to glycogen or fat
Fructose and galactose converted to glucose by liver before circulation

Question 2

Lipids

Answer 2

Triglycerides (neutral fats)
Saturated fats in meat, dairy foods, and tropical oils; trans fats
Unsaturated fats in seeds, nuts, olive oil, and most vegetable oils
Cholesterol in egg yolk, meats, organ meats, shellfish, milk
Liver makes ~85% cholesterol

Question 3

Uses of Lipids in the Body

Answer 3

Help absorb fat-soluble vitamins
Fuel of hepatocytes, skeletal muscle
Myelin sheaths, membranes
Protection, insulation, fuel storage
Prostaglandins – smooth muscle contraction, BP control, inflammation
Cholesterol stabilizes membranes; precursor of bile salts, steroid hormones

Question 4

What’s a complete Protein

Answer 4

Contain All 20 amino acids (eggs, milk, meats, soybeans)

Question 5

Uses of protein in the body

Answer 5

Structural materials
Keratin (skin); collagen and elastin (connective tissue); muscle proteins
Functional molecules
Enzymes, some hormones
Amino acids can be burned for energy

Question 6

All-or-none rule

Answer 6

All amino acids needed must be present for protein synthesis

Question 7

Nitrogen balance

Answer 7

Rate of protein synthesis equals rate of breakdown
Positive nitrogen balance - synthesis exceeds breakdown (normal in children, pregnant women, tissue repair)
Negative nitrogen balance - breakdown exceeds synthesis (stress, burns, infection, injury, poor diet, starvation)

Question 8

Hormonal controls

Answer 8

Anabolic hormones (GH, sex hormones) accelerate protein synthesis and growth
Adrenal glucocorticoids (released during stress)  protein breakdown; conversion of amino acids to glucose

Question 9

Anabolism

Answer 9

synthesis of large molecules from small ones

Ex. Amino acids proteins

Question 10

Catabolism

Answer 10

hydrolysis of complex structures to simpler ones

Ex. Proteins amino acids

Question 11

Cellular respiration

Answer 11

Catabolism of food fuels capture of energy (ATP)
Enzymes shift high-energy phosphate groups of ATP to other molecules (phosphorylation) which are activated to perform cellular functions

Question 12

Oxidation

Answer 12

Loss of Hydrogen

Question 13

Reduction

Answer 13

Gain of Hydrogen

Question 14

Equation for oxidation of glucose

Answer 14

C6 H12 06 + 6O2 = 6Co2 + 6H2O + ATP

Question 15

Coenzymes

Answer 15

act as electron acceptors

NAD+ (H) [has electrons] & FAD

Question 16

Substrate-level phosphorylation

Answer 16

High energy phosphate group directly transferred to ADP, twice in glycolysis, once in Krebs Cycle.

Question 17

Oxidative Phosphorylation

Answer 17

Makes most of the ATP with Chemiosmotic pressure, with a buildup of proton concentration to build a gradient.

Question 18

Glucose enters cell by

Answer 18

Facilitated Diffusion and is phosphorylated to Glucose-6-phosphate

Question 19

How is glucose trapped in cell?

Answer 19

Most cells can’t reverse the action of glucose entering the cells, also the concentration gradient of glucose is always higher outside of cell so doesn’t want to leave.

Question 20

What cells can reverse the entering of glucose?

Answer 20

Intestine, kidney, liver cell

Question 21

Step 1: Glycolysis

Answer 21

Occurs in cytosol (anaerobic)
Starts with Glucose
Ends with 2 pyruvic acid, 2 NADH+H, net 2 ATP.

Question 22

Sugar Activation

Answer 22

Phosphorylation activates glucose converted to fructose-1 & 6-bisphosphate

Question 23

Sugar Cleavage

Answer 23

6-bisphosphate from Sugar activation is cleaved into 2 pieces

Question 24

Sugar Oxidation

Answer 24

Removal of Hydrogen

Question 25

Step after Glycolysis

Answer 25

Anaerobic - NADH gives H+ back to pyruvic acid reducing it to lactic acid Aerobic - Krebs Cycle in Mitochondria

Question 26

Transitional Phase

Answer 26

Convert each pyruvic acid to acetyl CoA in 3 steps. 1. A carboxyl group is removed from pyruvate releasing Co2. 2. NAD+ is reduced to NADH - oxidation reaction 3. An acetyl group is transferred to coenzyme and resulting to Acetyl CoA

Question 27

Krebs Cycle (citric acid cycle)

Answer 27

Occurs in mitochondria | Results in 8NADH +H+, 2 FADH2, 6Co2, 2 ATP

Question 28

Electron Transport Chain

Answer 28

Occurs in folds of mitochondria Complexes alternately reduce and oxidize as pick up and pass electrons to oxygen and form H2O. Hydrogen ion pumped to intermembrane space by respiratory enzymes complexes I, III & IV creates electrochemical proton gradient (change in pH) This is called oxidative phosphorylation

Question 29

Chemiosmosis

Answer 29

uses the proton gradient created by respiratory enzyme complexes I, III, IV, to synthesize ATP by having protons diffuse back through the matrix via a ATP synthase that creates and electrical current which creates the ATP

Question 30

Glycogenesis

Answer 30

Glycogen formation via glycogen synthase when glucose supplies exceed need for ATP synthesis Mostly in liver and skeletal muscle

Question 31

Glycogenolysis

Answer 31

Glycogen breakdown via glycogen phosphorylase in response to low blood glucose Only by hepatocytes, some kidney and intestinal cells

Question 32

Carbo loading

Answer 32

Carbohydrate-rich diet for 3-4 days; decreased activity - muscles store more glycogen - improved endurance

Question 33

Gluconeogenesis

Answer 33

Glucose formed in liver from glycerol and amino acids when blood glucose levels drop Protects nervous system and against damaging effects of hypoglycemia

Question 34

Why is glucose easily converted to Fat?

Answer 34

Because once it is converted to Acetyl CoA, it can then build up and if too many than can go to fat stores instead of back to glucose.

Question 35

Lipid Metabolism

Answer 35

Greater energy yield than from glucose or protein catabolism Most products of fat digestion transported in lymph as chylomicrons Hydrolyzed by endothelial enzymes into fatty acids and glycerol

Question 36

Lipogenesis

Answer 36

Glucose easily converted to fat because acetyl CoA is Intermediate in glucose catabolism Starting point for fatty acid synthesis

Question 37

Lipolysis

Answer 37

Stored fat glycerol, fatty acids for fuel Oxaloacetic acid necessary for complete oxidation of fat but converted to glucose if carbohydrates deficient Acetyl CoA is then converted by in liver to ketone bodies

Question 38

Ketosis

Answer 38

``` Accumulation of ketones in blood Ketones acidic - metabolic acidosis Breath smells fruity Rapid breath to release CO2, raise pH Common in starvation, dieting, diabetes Ketone bodies excreted in urine ```

Question 39

Protein Metabolism

Answer 39

• Proteins deteriorate, so continually broken down and replaced •Amino acids recycled -- new proteins • Protein not stored in body --When dietary protein in excess, amino acids are oxidized for energy or Converted to fat for storage

Question 40

3 steps of Oxidation of Amino Acids

Answer 40

Transamination - an amine group is switched from amino acid to Keto Acid. Oxidative Deamination - Amine group of glutamic Acid is removed as ammonia and combined w/ Co2 to form Urea - urine Keto Acid Modification - The keto acid formed during transamination are altered so they can easily enter the krebs cycle pathways.

Question 41

Absorptive State

Answer 41

Just Fed, anabolism exceeds catabolism

Question 42

Carbohydrates during Absorptive State

Answer 42

Glucose major fuel, glucose converted to glycogen or fat. synthesized fat & protein released to blood for storage by adipose as VLDL's.

Question 43

Triglycerides during Absorptive State

Answer 43

Lipoprotein lipase catalyze lipids of chylomicrons in muscle and fat tissue. Most glycerol and fatty acids converted to triglycerides for storage. Triglycerides used by adipose tissue, liver, skeletal, cardiac muscle as energy.

Question 44

Amino Acids during Absorptive State

Answer 44

To many - deaminate and used as ATP synthesis or stored fat. Aminos used in protein synthesis.

Question 45

What is happening Postabsorptive State

Answer 45

Under fed, catabolism of fat glycogen, and proteins exceeds anabolism. GOAL: maintain blood glucose, promotes use of fats for energy, save glucose for organs that need it most.

Question 46

Adipose tissue

Answer 46

It is innervated by sympathetic nervous system and supplies glucose if blood levels low.

Question 47

What do lipoproteins do?

Answer 47

Transport water - insoluble cholesterol and triglycerides in blood. Regulate lipid entry/exit at target cells.

Question 48

Roles of HDLs (GOOD)

Answer 48

Transport excessive cholesterol protein from peripheral tissues to liver to be broken down and secreted into bile and provide cholesterol to steroid-producing organs.

Question 49

Roles of LDLs

Answer 49

Transport cholesterol to tissues for membrane storage or hormone synthesis

Question 50

Roles of VLDLs

Answer 50

Transport triglycerides from liver to peripheral tissues (mostly adipose)

Question 51

Saturated Fatty Acids

Answer 51

Stimulate liver synthesis of cholesterol, inhibit cholesterol excretion from body. No double bonded carbons, solid at room temperature.

Question 52

Unsaturated Fatty Acids

Answer 52

Enhanced excretion of cholesterol enhancing cholesterol excretion to bile.

Question 53

What do Omega-3-Fatty Acids do?

Answer 53

Lower saturated fats and cholesterol, make platelets less sticky, help prevent spontaneous clotting, antiarrhythmic effects on heart, lower blood pressure.

Question 54

Long term regulators of food intake

Answer 54

Insulin & Leptin

Question 55

Leptin

Answer 55

Hormone secreted by fat cells in response to increased body fat mass. Indicator of energy stores. Rising the level of leptin has led to weight loss (idea)

Question 56

Basal Metabolic Rate

Answer 56

The energy need to perform essential activities. Recorded as kilocalories per square meter of body surface per hour (kcal/m2/h) BMR increases as ratio of body surface area to volume increases Decreases with age Males have higher BMR Increases with temperature or stress Thyroxine increases oxygen consumption, cellular respiration, and BMR Physical training has little effect on BMR

Question 57

Short Term regulators of food intake

Answer 57

• Neural signals from GI tract High protein content of meal increases and prolongs afferent vagal signals Distension sends signals along vagus nerve that suppress hunger center - Rising blood glucose - Elevated blood amino acid levels - Blood levels of fatty acids

Question 58

Total metabolic rate (TMR)

Answer 58

Rate of kilocalorie consumption to fuel all ongoing activities Increases with skeletal muscle activity and food ingestion (food-induced thermogenesis)

Question 59

Normal body temperature

Answer 59

``` 37C (98.6F) Optimal enzyme activity Increased temperature denatures proteins and depresses neurons Children <5 convulsions 41C(106F) ~43C (109F) - limit for life ```

Question 60

Mechanism of Heat Transfer

Answer 60

Evaporation - heat loss from water to body Radiation - loss of heat by infrared rays Conduction - transfer by direct contact Convection - transfer of heat to air (wind blowing)

Question 61

Insensible Heat Loss

Answer 61

Accompanies insensible water loss from lungs, oral mucosa, and skin

Question 62

Sensible Heat Loss

Answer 62

When body temp rises and sweating increases, water evaporates

Question 63

Related to Body temp, the Hypothalamus receives afferent input from what?

Answer 63

``` Peripheral thermoreceptors in shell (skin) Central thermoreceptors (some in HT) initiates appropriate heat-loss and heat-promoting activities. ```

Question 64

Heat-promoting mechanisms

Answer 64

Increase metabolic rate via Epinephrine and Norepinephrine. Chemical thermogenesis Enhanced thyroxine release Brown adipose tissue.

Question 65

Hyperthermia

Answer 65

Elevated body temp, tell HT to begin heat stroke

Question 66

Heat Exhaustion

Answer 66

Heat related collapse after hard exercise dehydration and low BP. Heat-loss mechanisms still functional, may turn to heat stroke.

Question 67

Hypothermia

Answer 67

Low body temp, shivering stops | can progress to coma and death at 21˚ c

Question 68

Controlled Hyperthermia

Answer 68

Fever

Question 69

What causes the symptoms of fever

Answer 69

Injured cells start releasing chemicals

Question 70

How does fever affect they hypothalamus

Answer 70

Resets the internal thermostat higher, temperature rises.

Question 71

PKU

Answer 71

Phenylketonuria - cells cannot use the amino acid phenylalanine. Neurotoxins in blood, brain damage, retardation.