METABOLISME ENERGI DAN ZAT GIZI MAKRO PERTEMUAN 9 HENDRA WIJAYA-DUDUNG ANGKASA PROGRAM STUDI ILMU GIZI-FIKES

VISI DAN MISI UNIVERSITAS ESA UNGGUL

KEMAMPUAN AKHIR YANG DIHARAPKAN Mahasiswa mampu menjelaskan pengertian protein, proses pencernaan, penyerapan dan sirkulasi protein

Protein bag. Dr sel hidup, bag. Terbesar sth air. Sbg besar ada di otot, tlng rawan, tulang, kulit , jaringan lain, cairan tubuh Ptn; molekul makro; terdiri dari rantai a. amino yang terikat dalam ikatan peptida. Asam amino : unsur karbon, hidrogen, oksigen dan nitrogen, disamping itu ada unsur fosfor, besi, sodium, dan kobalt. Unsur nitrogen a/ unsur utama ptn, 16% dari berat ptn. Ptn dihidrolisa  20-24 asam amino. Ada 3 cara : hidrolisa asam, alkal, enzimatik.

Asam amino Asam amino alifatik (satu karboksil, satu amino) ; glisin, alanin, serin, threonin, valin, leucin, isoleucin. Asam amino aromatik : penilalanin, tyrosin Asam amino belerang : sistin, methionin Asam amino heterosiklik : tryptophan, prolin, hydroxyprolin,3-hydoxiprolin Asam amino basik (satu karboksil, dua amino; histidi, arginin, lisisn. Hidroxilisin, citrulin Asam amino asidik(satu amino, dua karboksil) ; asam aspartat, asam glutamat

Proteins Dietary sources Animal proteins contain greatest amounts of essential amino acids- eggs, milk, fish, meats Beans, nuts, and cereals lack some essential amino acids Daily intake- 0.8 g per kg body weight Uses Structural proteins: keratin, collagen, elastin, muscle proteins Functional proteins: enzymes, some hormones

Klasifikasi protein Komponen yg menyusun ptn: ptn sederhana, ptn komplek (hb, lipoprotrin), ptn derivat (albumosa, pepton dsb). Sumber : ptn hewani & nabati Fungsi fisiologinya : sempurna (pemeliharaan & pertumbuhan), setengah sempurna (pemeliharaan), tidak sempurna

Keseimbangan Protein

Sumber ptn Daging (l8.8. hati 19,7, ikan l7, udang segar 21, ayam l8,2, telur 12,8 susu sapi 3,2 , Kacng kedelai 34,9, kac. Hijau 22,3, kac.tanah 25,3, singkong 1,1, jagung 9,2, terigu 8,9, jampang 6,2, kelapa 3,4, daun singkong 6.8

Protein Catabolism Liver cells convert amino acids into substances that can enter the Krebs cycle to produce ATP First deamination removes the amino group (NH2) converts amino groups to ammonia (NH3) & then urea urea is excreted in the urine In liver cells amino acids can also be converted into: Glucose ( gluconeogenesis) fatty acids ( lipogenesis) ketone bodies ( ketogenesis)

Protein Anabolism Involves the formation of peptide bonds between amino acids to produce new proteins. Structural proteins: keratin, collagen, elastin, muscle proteins Functional proteins: enzymes, hemoglobin, antibodies, some hormones Stimulated by human growth hormone, testosterone, thyroxine, and insulin. Protein synthesis carried out on the ribosomes of almost every cell in the body, directed by the cells DNA and RNA.

Regulation of Food Intake Nuclei in the hypothalamus regulate hunger & satiety The brain receives signals from: Neural signals from the digestive tract ( via vagus nerve) Rising blood levels of glucose, amino acids, fatty acids indicate fullness Hormones Insulin & leptin (released from fat cells) suppress hunger glucagon stimulates hunger To a lesser extent, body temperature (increase inhibits eating) and psychological factors

Penyerapan dan Pencernaan Protein

Metabolisme Asam Amino

Intestinal Absorption and Amino Acid Transport After digestion, the resulting amino acids and peptides (di and tri) are efficiently absorbed by enterocytes Occurs along the entire small intestine Most proximal (upper) small intestine Absorption requires carriers (active transport) to bring the amino acid across the brush border membrane, but some passive absorption occurs Active transport is important when lumen amino acid levels are low

Amino Acid Transport Systems These carrier systems traditionally been designated using a lettering system Upper case for sodium-dependence Lower case for sodium-independence (more passive transport) Some exceptions (eg. System L, does not require Na+)

Competition between transporter systems The affinity (Km) of a carrier is influenced both by the hydrocarbon mass of the side chain of the amino acid and by the net electrical charge Branch chain amino acids absorbed faster than smaller amino acids Neutral amino acids absorbed faster than basic or acidic amino acids Essential absorbed faster than non-essential

Amino Acid Transport System Sodium Required Amino Acids Carried L No Leucine, other neutral B Yes Phenylalanine, tyrosine, tryptophan, isoleucine, leucine, valine IMINO Proline, glycine y+ Basic X-AG Aspartate, glutamate B0,+ Most neutral and basic b0,+ Basic and neutral y+L No/Yes ASC Alanine, serine, cysteine t Tryptophan, phenylalanine, tyrosine asc N Glutamine, asparagine, histidine ag

Sodium Coupled Amino Acid Transport Sodium binds to the amino acids transporter Binding increases carrier affinity for amino acids which bind to the carrier

Sodium Coupled Amino Acid Transport Co-transporter forms Carrier complex conformation changes and the sodium/ amino acids enters the cytosol Sodium is pumped out of the cell by a Na+, K+- ATPase

Peptide Absorption (ie. PEPT1) Peptides are coupled to H+ and transported into the intestinal cell H+ pumped back into the intestinal lumen in exchange for Na+ Na+, K+ ATPase pumps Na+ out of the cell in exchange for K+ across the basolateral membrane Gropper et al 2008

Intestinal Basolateral Membrane Transport of Amino Acids Amino acids use similar transporters to cross the basolateral membrane and into the interstitial fluid Free amino acids only Many amino acids absorbed into enterocytes are not transported out

Intestinal Basolateral Membrane Transport of Amino Acids Amino Acid Transport System Sodium Required Amino Acids Carried L No Leucine, other neutral y+ Basic X-AG Yes Aspartate, glutamate b0,+ Basic and neutral A No/Yes Alanine, neutral, short chain, polar ASC Alanine, serine, cysteine, other 3-4 carbon amino acids t Tryptophan, phenylalanine, tyrosine GLY Glycine asc Alanine, serine, cysteine

Protein Metabolism in the Enterocyte Many amino acids absorbed following protein digestion are used by the intestinal cells for energy or protein synthesis Structural proteins Nucleotides Apoproteins New digestive enzymes Hormones

Amino acids may be partially metabolized to other amino acids or compounds, that may be released into portal blood Intestines use 30-40% and internal organs use up to 50% of the essential amino acids absorbed from the diet 90% of glutamate absorbed is thought to be used by the intestines

Intestinal Metabolism- Glutamine Glutamine not used for energy, may be partially catabolized to generate ammonia and glutamate Ammonia enters the portal blood for liver uptake or may be used by the intestine for carbamoyl phosphate synthesis Glutamate may undergo transamination (removal on amino group) to form alpha-ketoglutarate Intermediate in the Tricarboxylic acid (TCA) cycle Amino group is transferred to pyruvate to form alanine  portal blood and to the liver

Penyakit  ptn 2 jenis peny. Gizi  berdasarkan defisiensi dan kelaiann sintesa /metabolisme Kelebihan  obesitas, memberatkan organ hati & ginjal Kelbeihan  asidosis, dehidrasi, diare, kenaikan amoniak, ureum darah dan demam. Batas dua kali KGA

Marasmik-Kwashiorkor Gambaran klinik merupakan campuran dari beberapa gejala klinik kwasiorkor dan marasmus, dengan BB/U < 60 % baku median WHO_NCHS disertai oedema yang tidak mencolok

Gambaran Klinis marasmus

Kwashiorkor Dominan kekurangan protein Oedema Ketidakseimbangan elektrolit akibat melemahnya pompa Na/K Na di dalam sel meningkat K dalam sel keluar masuk ke dalam aliran darah dan di ekskresikan Oedema Timbul pada usia 1-3 tahun Pertumbuhan terhambat Moon face, apatis

Akar Masalah Dampak Kurang Gizi Penyebab lsg Mak. Tdk seimbang Penyakit infeksi Penyebab tdk langsung Tdk persediaan pangan Pola Asus tdk memadai Sanitasi dan airbersih/Pelay.Kes. Dsr tdk memadai Kurang Pendidikan,Pengetahuan dan ketrampilan Pokok masalah di masyarakat Kurang pemberdayaan Wanita dan keluarga,kurang pemanfaatan Sumberdaya masyarakat Pengangguran,inflasi,kurang pangan dan kemiskinan Akar Masalah ( Nasional) Krisis Ekonomi, Politik dan sosial Sumber: Unicef

Ketidakseimbangan Elektrolit Intracellular In blood stream Na K K Na

Gambaran Klinis kwashiorkor

Prevalensi KEP Balita (2002) (Berdasarkan indeks BB/U) Gizi Lebih 2.2% Gizi Baik (normal) 70.5% Gizi Kurang 19.3% Gizi Buruk 8.0%

Fungsi protein : Pertumbuhan dan pemeliharaan Pembentuk ikatan2 essensial tubuh (hormon, enzim) Mengatur keseimbangan cairan Memelihara netralitas tubuh Pembentukan antibodi Mengangkut zat2 gizi Sumber energi

Angka kecukupa protein Dewasa 0,75 gram/kh BB Remaja : 0,9 s/d 2 gram /kh BB balita 1-1,5 gram /kg BB Ibu hamil + 12 gram Ibu sui + 16 gram s/d 11 gram tergantung