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Human Bio 2: Digestion/Blood

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Digestive System
brings nutrients into the body and sends them into the blood
Complex Carbs, Fats and Proteins
broken down into simple sugars, amino acids, and glycerol + fatty acids, this is what our body is built of
Alimentary Canal
-separate tube (system)
-"outside" the body
-coated by a special substance, so the tube is not digested
Physical Digestion
chewing (incisors, molars), herbivores cut and grind
-mixing and mashing with digestive juices
(cooking already breaks food down)
Chemical
hydrolysis to break up the macromolecules, do this by using acids
-digestive enzymes: absorb macromolecules into the blood through:
-simple diffusion
-active transport
-facilitated diffusion
1) Mouth
teeth: breaks up
salivary glands: salivary amylase breaks down carbs (into simple sugars)
tongue: mixes and mashes (taste senses: salt, sour, sweet, bitter, umami
(peristalsis moves food down throat to stomach
2) Stomach
stomach folds, unfolds as you fill up your stomach
-chamber
-sensors: when the stomach expands, sensors tell the stomach to start the digestive process
-releases acids into the stomach
-pepsin: digests proteins, muscles of the stomach begin to mix and mash
-lower esophageal sphincter--> heart burn=acid eats the esophagus from eating too much (GERD: esophageal cancer, cells have to rebuild everyday)
-mucus
-Chyme is dumped into the small intestine
3) Small Intestine
-finishes the digestion of proteins
-digests lipids
-pancreas= releases digestive enzymes (CCK, Secretin) and bicarbonate (buffer: neutralizes the acid in the SI)
Cystic Fibrosis
excess mucus production, blocks the flow of enzymes: not enough nutrients (fibrous coat around the pancreas holes)
Ulcer
wound of the stomach lining (from acids)
Hypothalamus
control center of digestion (controls hunger)
4) Large Intestine
storage, elimination, water absorption, adipose cells store fat, leads to obesity
Leptin
hormone that stops hunger (protein), can't take it as a pill because it will be digested- must be injected
-lacks a receptor= continues to store away
Functions of Blood
transport of:
-nutrients
-metabolites
-excretory products
-gasses
-hormones (chemicals dumped into the blood by glands)
-cells
-heat

transmission of force (blood pressure), ex. kidney filters waste

coagulation (convert itself into a cell)

"milieu interieur"
Urea
biproduct of amino acids
Metabolites
toxins--> built up in blood
Red Blood Cell
carries oxygen

Hematocrit: blood volume of RBC (45% males, 40% females)
White Blood Cell
produced in bone marrow, transported to injuries to prevent bacterial infection "defense cells"
Blood Components
Red Layer: cells, platelets (250,000-300,000), red blood cells (4,800,000-5,400,000)

White Layer:
-proteins in plasma 7-8% (albumen-osmotic, globulins, coagulation)
-water 91-92%
-Ions, sugars, lipids 1-2%

-Don't want cells to burst, water the water concentration
White Blood Cells
-Neutrophils (phagocytosis during inflammation)
-Lymphocytes (immune responses)
-Monocytes (phagocytosis in defense)
-Essinocytes (parasitic worms)
-Basophils (more specific, secrete substances for inflammatory responses and fat removal from blood)
Regulation of 02 Carrying Capacity in Blood
-Hemoglobin can carry 4 oxygens (heme)
-250,000,000 hemoglobin molecules in one RBC
-Kidney regulates RBC levels, releases Erythropoietin to induce greater RBC levels production by bone marrow (sensor and control system)
Sickle Cell Anemia
-genetic
-form globules that stretch the RBC, becomes wider than the blood vessel and gets stuck
-Malaria: in RBC, parasites that uses hemoglobin as a food source
Formation of Blood Cells
stem cells in bone marrow, can become any cells (RBC, lymphocyte, monocyte, etc)
Blood Cell Types
A: antigen-A , Antibody-B, Safe to transfer from A, AB to A, 0
B: Antigen-B, Antibody-A, Safe to transfer from B, AB to B, 0
AB: Antigen A+B, no antibody, safe to transfer from AB to A, B, AB, 0)
O: Antibody=A +B, safe to transfer from A, B, AB, O to O
Antibodies
Attack blood cells, coagulate, harden, die (type A person needs a transfusion from another type A)
-different blood groups in U.S
Rh Factor
Dad Rh+ and Mom Rh-
-->infant= possibility of Rh+
--> leaks into mother system, mothers body attacks, infant is ok though
-->pregnant again, is at risk, attacks the fetus
Special Property of Blood
Homeostasis: prevention of blood loss maintained by a 3 stage mechanism which leads to blood clot formation
1) Injury to blood vessel
2) Wall of vessel contracts
3) Platelets stick to collagen fibers of damaged vessel wall
4) More permanent clot forms
The Food Requirement
A) As a fuel- to burn for energy
B) As building blocks for maintenance or replacement for growth and reproduction
Food Components/Uses
1) Carbohydrates= energy source, minor structure
2) Fats=energy, membrane component
3) Proteins= Building Component-Structures and enzymes secondary use for energy
4) Nucleic acids= genetic building blocks
5) Vitamins= cofactors for metabolic regulation
6) Minerals & trace elements= Inorganic Structural component, metabolic assistance
7) Water= medium of life
Gastrointestinal System Requirements /Regions
A) Food Collection/Capture Method
Region- external and mouth
B) Breakdown Methods (digestion)
1) Physical grinding/chewing, mixing/mashing, solubilization/denaturization
2) Chemical - Process of hydrolysis General - acid H+ Specialized - enzymes for each component Region- early gastrointestinal tract; mouth, stomach, beginning of small intestine
Note: the body must be protected from self-digestion C) Uptake Methods (absorption)
1) concentration and simple diffusion
2) Facilitated diffusion
3) Active transport Region- lower portion of the small intestine
Note: requires large surface (intestinal villi) and a whole body distribution system (blood)
D) Elimination of undigested material Region- large intestine
Accessory Glands
1) Salivary Glands
Secretion of moisture and carbohydrate digestive enzymes
2) Liver and Gall Bladder Synthesis, storage and secretion of bile salts for lipid digestion/ absorption
Secondary function: waste removal by liver
Note: Liver buffers the concentration of nutrients in the blood after intestinal absorption
3) Pancreas Secretion of bicarbonate (neutralizes acid) Secretion of multiple digestive enzymes
Digestion and Absorption of Specific Foodstuffs (carbs)
1) Digestion Start- Salivary Amylase in mouth Major- Pancreatic Amylase in Small Intestine Completion-disaccharidases on intestinal cells
2) Absorption Active transport and facilitated diffusion into cells, followed by simple diffusion into blood
Digestion and Absorption of Specific Foodstuffs (proteins)
1) Digestion
Phase I - endopeptidases in stomach and Small intestine
Phase II- ectopeptidases in Small intestine
Phase III- di, tri, tetrapeptidases on intestinal cells

2) Absorption Active transport- distinct systems for different Amino Acid types, into cells then Simple diffusion into blood
Digestion and Absorption of Specific Foodstuffs (fats)
1) Digestion
"Emulsification" by bile salts Hydrolysis by lipases in small intestine
2) Absorption Hydrophobic diffusion of lipid/bile micelle through membrane Coated with protein, transported through lymphatics to blood
Gastric Events
1) Stomach distension augments gastric fluid secretion
2) Peptides stimulate Gastrin (hormone) production 3) Gastrin greatly increases stomach acid and pepsin (enzyme) secretion
4) High acid content begins shut-down of the process
Duodenal (intestinal) events
1) Entrance (from stomach) of acid, amino acids and fats
initiates production of intestinal hormones
[Secretin, cholecystokinin (CCK), gastric inhibitory peptide (GIP)]
2) Secretin and CCK stimulate digestive juice secretion 3) GIP feeds back to shut down stomach secretions as digestion is completed
4) CCK feeds back to brain to indicate satiation
Coagulation
conversion of portions of the blood from a fluid to a solid state, helps to preserve Hemostasis (maintenance of blood volume) in the face of injury to a blood vessel. This prevention of blood loss occurs in three phases or levels:
A) Blood Vessel spasm (closing).
B) Platelet Plug formation
C) The Coagulation Cascade - leads to Clot formation
Platelet factors and/or injured cells activate a series of factors in the blood, which ultimately activate the enzyme Thrombin. Thrombin in turn acts on the soluble protein Fibrinogen to produce the insoluble, filament forming Fibrin protein. Finally Fibrin creates a mesh that covers/seals the wound forming a clot.
Production of Blood Cells
bone marrow
"multipotent stem cell"-hemocytoblast
1) an erythroblast lineage to RBCs
2) a megakaryoblast lineage to platelets
3) or toward white blood cells
a) via the lymphoid lineage to T and B lymphocytes
b) via the myeloid lineage through
monoblasts to Macrophages myeloblasts to sentinel cells and phagocytes