Download Chapter 23 Respiratory System Functions: Provides for gas

Chapter 23 Respiratory System
Functions:
1. Provides for gas exchange- intake of O2 for delivery to body cells and elimination of CO2 produced
by body cells
2. Helps regulate pH
3. Contains receptors for the sense of smell, filters inspired air, produces vocal sounds, and excretes
small amount of water and heat.
Structurally
Upper respiratory system
Lower respiratory system
Functionally
Conducting zone – conducts air to lungs
Respiratory zone – main site of gas exchange
NOSE
Functions:
1. ________________________________________
2. ________________________________________
3. ________________________________________
Pseudostratified Ciliated Columnar Epithelia
PHARYNX
Starts at internal nares and extends to cricoid cartilage of larynx
Contraction of skeletal muscles assists in deglutition
Functions:
1. Passageway for air and food
2. Resonating chamber
3. Houses tonsils
3 anatomical regions
Nasopharynx - Nose - Soft palate
Oropharynx – Soft Palate – Hyoid Bone
Laryngopharynx - Hyoid Bone - Esophagus
LARYNX
9 pieces of cartilage:
Thyroid cartilage or Adam’s apple
Cricoid cartilage hallmark for ____________________________________(see figure
23.4)
Epiglottis closes off glottis during swallowing
Glottis – pair of folds of mucous membranes, vocal folds
False vocal cords– superior pair, Hold breath
True vocal cords– inferior pair, Vibrate and produce sound with air
_______________________– inflammation of the larynx most often
caused by a respiratory infection or irritants such as cigarette
smoke.
Symptoms: Fever, Hoarseness, Swollen lymph nodes or glands in
the neck
TRACHEA
Extends from larynx to superior border of T5
Divides into right and left _______________________________
16-20 C-shaped rings of hyaline cartilage
BRONCHIOLES
Right – more vertical, shorter, wide leads to 3 lobes of lung
Left – leads to 2 lobes of lung
LUNGS
Each lung enclosed by double-layered pleural membrane
__________________________ – lines wall of thoracic cavity
__________________________ – covers lungs themselves
Pleural cavity is space between layers
Pleural fluid reduces friction, produces surface tension (stick together)
Cardiac notch – heart makes left lung 10% smaller than right
Carina – Sensitive area cough
Alveoli
2 types of alveolar epithelial cells
Type I alveolar cells –main site of
_____________________
Type II alveolar cells- secrete alveolar fluid
Very thin – only 0.5 µm thick to allow rapid
diffusion of gases
Lungs receive blood from
________________________ - deoxygenated blood
_____________________________ – oxygenated blood to
perfuse muscular walls of bronchi and bronchioles
Pulmonary Ventilation
Respiration (gas exchange) steps
1. Pulmonary ventilation/ breathing
Inhalation and exhalation
Exchange of air between atmosphere and alveoli
2. External (pulmonary) respiration
Exchange of gases between alveoli and blood
3. Internal (tissue) respiration
Exchange of gases between systemic capillaries and
tissue cells
Supplies cellular respiration (makes ATP)
1. Inhalation
Inhalation is _________________ – Contraction of
 __________________________– most important
muscle of inhalation
Responsible for 75% of air entering lungs
during normal quiet breathing
 ___________________________- Contraction
elevates ribs
25% of air entering lungs during normal
quiet breathing
Accessory muscles for deep, forceful
inhalation
2. Exhalation
Pressure in lungs is _____________than
atmospheric pressure
Normally _____________________ – muscle relax
instead of contract
- elastic recoil
- Diaphragm relaxes
- External intercostals relax
Exhalation only active during forceful
breathing
Inhalation
Pressure inside alveoli must become lower than atmospheric
pressure for air to flow into lungs
760 millimeters of mercury (mmHg) or 1 atmosphere (1 atm)
Achieved by increasing size of lungs
Boyle’s Law – pressure of a gas in a closed container is inversely
proportional to the volume of the container
Air Flow
Air pressure differences drive airflow
3 other factors affect rate of airflow and ease of pulmonary ventilation
1. Surface tension of alveolar fluid
Causes alveoli to assume smallest possible diameter
Accounts for 2/3 of lung elastic recoil
Prevents collapse of alveoli at exhalation
2. Lung compliance
High compliance means lungs and chest wall expand easily
Related to elasticity and surface tension
3. Airway resistance
Larger diameter airway has less resistance
Regulated by diameter of bronchioles & smooth muscle tone
Lung Volumes and Capacities
_____________________________________ (MV) = total volume of air inhaled and exhaled each minute
Normal healthy adult averages 12 breaths per minute
moving about 500 ml of air in and out of lungs (tidal volume)
MV = 12 breaths/min x 500 ml/ breath
= 6 liters/ min
Notes on Board:
Problems:
1. Joan’s total volume from one breath is 450ml and she averages 13breaths/min.
What is her minute ventilation?
What is her tidal Volume?
What is her aveolar ventilation rate?
2. Jill has a minute ventilation of 6000ml/min and she averages 11 breaths/min.
What is her Tidal volume?
That is the anatomic dead space volume?
What is the alveolar ventilation rate?
3. Bill’s Tidal volume is 500ml, his functional residual volume is 2400ml, and his inspiratory
capacity is 3200ml.
What is Bill’s inspritory reserve volume?
What is Bill’s total lung capacity?
4. Mark has a tidal volume of 430ml and averages 12breaths/ min.
What is Mark’s minute ventilation?
What is Mark’s anatomic dead space volume?
What should Mark’s weight average if he is in good shape?
5. Martha has an expiratory reverve volume of 1101ml, and a residual volume of 1100ml.
What is Matha’s functional residual volume?
What is the importance of the functional residual volume?
Dalton’s Law
-Each gas in a mixture of gases exerts its own pressure as if no other gases were present
-Atmospheric pressure (________________ mmHg) = PN2 + PO2 + PH2O + PCO2 + Pother gases
-Partial pressure greater  Partial pressure less
- The greater the difference, the faster the rate of diffusion
Henry’s law
-Quantity of a gas that will dissolve in a liquid is proportional to the partial pressures of the gas and its
solubility
-Higher partial pressure of a gas over a liquid and higher solubility, more of the gas will stay in solution
-CO2 is 24 times more soluble than O2
External Respiration vs. Internal Respiration
At rest, only about ________% of the available
oxygen is used
Deoxygenated blood would retain _________%
of its oxygen capacity
Rate of Pulmonary and Systemic
Gas Exchange
Depends on:
1. _____________________________________
Alveolar PO2 must be higher than blood PO2
for diffusion to occur – problem with
increasing altitude
2. _____________________________________
3. ______________________________________
occurs before hypercapnia
Oxygen transport
1.5% dissolved in plasma
98.5% bound
Heme
Oxyhemoglobin
Only dissolved portion can diffuse out of blood into
cells
Oxygen must be able to bind and dissociate from
heme
4. ____________________________________
O2 has a lower molecular weight and should
diffuse faster than CO2 except for its low
solubility - when diffusion is slow, hypoxia
Relationship between Hemoglobin and Oxygen Partial Pressure
Higher the PO2, More O2 combines with Hb
Fully saturated –
Percent saturation expresses average saturation of hemoglobin with oxygen
Oxygen-hemoglobin dissociation curve
 In pulmonary capillaries, O2 loads onto Hb
 In tissues, O2 is not held and unloaded
75% may still remain in deoxygenated blood (reserve)
Oxygen-hemoglobin Dissociation Curve
Hemoglobin and Oxygen
Other factors affecting affinity of Hemoglobin for
oxygen
Each makes sense if you keep in mind that
metabolically active tissues need O2, and produce
acids, CO2, and heat as wastes
1. __________________________
2. __________________________
3. __________________________
Bohr Effect
-As acidity increases (pH decreases), affinity of Hb
for O2 decreases
Increasing acidity enhances unloading
Shifts curve to right
-PCO2
Also shifts curve to right
As PCO2 rises, Hb unloads oxygen more easily
Low blood pH can result from high PCO2
-Temp
Within limits, as temperature increases, more oxygen is released from HbqDuring hypothermia, more
oxygen remains bound
2,3-bisphosphoglycerate
BPG formed by red blood cells during glycolysis
Helps unload oxygen by binding with Hb
Fetal hemoglobin
Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin
Hb-F can carry up to 30% more oxygen
Maternal blood’s oxygen readily transferred to fetal blood
Carbon Dioxide Transport
Dissolved CO2
Smallest amount, about 7%
Carbamino compounds
About 23% combines with amino acids including those in Hb
Carbaminohemoglobin
Bicarbonate ions
70% transported in plasma as HCO3Enzyme carbonic anhydrase forms carbonic acid (H2CO3) which dissociates into H+ and HCO3-
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3Chloride shift
HCO3- accumulates inside RBCs as they pick up carbon dioxide
Some diffuses out into plasma
To balance the loss of negative ions, chloride (Cl-) moves into RBCs from plasma
Reverse happens in lungs – Cl- moves out as moves back into RBCs
Chapter 24: The Digestive System
6 functions of the digestive system
1. ___________________________
2. ___________________________ of water, acid, buffers, and enzymes into lumen
3. ___________________________
4. ___________________________
- Mechanical digestion churns food
- Chemical digestion – hydrolysis
5. ___________________________ – passing into blood or lymph
6. ___________________________ – elimination of feces
2 groups of organs compose the digestive system
A. Gastrointenstinal (GI) tract or alimentary canal –
B. Accessory digestive organs –
Organs of the digestive system Fig 24.4
Layers of the GI tract
Wall of GI tract from lower esophagus to anal canal has same basic
4 layers
1. ___________________________ – inner lining
a. Epithelia -b. Lamina Propria –
c. Muscularis Mucosa –
2. ___________________________
3. ___________________________
Voluntary skeletal muscle found in mouth, pharynx, upper 2/3 of esophagus, and anal sphincter
Involuntary smooth muscle elsewhere
4. ___________________________
Outermost covering of organs suspended in abdominopelvic cavity
Esophagus lacks serosa – has adventitia
Peritoneum
Largest serous membrane of the body
Divided into
Parietal peritoneum –
Visceral peritoneum –
5 major peritoneal folds
-Greater omentum
-falciform ligament
-lesser omentum
-mesentery
-mesocolon
Mouth
Oral Cavity
Mechanical Digestion
-Mastication
Chemical Digestion
Saliva
Mostly water 99.5%
0.5% solutes – ions, dissolved gases, urea, uric acid, mucus, immunoglobulin A, lysozyme, and salivary
amylase (acts on starch)
Salivation6 glands 3 pairs
1) __________________:
- located anterior and inferior to ear
- produce salivary amylase
2) __________________ :
- medial inferior to mandible
-buffer, mucin, salivary amylase
3) __________________
beneath the tongue
- buffer, mucin, salivary amylase
Tongue and Teeth
Tongue
-Accessory digestive organ
Lingual gland – ___________________
Teeth (Fig 24.8)
- Accessory digestive organ
- 3 major regions – crown, root, and neck (label in image)
Dentin of crown covered by enamel
2 dentitions – deciduous and permanent teeth
Deglutition 9 sec to reach stomach
Act of swallowing
Facilitated by secretions of saliva and mucus
Involves mouth, pharynx, and esophagus
3 stages
 Voluntary – bolus passed to oropharynx
 Pharyngeal – involuntary passage through pharynx into esophagus
 Esophageal – involuntary passage
through esophagus to stomach
Esophagus
Secretes mucous, transports food – no
enzymes produced, no absorption
Peristalsis –
Esophageal Sphincter
Stomach
Serves as mixing chamber and holding
reservoir
4 main regions
1. ___________________ – smallest part of the
stomach, mucus glands to prevent acid
damage
2. ___________________ – upper bulge
3. ___________________ - largest region of the
stomach, gastric glands
4. ___________________ – is the curve of the J,
region that connects the
stomach to the duodenum
Gastric Glands of the Fundus
and Body
Gastric Glands
______________________: HCl and
Intrinsic Factor which facilitates
the absorption of Vitamin B12
(hematopoiesis)
- H and Cl are independent
pH _________________
_____________________:
- most abundant neat the base of
gastric gland
- secrete _______________________
- secrete gastric lipase
- in newborn secretes rennin
and gastric lipase to digest milk
Pancreas
Histology
99% of cells are acini
Exocrine
Secrete pancreatic juice
1% of cells are pancreatic islets (islets of Langerhans)
Endocrine
Secrete hormones
Pancreatic juice
1200-1500ml daily
Mostly water
Sodium bicarbonate – buffers acidic stomach chyme
Enzymes
Liver
Liver is the heaviest gland of the body
Liver is composed of
Hepatocytes – major functional cells of liver
Bile canaliculi – ducts between hepatocytes that collect bile
Exits livers as common hepatic duct,
joins cystic duct from gallbladder
to form common bile duct
see page 949 for list of liver functions
Gallbladder
Storage of Bile produced by Liver
Contraction bilecystic duct
Bile- bile salts, water, cholesterol, bile pigments, ions
pH - 7.6-8.6
Hepatic Blood Flow
Small intestine
3 regions:
1. _____________________ – 10 inches, the shortest region, from pyloric sphincter to jejunum
2. _____________________ – 3 ft. From duodenum to ileum
3. _____________________ – 6ft, joins to large intestine called the iliocecal sphincter
Special structural features increase surface area for digestion and absorption
 -Circular folds
 -_____________- Contains arteriole, venule, blood capillary, and lacteal
 -______________ - Projects of apical membrane of absorptive cells,
Intestinal juice and brush-border enzymes
Brush border enzymes
Inserted into plasma membrane of absorptive cells
Some enzymatic digestion occurs at surface rather than just in lumen
α-dextrinase, maltase, sucrase, lactase, aminopetidase, dipeptidase, nucleosidases and phosphatases
Chemical digestion

Carbohydrates
Pancreatic amylase
α-dextrinase, sucrase, lactase, maltase in brush border
Ends with monosaccharides which can be absorbed

Proteins
Trypsin, chymotrypsin, carboxypeptidase, and elastase from pancreas
Aminopeptidase and dipeptidase in brush border

Lipids
Pancreatic lipase most important in triglyceride digestion
Emulsification by bile salts increases surface area
Amphipathic – hydrophobic and hydrophilic regions

Nucleic acids
Ribonuclease and deoxyribonuclease in pancreatic juice
Nucleosidases and phosphatases in brush border
Large intestine
Overall function to complete absorption, produce certain vitamins, and form and expel feces
4 major regions
1. Cecum – expanding pouch, contain the appendix
2. Colon –
 Ascending
 Transverse
 Descending
 Sigmoid
3. Rectum – (Last 15cm of digestive tract)
 Internal sphincter – involuntary
 External sphincter – voluntary
4. Anus
Mechanical digestion
Haustral churning
Peristalsis
Mass peristalsis – drives contents of colon toward rectum
Chemical digestion
Final stage of digestion through bacterial action
Ferment carbohydrates, produce some B vitamins and vitamin K
Mucus but no enzymes secreted
Remaining water absorbed along with ions and some vitamins
Chapter 25: Metabolism and Nutrition
 Metabolism – refers to all chemical reaction occurring in body
 Catabolism – break down complex molecules
 _________________– produce more energy than they consume
 Anabolism – combine simple molecules into complex ones
 __________________- consume more energy than they produce
 Adenosine triphosphate (_______)
 “energy currency”
 ADP + P + energy ↔ ATP

Role of ATP in linking anabolic and catabolic reactions
 Energy transfer
 Oxidation-reduction or redox reactions
 Oxidation – removal of electrons
 Decrease in potential energy
 Dehydrogenation – removal of hydrogens
 Liberated hydrogen transferred by coenzymes
 Nicotinamide adenine dinucleotide (NAD)
 Flavin adenine dinucleotide (FAD)
 Glucose is oxidized
 Reduction – addition of electrons
 Increase in potential energy
 3 Mechanisms of ATP generation
1. ______________________________
 Transferring high-energy phosphate group from an intermediate directly to ADP
2. _______________________________
 Remove electrons and pass them through electron transport chain to oxygen
3. _______________________________
 Only in chlorophyll-containing plant cells
Carbohydrate metabolism
 Fate of glucose depends on needs of body cells
 ATP production or synthesis of amino acids, glycogen, or triglycerides
 GluT transporters bring glucose into the cell via facilitated diffusion
 Insulin causes insertion of more of these transporters, increasing rate of entry into cells
 Glucose trapped in cells after being phosphorylated
 Glucose catabolism / cellular respiration
 Glycolysis
 __________________________ respiration – does not require oxygen
 Formation of acetyl coenzyme A
 Krebs cycle reactions
 Electron transport chain reactions
 Aerobic respiration – requires oxygen
Overview of cellular respiration
1. Glycolysis
 Splits 6-carbon glucose into 2 3-carbon molecules of pyruvic acid
 Consumes 2 ATP but generates 4
 10 reactions
 Fate of pyruvic acid depends on oxygen availability
- If oxygen is scarce (_________________), reduced to lactic acid
- ______________________ can convert it back to pyruvic acid
- If oxygen is plentiful (aerobic), converted to acetyl coenzyme A
 Cellular respiration begins with glycolysis
 The 10 reactions of glycolysis
2. Formation of Acetyl coenzyme A
 Each pyruvic acid converted to 2-carbon acetyl group
 Remove one molecule of CO2 as a waste product
 Each pyruvic acid also loses 2 hydrogen atoms
 NAD+ reduced to NADH + H+
 Acetyl group attached to coenzyme A to form acetyl coenzyme A (acetyl CoA)
 Fate of pyruvic acid
3. The Krebs cycle
 Also known as citric acid cycle
 Occurs in matrix of mitochondria
 Series of redox reactions
 2 decarboxylation reactions release CO2
 Reduced coenzymes (NADH and FADH2) are the most important outcome
 One molecule of ATP generated by substrate-level phosphorylation
 The Krebs Cycle
4. Electron transport chain
 Series of electron carriers in inner mitochondrial membrane reduced and oxidized
 As electrons pass through chain, exergonic reactions release energy used to form ATP
 ______________________
 Final electron acceptor is oxygen to form _______________________
 Carriers act as proton pumps to expel H+ from mitochondrial matrix
 Creates ______________________________ – concentration gradient and electrical gradient
 Gradient has potential energy – proton motive force
 As H+ flows back into matrix through membrane, generates ATP using ____________________
 The actions of the three proton pumps and ATP synthase in the inner membrane of mitochondria
Summary of cellular respiration
 Glucose anabolism
 Glucose storage: _________________________________
 Polysaccharide that is the only stored carbohydrate in humans
 Insulin stimulates hepatocytes and skeletal muscle cells to synthesize glycogen
 Glucose release: ________________________________
 Glycogen stored in hepatocytes broken down into glucose and release into blood
 Glycogenesis and glycogenolysis
Formation of glucose from proteins and fats: gluconeogenesis

 Glycerol part of triglycerides, lactic acid, and certain amino acids can be converted
by the liver into glucose
 Glucose formed from noncarbohydrate sources
 Stimulated by cortisol and glucagon
Lipid metabolism
 Transport by lipoproteins
 Most lipids nonpolar and hydrophobic
 Made more water-soluble by combining them with proteins to form lipoproteins
 Proteins in outer shell called apoproteins (apo)
 Each has specific functions
 All essentially are transport vehicles
Apoproteins
 Apoproteins categorized and named according to density (ratio of lipids to proteins)
a. Chylomicrons
i. Form in small intestine mucosal epithelial cells
ii. Transport dietary lipids to ______________________
b. Very low-density lipoproteins (VLDLs)
i. Form in hepatocytes
ii. Transport endogenous lipids to __________________
c. _______________________ (LDLs) – “bad” cholesterol
i. Carry 75% of total cholesterol in blood
ii. Deliver to body cells for repair and synthesis
iii. Can deposit cholesterol in fatty plaques
d. ________________________ (HDLs) – “good” cholesterol
i. Remove excess cholesterol from body cells and blood
ii. Deliver to liver for elimination

2 sources of cholesterol in the body
1. Present in foods
2. Synthesized by hepatocytes
As total blood cholesterol increases, risk of coronary artery disease __________________________
 Treated with exercise, diet, and drugs
Lipids can be oxidized to provide_____________
 Stored in ______________ if not needed for ATP
Major function of adipose tissue to remove triglycerides from chylomicrons and VLDLs and store it until
needed
 ______% of all body energy reserves
Lipid catabolism: ____________________________
 Triglycerides split into ___________________ and ___________________
 Must be done for muscle, liver, and adipose tissue to oxidize fatty acids
 Enhanced by epinephrine and norepinephrine
Lipid anabolism:_______________________
 Liver cells and adipose cells synthesize lipids from glucose or amino acids
 Occurs when more calories are consumed than needed for ATP production
 Pathways of lipid metabolism
Protein metabolism
 Amino acids are either oxidized to produce___________ or used to synthesize __________________
 Excess dietary amino acids are not excreted but converted into glucose (gluconeogenesis) or
triglycerides (lipogenesis)
Protein catabolism
 Proteins from worn out cells broken down into amino acids
 Before entering Krebs cycle amino group must be removed – ________________________
 Produces ammonia, liver cells convert to urea, excreted in urine
 Various points at which amino acids enter the Krebs cycle for oxidation
Protein anabolism
 Carried out in ribosomes of almost every cell in the body
 _____ essential amino acids in the human
 Must be present in the diet because they cannot be synthesized
 Complete protein – contains sufficient amounts of all essential amino acids – beef,
fish, poultry, eggs
 Incomplete protein – does not – leafy green vegetables, legumes, grains
 10 other nonessential amino acids can be synthesized by body cells using transamination
Key molecules at metabolic crossroads
3 molecules play pivotal roles in metabolism
Stand at metabolic crossroads – reactions that occur or not depend on nutritional or
activity status of individual
1. __________________________
a. Made shortly after glucose enters body cell
b. 4 fates – synthesis of glycogen, release of glucose into blood stream, synthesis of
nucleic acids, glycolysis
2. __________________________
a. If there is enough oxygen, aerobic cellular respiration occurs
b. If there is not enough oxygen, anaerobic reactions can produce lactic acid, produce
alanine or gluconeogenesis
3. __________________________
a. When ATP is low and oxygen plentiful, most pyruvic acid goes to ATP production via
Acetyl CoA
b. Acetyl CoA os the entry into the Krebs cycle
c. Can also be used for synthesis of certain lipids
Metabolic adaptations
 During the absorptive state ingested nutrients are _________________________________
o Glucose readily available for ATP production
 During postabsorptive state ________________________________________________________________
o Energy needs must be met by fuels in the body
o Nervous system and red blood cells depend on glucose so maintaining steady blood glucose
critical
o Effects of _________________________ dominate
Metabolism during absorptive state
o Soon after a meal nutrients enter blood
 Glucose, amino acids, and triglycerides in chylomicrons
o 2 metabolic hallmarks
1. Oxidation of glucose for ATP production in all body cells
2. Storage of excess fuel molecules in hepatocytes, adipocytes, and skeletal muscle
cells
o Pancreatic beta cells release insulin
 Promotes entry of glucose and amino acids into cells
 Principal metabolic pathways during the absorptive state
Metabolism during postabsorptive state
 About 4 hours after the last meal absorption in small intestine nearly complete
 Blood glucose levels start to __________________
 Main metabolic challenge to maintain normal blood glucose levels
 ___________________________
 Breakdown of liver glycogen, lipolysis, gluconeogenesis using lactic acid and/or
amino acids
 __________________________
 Oxidation of fatty acids, lactic acid, amino acids, ketone bodies and breakdown of
muscle glycogen
 Principal metabolic pathways during the postabsorptive state
Hormones and autonomic nervous system regulate metabolism during postabsorptive state
 As blood glucose decline, insulin secretion falls
 Glucagon – increases release of glucose into blood via gluconeogenesis and
glycogenolysis
 Sympathetic nerve endings of ANS release norepinephrine and adrenal medulla releases
epinephrine and norepinephrine
 Stimulate lipolysis, glycogen breakdown
Heat and energy balance
 Heat – form of energy that can be measured as temperature and can be expressed in calories
 calorie (cal) – amount of heat required to raise 1 gram of water 1°C
 Kilocalorie (kcal) or Calorie (Cal) is 1000 calories
 Metabolic rate – overall rate at which metabolic reactions use energy
 Some energy used to make ATP, some lost as heat
 Basal metabolic rate (BMR) – measurement with body in quiet, resting, fasting condition
 Body temperature homeostasis
 Despite wide fluctuations in environmental temperatures, homeostatic mechanisms
maintain normal range for internal body temperature
 Core temperature (37°C or 98.6°F) versus shell temperature (1-6°C lower)
 Heat produced by exercise, some hormones, sympathetic nervous system, fever, ingestion
of food, younger age, etc.
Heat can be lost through
 Conduction to solid materials in contact with body
 Convection – transfer of heat by movement of a gas or liquid
 Radiation – transfer of heat in form of infrared rays
 Evaporation exhaled air and skin surface (insensible water loss)
 Hypothalamic thermostat in preoptic area
 Heat-losing center and heat-promoting center
Thermoregulation
 If core temperature declines
 Skin blood vessels constrict
 Release of thyroid hormones, epinephrine and norepinephrine increases cellular
metabolism
 Shivering
 If core body temperature too high
 Dilation of skin blood vessels
 Decrease metabolic rate
 Stimulate sweat glands
Ch 25 (cont) Nutrition
Nutrients are chemical substances in food that body cells use for growth, maintenance, and repair
6 main types
1.______________________– needed in largest amount
2.______________________
3.______________________
4.______________________
5.______________________
6.______________________
Essential nutrients must be obtained from the diet
Guidelines for healthy eating
Basic guidelines
 Eat a variety of foods
 Maintain a healthy weight
 Choose foods low in fat, saturated fat and cholesterol
 Eat plenty of vegetables, fruits and grain products
 Use sugars in moderation only
-Inorganic elements that occur naturally in Earth’s crust
-Eat foods that contain enough calcium, phosphorus, iron and iodine
-Excess amounts of most minerals are excreted in urine and feces
-Major role of minerals to help regulate enzymatic reactions
Vitamins
Organic nutrients required in small amounts to maintain growth and normal metabolism
Do not provide energy or serve as body’s building materials
Most are ______________________________
Most cannot be synthesized by the body
Vitamin K produced by bacteria in GI tract
No single food contains all the required vitamins
2 groups
 Fat-soluble – ______,_______,_______,_______
 Water-soluble – several B vitamins and vitamin C
End of Chapter 25