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A+P 2 > chapter 24 > Flashcards

chapter 24 Flashcards

1
Q

nutrient
major nutrients
other nutrients

A

Nutrient: a substance in food that promotes normal growth, maintenance, and repair
Major nutrients
Carbohydrates, lipids, and proteins
Other nutrients
Vitamins and minerals (and, technically speaking, water)

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2
Q

Carbohydrates

dietary sources

A

Dietary sources

Starch (complex carbohydrates) 
grains and vegetables
Sugars 
fruits, sugarcane, sugar beets, honey and milk
Insoluble fiber
cellulose in vegetables
provides roughage
Soluble fiber: 
pectin in apples and citrus fruits
reduces blood cholesterol levels
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3
Q

Carbohydrates uses
Glucose fuel
Neurons and RBCs
Excess glucose is

A

Uses
Glucose fuel used by cells to make ATP
Neurons and RBCs rely almost entirely on glucose
Excess glucose is converted to glycogen or fat and stored

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4
Q

carbs dietary requirements

A

Dietary requirements
Minimum 100 g/day to maintain adequate blood glucose levels
Recommended minimum 130 g/day
Recommended intake: 45–65% of total calorie intake; mostly complex carbohydrates

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5
Q

lipids dietary sources

essentail fatty acids

A 
Dietary sources
Triglycerides
Saturated fats 
meat, dairy foods, and tropical oils
Unsaturated fats 
seeds, nuts, olive oil, and most vegetable oils
Cholesterol 
egg yolk, meats, organ meats, shellfish, and milk products

Essential fatty acids
Linoleic and linolenic acid,
in most vegetable oils
Must be ingested

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6
Q 
Lipids essential uses of lipids in the body
Help absorb
Major fuel of 
Phospholipids are essential in
functions of fatty deposits
Concentrated source of e
A

Essential uses of lipids in the body
Help absorb fat-soluble vitamins
Major fuel of hepatocytes and skeletal muscle
Phospholipids are essential in myelin sheaths and all cell membranes
Functions of fatty deposits (adipose tissue)
Protective cushions around body organs
Insulating layer beneath the skin
Concentrated source of energy

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7
Q

Lipids regulatory functions

functions of cholesterol

A 
Regulatory functions
Smooth muscle contraction
Control of blood pressure
Inflammation
Functions of cholesterol
Stabilizes membranes
Precursor of bile salts and steroid hormones
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8
Q

Lipids dietary requirements
Fats should represent
Saturated fats
Daily cholesterol intake

A

Dietary requirements suggested by the American Heart Association
Fats should represent 30% or less of total caloric intake
Saturated fats should be limited to 10% or less of total fat intake
Daily cholesterol intake should be no more than 300 mg

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9
Q

Proteins Dietary sources

and dietary requirements and uses

A

Dietary sources
Eggs, milk, fish, and most meats
Legumes, nuts, and cereals contain incomplete proteins (lack some essential amino acids)
Legumes and cereals together contain all essential amino acids
Dietary requirements
Rule of thumb: daily intake of 0.8 g per kg body weight
Uses
Structural materials
keratin, collagen, elastin, muscle proteins
Most functional molecules
enzymes, some hormones

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10
Q

use of amino acids in the body

A

Use of amino acids in the body
1. All-or-none rule
All amino acids needed must be present for protein synthesis to occur

2.Adequacy of caloric intake
Protein will be used as fuel if there is insufficient carbohydrate or fat available

  1. Nitrogen balance
    State where the rate of protein synthesis equals the rate of breakdown and loss
    Positive if synthesis exceeds breakdown (normal in children and tissue repair)
    Negative if breakdown exceeds synthesis (e.g., stress, burns, infection, or injury)
4.Hormonal controls
Anabolic hormones (GH, sex hormones) accelerate protein synthesis
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11
Q

Vitamins
Crucial in
Most function as

A

Organic compounds
Crucial in helping the body use nutrients
Most function as coenzymes
Vitamins D, some B, and K are synthesized in the body

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12
Q

Vitamins two types based on ____

A 
Two types, based on solubility
Water-soluble vitamins
B complex and C are absorbed with water
B12 absorption requires intrinsic factor
Not stored in the body 
Fat-soluble vitamins
A, D, E, and K are absorbed with lipid digestion products
Stored in the body, except for vitamin K
Vitamins A, C, and E act as antioxidants
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13
Q

Minerals
Work with
Uptake and excretion must be

A

Seven required in moderate amounts:
Calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium
Others required in trace amounts
Work with nutrients to ensure proper body functioning
Uptake and excretion must be balanced to prevent toxic overload

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14
Q 
minerals examples
harden bone
essential for oxygen binding to hemoglobin
necessary for thyroid hormone synthesis
major electrolytes in the blood
A

Examples
Calcium, phosphorus, and magnesium salts harden bone
Iron is essential for oxygen binding to hemoglobin
Iodine is necessary for thyroid hormone synthesis
Sodium and chloride are major electrolytes in the blood

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15
Q

Metabolism

A

Metabolism
biochemical reactions inside cells involving nutrients
Two types of reactions
Anabolism
synthesis of large molecules from small ones
Catabolism
hydrolysis of complex structures to simpler ones

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16
Q

Cellular respiration
Enzymes shift
Phosphorylated molecules are

A

Cellular respiration
catabolism of food fuels and capture of energy to form ATP in cells
Enzymes shift high-energy phosphate groups of ATP to other molecules (phosphorylation)
Phosphorylated molecules are activated to perform cellular functions

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17
Q

Stages of metabolism

A

Processing of nutrients
1. Digestion, absorption and transport to tissues

2.Cellular processing (in cytoplasm)
Synthesis of lipids, proteins, and glycogen (anablolism)
Catabolism (glycolysis) into intermediates

3.Oxidative (mitochondrial) breakdown of intermediates into CO2, water, and ATP

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18
Q

Oxidation-Reduction (Redox) Reactions
Oxidized substances
Reduced substances
Coenzymes act as

A

Oxidation
gain of oxygen or loss of hydrogen
Oxidation-reduction (redox) reactions
Oxidized substances lose electrons and energy
Reduced substances gain electrons and energy
Coenzymes act as hydrogen (or electron) acceptors
Nicotinamide adenine dinucleotide (NAD+)
Flavin adenine dinucleotide (FAD)

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19
Q

ATP Synthesis two mechanisms

A

Two mechanisms
Substrate-level phosphorylation
Oxidative phosphorylation

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20
Q

Substrate-Level Phosphorylation

occurs in

A

High-energy phosphate groups directly transferred from phosphorylated substrates to ADP
Occurs in glycolysis and the Krebs cycle
Also occurs in certain muscle fibers

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21
Q

Oxidative Phosphorylation
_____ Process
occurs only in the

A

Chemiosmotic process
Couples the movement of substances across a membrane to chemical reactions
In the mitochondria
Carried out by electron transport proteins
Nutrient energy is used to create H+ gradient across mitochondrial membrane
H+ flows through ATP synthase
Energy is captured and attaches phosphate groups to ADP
We will look more closely at this in a few minutes when we discuss electron transport.

  • Electron trasport protein “pump” protons, creating a proton gradient.
  • ATP synthase uses the energy of the proton gradient to bind phosphate groups to ADP
  • Occurs only in the mitochondrial matrix
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22
Q

Carbohydrate Metabolism

Glucose is catabolized in three pathways

A

Oxidation of glucose
C6H12O6 + 6O2  6H2O + 6CO2 + 36 ATP + heat
Glucose is catabolized in three pathways (3 steps to cellular respiration)
Glycolysis
Krebs cycle
Electron transport chain and oxidative phosphorylation

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23
Q 
Glycolysis
\_\_ step pathway
occurs in \_\_\_
\_\_->\_\_\_
three major phases
A 
10-step pathway
Anaerobic
Occurs in the cytosol
Glucose → 2 pyruvic acid molecules
Three major phases
Sugar activation
Sugar cleavage
Sugar oxidation and ATP formation
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24
Q

phase 1 sugar activation

A

phosphorylation activates glucose. Glucose is converted to fructose-1,6-biphophate. 2 ATP molecules are used

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25
Q

Phase 2 Sugar cleavage:

A

fructose-1,6-biphophate is split into two 3-carbon fragments

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26
Q

Phase 3 sugar oxidation and ATP formation

A

the 3-carbond fragments are oxidized (by removing hydrogen) and 4 ATP molecules are formed

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27
Q 
final products of glycolysis
Converted to lactic acid if
Enter aerobic pathways if
2 NADH + H+ (reduced 
Net gain of
A

Final products of glycolysis
2 pyruvic acid
Converted to lactic acid if O2 not readily available
Enter aerobic pathways if O2 is readily available
2 NADH + H+ (reduced NAD+)
Net gain of 2 ATP

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28
Q

Krebs Cycle

occurs in the 
fueled by 
transitional phase
Each pyruvic acid is converted to 
Decarboxylation: 
Oxidation, H+ is removed from
Acetic acid + coenzyme A =
A

Occurs in mitochondrial matrix
Fueled by pyruvic acid and fatty acids

Transitional phase
Each pyruvic acid is converted to acetyl CoA
Decarboxylation: removal of 1 C to produce acetic acid and CO2
Oxidation: H+ is removed from acetic acid and picked up by NAD+
Acetic acid + coenzyme A forms acetyl CoA

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29
Q

Coenzyme A shuttles acetic acid to an

Each acetic acid is

A

Coenzyme A shuttles acetic acid to an enzyme of the Krebs cycle
Each acetic acid is decarboxylated and oxidized, generating:
3 NADH + H+
1 FADH2
2 CO2
1 ATP

30
Q

Krebs cycle does not what?
Breakdown products of
Cycle intermediates may be used as

A

Does not directly use O2
Breakdown products of fats and proteins can also enter the cycle
Cycle intermediates may be used as building materials for anabolic reactions

31
Q

Electron Transport Chain and Oxidative Phosphorylation

The part of metabolism that directly
Chain of proteins bound to
Substrates NADH + H+ and FADH2 deliver

A

The part of metabolism that directly uses oxygen
Chain of proteins bound to metal atoms (cofactors) on inner mitochondrial membrane, cristae)
Substrates NADH + H+ and FADH2 deliver hydrogen atoms

32
Q

Electron Transport Chain and Oxidative Phosphorylation

Hydrogen atoms are
Electrons are shuttled along the
Released energy is used to

Respiratory enzyme complexes I, III, and IV pump
H+ diffuses back to the
ATP synthase uses released energy to make

Electrons are delivered to
O– attracts

A

Hydrogen atoms are split into H+ and electrons
Electrons are shuttled along the inner mitochondrial membrane, losing energy at each step
Released energy is used to pump H+ into the intermembrane space

Respiratory enzyme complexes I, III, and IV pump H+ into the intermembrane space
H+ diffuses back to the matrix via ATP synthase
ATP synthase uses released energy to make ATP

Electrons are delivered to O, forming O–
O– attracts H+ to form H2O

33
Q

Electronic Energy Gradient

This energy is released in a stepwise manner through th

A

Transfer of energy from NADH + H+ and FADH2 to oxygen releases large amounts of energy
This energy is released in a stepwise manner through the electron transport chain

34
Q

Glycogenesis and Glycogenolysis

A

Glycogenesis
Glycogen formation when glucose supplies exceed need for ATP synthesis
Mostly in liver and skeletal muscle
Glycogenolysis
Glycogen beakdown in response to low blood glucose

35
Q

Gluconeogenesis

Mainly in the
Protects against

A

Glucose formation from noncarbohydrate (glycerol and amino acid) molecules
Mainly in the liver
Protects against damaging effects of hypoglycemia

36
Q 
Lipid Metabolism
Fat catabolism yields
Most products of fat digestion are 
 Only triglycerides are routinely
The two building blocks are oxidized separately
A

Fat catabolism yields 9 kcal per gram (vs 4kcal per gram of carbohydrate or protein)
Most products of fat digestion are hydrolyzed by endothelial enzymes into fatty acids and glycerol
Only triglycerides are routinely oxidized for energy
The two building blocks are oxidized separately
Glycerol pathway
Fatty acid pathway

37
Q

Lipogenesis

occurs when cellular ___ and ___ are ___

Glucose is easily converted into fat because acetyl CoA is

A

Triglyceride synthesis occurs when cellular ATP and glucose levels are high
Glucose is easily converted into fat because acetyl CoA is
An intermediate in glucose catabolism
A starting point for fatty acid synthesis

38
Q

Lipolysis
Oxaloacetic acid is necessary for
Without it, acetyl CoA is converted

A

The reverse of lipogenesis
Oxaloacetic acid is necessary for complete oxidation of fat
Without it, acetyl CoA is converted by ketogenesis in the liver into ketone bodies (ketones)

39
Q 
Synthesis of Structural Materials
Phospholipids for
Cholesterol for 
In the liver synthesis of transport of 
Synthesis of cholesterol from 
Use of cholesterol to form
A

Phospholipids for cell membranes and myelin
Cholesterol for cell membranes and steroid hormone synthesis
In the liver
Synthesis of transport lipoproteins for cholesterol and fats
Synthesis of cholesterol from acetyl CoA
Use of cholesterol to form bile salts

40
Q

Protein Metabolism

When dietary protein is in excess, amino acids are

A

When dietary protein is in excess, amino acids are
Oxidized for energy
Converted into fat for storage

41
Q

Protein Synthesis
is ___ controlled
requires a ___ of amino acids
essentail amino acids must be provided in ___

A

Is hormonally controlled
Requires a complete set of amino acids
Essential amino acids must be provided in the diet

42
Q

Catabolic-Anabolic Steady State

A

A dynamic state in which
Organic molecules (except DNA) are continuously broken down and rebuilt
Organs have different fuel preferences

43
Q

Absorptive and Postabsorptive States

A 
Absorptive (fed) state
During and shortly after eating
Absorption of nutrients is occurring
Postabsorptive (fasting) state
When the GI tract is empty 
Energy sources are supplied by breakdown of reserves
44
Q

Sources of Blood Glucose Postabsorpative
Glycogenolysis in the ___ and ___

Lipolysis in ____ and ____
Catabolism of cellular protein during
Amino acids are deaminated and used for gluconeogenesis in the ___ and later in the _____

A

Glycogenolysis in the liver
Glycogenolysis in skeletal muscle
Lipolysis in adipose tissues and the liver
Glycerol is used for gluconeogenesis in the liver
Catabolism of cellular protein during prolonged fasting
Amino acids are deaminated and used for gluconeogenesis in the liver and (later) in the kidneys

45
Q

Postabsorptive State: Hormonal Controls

Glucagon release is stimulated by
Glucagon, a hyperglycemic hormone, promotes

A

Glucagon release is stimulated by
Declining blood glucose
Rising amino acid levels

Glucagon, a hyperglycemic hormone, promotes
Glycogenolysis and gluconeogenesis in the liver
Lipolysis in adipose tissue
Modulation of glucose effects after a high-protein, low-carbohydrate meal

46
Q

Postabsorptive State: Neural Controls

A

In response to low plasma glucose, or during fight-or-flight or exercise, the sympathetic nervous system and epinephrine from the adrenal medulla promote
Fat mobilization
Glycogenolysis

47
Q

Metabolic Role of the Liver

Process nearly every
Play a major role in regulating plasma
Store
Metabolize

A

Hepatocytes (liver cells)
Process nearly every class of nutrient
Play a major role in regulating plasma cholesterol levels
Store vitamins and minerals
Metabolize alcohol, drugs, hormones, and bilirubin

48
Q 
Cholesterol
Structural basis of 
Major component of 
Makes up part of the
Transported in
A

Structural basis of bile salts, steroid hormones, and vitamin D
Major component of plasma membranes
Makes up part of the hedgehog signaling molecule that directs embryonic development
Transported in lipoprotein complexes containing triglycerides, phospholipids, cholesterol, and protein

49
Q

Lipoproteins

A 
Types of lipoproteins
HDLs (high-density lipoproteins)
The highest protein content
LDLs (low-density lipoproteins)
Cholesterol-rich
VLDLs (very low density lipoproteins)
Mostly triglycerides
Chylomicrons
50
Q

High levels of HDL are thought to

High levels of LDL, especially lipoprotein (a) increase the risk of

A

High levels of HDL are thought to protect against heart attack
High levels of LDL, especially lipoprotein (a) increase the risk of heart attack

51
Q

Plasma Cholesterol Levels

The liver produces cholesterol
Saturated fatty acids
Unsaturated fatty acids
Trans fats

A

The liver produces cholesterol
At a basal level regardless of dietary cholesterol intake
In response to saturated fatty acids

Saturated fatty acids
Stimulate liver synthesis of cholesterol
Inhibit cholesterol excretion from the body

Unsaturated fatty acids
Enhance excretion of cholesterol

Trans fats
Increase LDLs and reduce HDLs

52
Q

Unsaturated omega-3 fatty acids (found in cold-water fish)

A

Unsaturated omega-3 fatty acids (found in cold-water fish)
Lower the proportions of saturated fats and cholesterol
Have antiarrhythmic effects on the heart
Help prevent spontaneous clotting
Lower blood pressure

53
Q

Non-Dietary Factors Affecting Cholesterol

stress smoking cigs
aerobic exercise
apple
pear

A

Stress, cigarette smoking, and coffee lower HDL levels
Aerobic exercise and estrogen increase HDL levels and decrease LDL levels
Body shape
“Apple”: Fat carried on the upper body is correlated with high cholesterol and LDL levels
“Pear”: Fat carried on the hips and thighs is correlated with lower cholesterol and LDL levels

54
Q

Energy Balance

A

Bond energy released from food must equal the total energy output
Energy intake = the energy liberated during food oxidation
Energy output
Immediately lost as heat (~60%)
Used to do work (driven by ATP)
Stored as fat or glycogen

55
Q

heat energy

A

Heat energy
Cannot be used to do work
Warms the tissues and blood
Helps maintain the homeostatic body temperature
Allows metabolic reactions to occur efficiently

56
Q

Obesity

A

Body mass index (BMI) = 
wt (lb) × 705/ht (inches)2
Considered overweight if BMI is 25 to 30
Considered obese if BMI is greater than 30
Higher incidence of atherosclerosis, diabetes mellitus, hypertension, heart disease, and osteoarthritis

57
Q

Long-Term Regulation of Food Intake

additional factors

A 
Additional factors
Temperature
Stress
Psychological factors
Adenovirus infections
Sleep deprivation
58
Q

Metabolic Rate

A

Total heat produced by chemical reactions and mechanical work of the body
Measured directly with a calorimeter or indirectly with a respirometer
Basal metabolic rate (BMR)
Reflects the energy the body needs to perform its most essential activities

59
Q

Factors that Influence BMR
As the ratio of body surface area to volume increases, BMR
_____ with age
______with temperature or stress

A

As the ratio of body surface area to volume increases, BMR increases
Decreases with age
Increases with temperature or stress
Males have a disproportionately higher BMR
Thyroxine increases oxygen consumption, cellular respiration, and BMR

60
Q

total Metabolic Rate

A

Total metabolic rate (TMR)
Rate of kilocalorie consumption to fuel all ongoing activities
Increases with skeletal muscle activity and food ingestion

61
Q

Regulation of Body Temperature
At rest,
During exercise, heat production from

A

Body temperature reflects the balance between heat production and heat loss
At rest, the liver, heart, brain, kidneys, and endocrine organs generate most heat
During exercise, heat production from skeletal muscles increases dramatically

62
Q

Regulation of Body Temperature
normal body temp
optimal enzyme activity occurs
increased temp ___

A

Normal body temperature = 37°C (98.6°F)
Optimal enzyme activity occurs at this temperature
Increased temperature denatures proteins and depresses neurons

63
Q

Mechanisms of Heat Exchange

four mechanisms

A

Four mechanisms
Radiation is the loss of heat in the form of infrared rays
Conduction is the transfer of heat by direct contact
Convection is the transfer of heat to the surrounding air
Evaporation is the heat loss due to the evaporation of water from body surfaces

64
Q

Core and Shell Temperature
_____ is the major agent of heat exchange between the core and the shell
Core temperature vs. shell temperature

A

Organs in the core have the highest temperature
Blood is the major agent of heat exchange between the core and the shell
Core temperature is regulated
Core temperature remains relatively constant, while shell temperature fluctuates substantially (20°C–40°C)

65
Q

Mechanisms of Heat Exchange

Insensible heat loss accompanies insensible
Evaporative heat loss becomes sensible (active) when body temperature

A

Insensible heat loss accompanies insensible water loss from lungs, oral mucosa, and skin
Evaporative heat loss becomes sensible (active) when body temperature rises and sweating increases water vaporization

66
Q

Hyperthermia
depresses the
(heat stroke) begins at core temperature of ___

A

Hyperthermia
Elevated body temperature depresses the hypothalamus
Positive-feedback mechanism (heat stroke) begins at core temperature of 41°C
Can be fatal if not corrected

67
Q

hyporthermia

Shivering stops at core temperature of

A

Hypothermia
Low body temperature where vital signs decrease
Shivering stops at core temperature of 30 - 32°C
Can progress to coma a death by cardiac arrest at ~ 21°C

68
Q

Heat exhaustion

A

Heat exhaustion
Heat-associated collapse after vigorous exercise
Due to dehydration and low blood pressure
Heat-loss mechanisms are still functional
May progress to heat stroke

69
Q

hypothermia

A

Hypothermia
Low body temperature where vital signs decrease
Shivering stops at core temperature of 30 - 32°C
Can progress to coma a death by cardiac arrest at ~ 21°C

70
Q

fever

A

Controlled hyperthermia

Due to infection (also cancer, allergies, or CNS injuries)

A+P 2 (13 decks)

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