Food Animal Growth and Development Test 3

In the US about __ of people are overweight or obese

3/4

how many deaths are from obesity

1.9 million global CVD deaths

how many CVD deaths worldwide

1/10

above BMI 24, what point increase raises mortality

every 5 point increases raises mortality risk by >30% severe obesity by 300%

what is obesity linked to

65-78% of primary hypertension cases

what countries are the most obese

mexico, USA, finland

what countries do not have as much obesity

korea and japan

what percent of dogs in the US are obese

22%

what percent of cats are obese

33%

what percent of pets are obese

59%

over the past 10 years, there has been a ___ increase in the number of overweight cats and and a _ increase in the number of overweight dogs

169%, 158%

what kind of pets are over twice as likely to be obese

neutered

obese pets live ___ shorter on average than their non-obese counterparts

2.5 years shorter

what is the structure of adipose tissue

• specialized connective tissue (loose)

• organized into lobules by dense connective tissue called septa

what are the principal cells called in adipose tissue

fat cells - adipocytes

what do septa contain

blood vessels and nerves to adipose tissue

what is the mitochondrial density of brown adipocytes

High (UCP-1+)

what is the LD morphology of brown adipocytes

multi-locular

what is the mitochondrial density of white adipocyte

low

what is the LD morphology of white adipocyte

Uni-locular

what is beige adipocyte mitochondrial density

medium (UCP-1+)

what is the LD morphology of beige adipocytes

multi-locular

what is brown adipose tissue characterized by

• good adipose tissue

• high vascularity

• dense sympathetic innervation

• BAT

what is white adipose tissue characterized by

• bad adipose tissue

• low vascularity

• sparse sympathetic innervation

• WAT

what is beige adipose tissue characterized by

• good adipose tissue

• intermediate vascularity

• convertible sympathetic innervation

• BgAT

where is BAT located

• limited to some locations

• common in neonates, hibernating and cold adapted animals

where is BgAT located

• limited to some locations

• cervical and supraclavicular

where is WAT located

• broadly distributed in the body

• grouped by the relation to other tissues or organs

• the development in order is: visceral → subcutaneous → intermuscular → intramuscular

is WAT distribution different across species

yes

where is WAT in pigs

under hide/backfat in pigs

what animal has the most WAT subcutaneously

pork

what animal has the most WAT intermuscularly

beef

what animal has the most fat intramuscularly

beef

what is intermuscular fat

fat between muscles, closely associated with epimysium

what is intramuscular fat

fat within muscle, specially associated with perimysium

what is the function of adipose tissue

• storage of energy and vitamins that are fat soluble

• protection of vital organs

• physical support and insulation

• source of hormones

• generation of heat (BAT and BgAT) - nonshivering thermogenesis

what is the energy density of fat

9 calories per gram

what are the stem cells for adipose tissue

they come from multipotent, proliferative mesenchymal cells

the mesoderm forms the trunk the neural crest forms the craniofacial

what are the parts of adipogenesis

adipoblasts, pre-adipocytes, adipocytes

what are characteristics of adipoblasts

• committed to the adipocyte lineage

• proliferative

• contain no obvious lipid droplets

what are characteristics of pre-adipocytes

• determined to become fat cells

• proliferative

• contain multiple small lipid droplets

what are characteristics of adipocytes in adipogenesis

• terminally differentiated

• non-proliferative

• increased lipogenic enzyme activity with accumulation of a large single droplet of lipid

• hypertrophy of adipocyte without hyperplasia leads to fat deposition

what kind of control is adipocyte differentiation under

molecular/genetic control

how many genes contribute to determining body weight and fat deposition

over 6,000 genes

how many differentially expressed genes have been identified in the differentiating adipocytes, with 1,116-1249 genes specific to particular fat depots

over 2300

how many genes are associated with adipocyte phenotype acquisition

over 2000 genes among with preadipocyte factor 1 which is regarded as a gatekeeper of adipogenesis

when does hyperplasia happen

prenatal and postnatal

when does hypertrophy occur

only prenatally

what are external growth stimuli

MSCs, adipoblasts, preadipocytes

what is adipogenesis under control by

molecular control

what are factors influencing adipogenesis

• adipokines

• hormonal factors

• receptors and transcription

• diet effects

• enzymes and transporters

• age and weight effects

how do adipokines affect adipogenesis

n>600, proteins secreted by adipose tissue that have metabolic and adipogenic effects on distant adipose cells or tissue

how does insulin affect adipogenesis

• important factor for both adipocytes and lipogenesis

• insulin receptor is required for adipocyte differentiation

• promotes lipogenesis by upregulating GLUT4 expression

how do receptors and transcription affect adipogenesis

a master regulator: peroxisome proliferator-activated receptor gamma (PPARgamma)

how do diet effect adipogenesis

• sufficient energy in the diet causes adipocyte hypertrophy and hyperplasia

• dependent on stage of animal development but feeding high planes of nutrition prior to slaughter increases marbling

• dietary protein: energy ratios are important

• diets with amino acids deficiencies will often result in increased lipogenesis, muscle growth cannot be maximized without AA balance

how do age and weight affect adipogenesis

• as animals age, they fatten and adipocytes swell with fat and recruitment of smaller adipocytes → bimodal distribution

• loss of weight keeps the same number of adipocytes, and the adipocytes shrink in size and next weight gain is even larger due to existing population

what is the chemical composition of adipose tissue

• lipid = 76-94%

• water = 5-20%

• protein = 1-4%

what are the two categories of triglycerides

glycerol and fatty acids

what are the two categories of fatty acids

saturated and unsaturated

what is the animal with the most abundant unsaturated fatty acids

chicken

what is the most abundant saturated fatty acid in animals

palmitic acid

what is the most abundant unsaturated fatty acid in animals

oleic acid

what is cellularity

cellularity of tissue is the state of having cells, measured as the number of its constituent cells in a certain amount of time

cellularity is affected by what

type of cellular growth

what happens to cellularity as age increases

it also increases

what does intramuscular adipocyte count for

nearly half the total number of adipocytes in the body of pigs, but only 10% of total lipid in the body

what are two parts of lipid metabolism

lipogenesis and lipolysis

what is lipogenesis

a process involved in absorption of nutrients from blood and subsequent synthesis and esterification to form triglycerides in adipocyte

what is lipolysis

hydrolysis of triglyceride TG to free fatty acids and glycerol

what is net lipid accretion

lipogenesis - lipolysis

where does lipogenesis occur

its location is species dependent

• in cattle, sheep, and pigs it occurs in adipose tissue

• in avian it occurs in the liver

what are two sources of fatty acids

dietary fat and de novo synthesis of fatty acids and formation of TG in adipocytew

what is the principal substrate of de novo synthesis of fatty acids

It is species-dependent

• in non-ruminants: glucose

• ruminants: acetate from rumen metabolism

what is lipolysis controlled by

two major lipases

1. hormone sensitive lipase (HSL within adipocytes)

2. lipoprotein lipase (LPL, attached to capillary endothelial cells)

what is lipolysis primarily stimulated by

hormones with catabolic actions

what are 4 things that affect the regulation of composition and metabolism of adipose tissue

1. genetics

2. species

3. gender

4. hormone - leptin

true or false: any factors that affect adipogenesis will affect adipose tissue composition

true

true or false: any factors that affect lipid metabolism will affect adipose tissue composition

true

how does genetics affect tissue composition

• fatter genotypes possess a higher percentage of lipid in backfat than leaner genotypes

• breeds with increased reproductive rates and milk production show increased visceral fat

how does species differences affect tissue composition

• differences in adipose composition due to differences in lipid metabolism eg ruminants vs monogastrics

• growth rates differ between species, which influences adipocyte size and number along with adipocyte metabolism and composition

how can gender affect tissue composition

steroids (eg estrogen and testosterone) affect lipid metabolism and distribution of fat among depots

can white fat turn into beige/brown fat

yes white fat can transform into beige fat through things such as cold exposure, exercise, diet compounds, and hormones. this leads to increased fat burning and heat production

what is cartilage

a type of connective tissue

what is cartilage composed of

cells called chondrocytes (cartilage producing cells) that are located in small cavities called lacunae

what do chondrocytes make

a highly specialized matrix - firm but pliable (rubbery)

most cartilage is surrounded by what

perichondrium

what are characteristics of the perichondrium

• a membrane of fibrous (dense) connective tissue around surface of cartilage

• articular cartilages do not have perichondrium

• has two layers: 1 - fibrous (outer), 2 - condrogenic (inner)

does cartilage have direct vascular supply

no direct vascular supply (no blood vessels)

how do nutrients get to cartilage

diffuse through matrix to nourish chondrocytes

what is this

hyaline cartilage

what is this

fibrocartilage

what is this

elastic cartilage

what is the location of hyaline cartilage

fetal bones, articular surface, trachea

what is the location of fibrocartilage

intervertebral disc, menisci

what is location of elastic cartilage

ear, nose, epiglottis

what is the ECM of hyaline cartilage like

type II collagen aggrecan, tough and somewhat flexible

what is the ECM of fibrocartilage like

type II collagen, little ground substance, extremely tough

what is the ECM of elastic cartilage

type I and II collagen aggrecan, elastic fibers

does hyaline cartilage of perichondrium

yes, except articular surface

does fibrocartilage have perichondrium

no