scit 1408 applied human anatomy and physiology ii - nutrition, metabolism chapter 24 b

8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Nutrition, Metabolism Chapter 24 B

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Synthesis of Proteins

Amino acids are the most important anabolic

nutrients, and they form:

All protein structures

Most functional molecules- ENZYMES


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Synthesis of Proteins

Synthesis controlled by:

Hormones

Availability of A !" different amino acids

#aries $ith a%e


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Summary: Carbohydrate Metabolic Reactions

Table 24.4.1


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Summary: Lipid and Protein Metabolic

Reactions

Table 24.4.2


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Carbohydrate!at and "mino "cid Pools

!i#ure 24.1$


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%ntercon&ersion Path'ays of (utrients

!i#ure 24.1)


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"bsoprti&e and Postabsorpti&e States

Absorptive

&urin%, 'ust after nutrient inta(e

)ostabsorptive

*+ tract is empty

Ener%y sources from brea(do$n of body reserves

Metabolic controls eualie blood concentrationsof nutrients bet$een t$o states



"bsoprti&e State

Mostly anabolic

Amino acids to proteins. muscle, liver

*lycerol / 0A to tri%lycerides

*lucose to %lyco%en. muscle, liver

*lucose, 0A to fat. adipose

&ietary %lucose is ma'or ener%y fuel

E1cess amino acids are deaminated and used for

ener%y or stored as fat in the liver



"bsoprti&e State

!i#ure 24.1*a



Principal Path'ays of the "bsorpti&e State

!i#ure 24.1*b



%nsulin +ffects on Metabolism

!i#ure 24.1,



-iabetes Mellitus

0rom 2 insulin or abnormal insulin receptors

2 *lucose upta(e by cells

Metabolic acidosis 3%lycolysis to lactic acid4

protein $astin%- $ei%ht loss result as fats andtissue proteins are used for ener%y

5starvation in midst of hi%h %lucose6


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Postabsorpti&e State

!i#ure 24.2a

Glucose

feeds

CNS


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Principle Path'ays in the Postabsorpti&e

State

!i#ure 24.2b


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%nfluence of /luca#on

!i#ure 24.21

SNS epinephrine


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Li&er Metabolism

0unctions

)ac(a%es fatty acids to be stored and transported

Synthesies plasma proteins

Synthesies nonessential amino acids

&eaminates ammonia to urea

Stores %lyco%en. helps re%ulate 7blood %lucose8

Synthesies9stores vitamins, stores iron, de%rades

hormones, deto1ifies


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Cholesterol

asis of bile salts, steroid hormones,vitamin &

Ma(es up part of the hedgehog molecule that

directs embryonic development

;ravels in lipoproteins


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Cholesterol

ipoproteins are classified as:

H&s < hi%h-density lipoproteins have more

protein content

&s < lo$-density lipoproteins have a

considerable cholesterol component

#&s < very lo$ density lipoproteins are mostly

tri%lycerides


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Plasma Cholesterol Le&els

;he liver produces cholesterol:

At a basal / constant level

#ia a ne%ative feedbac( loop involvin% serum

cholesterol levels

+n response to saturated fatty acids


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Plasma Cholesterol Le&els

=nsaturated fatty acids > cholesterol e1cretion

Saturated fatty acids 2 e1cretion

ome%a-? fatty acids 2 saturated fats / cholesterol


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(on0-ietary !actors "ffectin# Cholesterol

> &:

Stress

Smo(in%

caffeine

> H&:

Aerobic e1ercise

ody shape / cholesterol levels

0at in upper body correlated > cholesterol

0at on hips, thi%hs correlated 2 cholesterol


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!eedin# eha&iors

@ Neural si%nals from the di%estive tract

! loodborne si%nals related to ener%y stores

? Hormones

B ody temperature

C )sycholo%ical factors


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(utrient Si#nals Related to +ner#y Stores

2 eatin% from > levels of:

*lucose

Amino acids

0atty acids

eptin


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ormones3 Temperature3 Psycholo#ical

!actors

> hunger: *luca%on

Epinephrine

< hunger:

+nsulin

Dholecysto(inin

+ncreased body temperature

)sycholo%ical factors that have little to do $ith caloric

balance can also influence eatin% behaviors


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ypothalamic Command of "ppetite

!i#ure 24.25


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Metabolic Rate

ate of ener%y output 3e1pressed per hour4 eual to

the total heat produced by:

All the chemical reactions in the body

;he mechanical $or( of the body Measured directly $ith a calorimeter or indirectly

$ith a respirometer


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Metabolic Rate

asal metabolic rate 3M4

eflects the ener%y the body needs to perform its

most essential activities

;otal metabolic rate 3;M4 ;otal rate of (ilocalorie consumption to fuel all

on%oin% activities


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!actors that %nfluence MR

Surface area, a%e, %ender, stress, and hormones

As the ratio of surface area to volume increases,

BMR increases

Males have a disproportionately hi%h M Stress increases M

;hyro1ine increases o1y%en consumption, cellular

respiration, and M


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Re#ulation of ody Temperature

ody temperature < balance bet$een heat

production and heat loss

At rest, the liver, heart, brain, and endocrine or%ans

account for most heat production

&urin% vi%orous e1ercise, heat production from

s(eletal muscles can increase ?"


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Normal body temperature is ?F!°D 3G!°04.

optimal enyme activity occurs at this temperature

;emperature spi(es above this ran%e denature

proteins and depress neurons


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!i#ure 24.24


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Core and Shell Temperature

Dore or%ans have > est temp.

Dore I in s(ull, thoracic, abdominal cavities

;emp pretty constant here

Shell or%ans have 2 est temperature. Shell I s(in

;emp varies here. 3!"°D


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Mechanisms of eat +6chan#e

0our mechanisms:

@ adiation < loss of heat in the form of infrared rays

! Donduction < transfer of heat by direct contact

? Donvection < transfer of heat to the surroundin% air

B Evaporation < from evaporation of $ater.

0rom the lun%s, mouth mucosa, s(in

;hese are insensible heat losses 3unnoticeable4

Evaporative heat loss becomes sensible 3noticeable4 $hen

body temperature rises and s$eatin% produces increased

$ater for vaporiation


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Thermore#ulation0 ypothalmus

Dold

#asoconstriction of

cutaneous blood vessels

> metabolic rate

Shiverin%

> thyro1ine release

Hot

#asodilation - cutaneous

S$eatin%


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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings !i#ure 24.2$

"cti&atesheat0losscenter inhypothalamus

lood 'armer

than hypothalamic

set point

S'eat #lands acti&ated:

secrete perspiration3 'hich

is &apori7ed by body heat3

helpin# to cool the body

S8in blood &essels

dilate: capillaries

become flushed 'ith

'arm blood9 heat

radiates from

s8in surface

ody temper0ature decreases:blood temperaturedeclines and hypo0thalamus heat0loss center shuts off;

Stimulus:%ncreased bodytemperature


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yperthermia0 heat stro8e

Environment too hot

Heat loss processes not enou%h

Elevated body temperatures depress the

hypothalamus )ositive-feedbac( mechanism increases body

temperature and metabolic rate

0atal if not corrected

JJMali%nant hyperthermia


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eat +6haustion

Heat-associated collapse from vi%orous e1ercise

> body temperature, confusion, faintin%

&ue to dehydration / lo$ blood pressure

Heat-loss mechanisms fully functional Dan pro%ress to heat stro(e if the body is not

cooled and rehydrated


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!e&er 0 Controlled hyperthermia

0rom infection, cancer, aller%ic reactions, central

nervous system in'uries

)yro%ens cause release of prosta%landins

)rosta%landins reset the hypothalamic thermostat ;he hi%her set point is maintained until the natural

body defenses reverse the disease process


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-e&elopmental "spects

*ood nutrition is essential in utero as $ell as

throu%hout life

ac( of proteins needed for fetal %ro$th and in the

first three years of life can lead to mental deficits

and learnin% disorders

Kith the e1ception of insulin-dependent diabetes

mellitus, children free of %enetic disorders rarely

e1hibit metabolic problems

+n later years, non-insulin-dependent diabetes

mellitus becomes a ma'or problem


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-e&elopmental "spects

Many a%ents prescribed for a%e-related medical

problems influence nutrition

&iuretics can cause hypo(alemia 3potassium loss4

Antibiotics can interfere $ith food absorption

Mineral oil interferes $ith absorption of fat-soluble

vitamins

E1cessive alcohol consumption leads tomalabsorption problems, certain vitamin and

mineral deficiencies, deran%ed metabolism, and

dama%e to the liver and pancreas

scit 1408 applied human anatomy and physiology ii - nutrition, metabolism chapter 24 b

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