BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Why do we have a digestive system?Provide nutrients to all tissues in the body
What is digestion?
Breakdown of organic molecules/nutrients... mechanical and chemical
What tasks does your digestive system do?
Ingestion, mastication, propulsion, mixing, secretion, digestion, absorption, transportation, elimination
Oral cavity
Pharynx
Esophagus
Stomach
Small intestinesPancreasLiver
Large intestinesRectumAnus
Organ Function Timeingestion/mastication 10-20 sec.secretion/mixing/digestion
transportation 1-2 sec.
transportation/propulsion 5-8 sec.
digestion/secretion 3-4 hrs.mixingdigestion/secretion/mixing 3-5 hrs.absorption/propulsion
absorption/propulsion 18-36 hrs.elimination
What happens between my mouth and anus?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II See Table 24.1
Graphic overview of alimentary canal
What structures exist between mouth and anus?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Graphic overview of …
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
What is the oral cavity and what does it do?
Ingestion (alternate routes)
Mastication = chewingWhich type of digestion? Why?Accomplished via: cheeks, lips, tongue, teeth, jaws
Vestibule: space between cheeks, lips and gums
Oral cavity proper:space within floor of mouth and roof (palate)
Types of teeth:IncisorsCaninesPremolarsMolars
deciduouspermanent
What is the oral cavity and what does it do?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Teeth embedded in:Alveoli in the Maxilla(upper jaw) & Mandible (lower jaw)
Closing jaw =massetertemporalismedial pterygoids
Opening jaw =lateral pterygoids
How do you masticate?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
3 paired glands:ParotidSubmandibularSublingual
Scattered small tubular glands
How do you salivate?
Secrete mucus, serous fluid and enzymes
Endocrine or Exocrine?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Hard and Soft palates
Cleft lip/palate:congenital defect where embryonic tissues fail to fuse
“Because I was different” by Don Bartlette
What can your palate do for you ?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Food formed into a bolus
Pushed against hard palate by tongue
Initiates swallowing reflex
Pharyngeal muscles aid in pushing into esophagus
Swallowing (deglutition) divided into 3 phases:1) voluntary2) pharyngeal3) esophageal
Which of the pharynxes usually conduct food?
How does food get from oral cavity to esophagus?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Conducting Tube
~ 12” in length
2 sphincters:upper esophageal
lower esophageal or cardiac
Generalized layers of alimentary canal
1 2
3
4
What is the role of the esophagus?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Nerve plexus allows local reflexes to be integrated independent of the CNS.
Sensory neurons
Motor neurons
Interneurons
1 2
3
4
What is the role of the enteric plexus?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Varies in size
Rugae (wrinkles) allow distention
Entrance = gastroesophageal opening (cardiac)
Exit = pyloric opening
Muscularis different because 3 layers of muscle
DisordersHiatal hernia & Hypertrophic pyloric stenosis
Endoscopy
What’s unique about the stomique?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
5 types of cells:
1) Surface mucous cells = mucus (1-1.5 mm, alkaline)
2) Mucous neck cells = mucus
3) Parietal cells = HCl, Intrinsic factor (B12)
How does gastric digestion occur?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
5 types of cells:
4) Chief cells = pepsinogen, becomes pepsin in low pH, breaks covalent protein bonds, making peptides
5) Endocrine cells = hormones (gastrin), which stimulates secretory activity of parietal cells.
How does gastric digestion occur?
Gastric secretions and bolus form Chyme
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
How is gastric secretion regulated?Gastric secretion is divided into 3 phases:
1) Cephalic: Stimuli from head region initiate gastric secretion
2) Gastric: Stimuli from w/n stomach cause > secretion
3) Intestinal: Dependent on pH/chemistry of chyme in duodenum. > pH 3 then stimulates, < pH 2 then inhibits.
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
What is important about Liver anatomy?Largest internal organ, 2 major, 2 minor lobes
Connective tissue capsule invades at hepatic portal, form membrane bound lobules (6-sided), portal triads in corners
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Bile production: formed in lobules, drains out hepatic ducts, secreted and/or stored in gall bladder.Storage: can store nutrients (glycogen, vitamins, fats)Nutrient interconversion: metabolically “swapped” DetoxificationPhagocytosisSynthesis
What’s the digestive role of the Liver?
What are gall stones?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Exocrine and endocrine functions
Pancreatic juice =
What’s the digestive role of the Pancreas?
Enzymatic component: enzymes essential for all food class digestion. Examples:trypsin = protein amylase = carboslipase = fatsribo and deoxyribonuclease = RNA/DNA
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Pancreatic juice = Aqueous component H2O and HCO3-ions dilute & neutralize acidic chyme.
What is a source of bicarbonate ions?
What’s the digestive role of the Pancreas?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Long segment of alimentary canal… 6 meters
3 regions:
1) Duodenum
2) Jejunum
3) Ileum
What are the regions of the small intestines?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Contains features such as:
plicae circularis (circular folds)villimicrovilli
Why?
Functions include:
Digestion/Mixing/Absorption
What’s the internal anatomy of the small intestines?
Digestive enzymes in association w/ microvilli: disaccharidases, peptidases, nucleases
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Divided into 4 regions:1) Ascending colonbegins at ileocecal valveends at hepatic flexure
2) Transverse colonbegins at hepatic flexureends at spleenic flexure
3) Descending colonbegins at spleenic flexureends at opening of pelvis
4) Sigmoid colonbegins at opening of pelvisends at rectum
RectumAnus Sphincters
What are the components of the colon?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
SecretionAbsorption(form feces)
Normal flora can produce:
Vitamins (K)Flatus
Capable of mass movements
What are the functions of the colon?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
How does it (defecation) happen?
Diarrhea & Constipation
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
•Mass movements
•Colic distension results in defecation reflex w/c is a contraction of rectal tunica muscularis and relaxation of internal anal sphincter.
•If ignored reflex is extinguished.
•If acted upon, voluntary actions result in defecation.
What is the big picture of digestion?
Bile
Small intestine enzymes
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
To understand Digestion and then absorption…
You need to know the component “pieces” molecules of each major nutrient group.
Water = H2O
Vitamins/Minerals = B12, Ascorbic acid (C) etc.
Salts = Positive ion (Ca2+) and negative ion (Cl-) CaCl2
Carbohydrates = Polysaccharides Disaccharides Monosac.
Lipids = triglycerides 3 fatty acids & gylcerol
Proteins = Polypeptides Dipeptides amino acids
What is the big picture of carbohydrate digestion?
Bile
Small intestine enzymes
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Goal: Convert complex carbs (polysaccharides) and disacchrides into monosaccharides
1) Absorbed via 2ndary active transport
2) Facilitated diffusion to blood
3) Monosac. to liver to be converted to glucose and or glycogen
What is the big picture of lipid digestion?
Bile
Small intestine enzymes
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Goal: Convert to fatty acids, glycerol
1) Micelles formed
2) Attach to plasma membrane, lipid components diffuse into epithelium
3) Changed back into triglycerides and coated with proteins. Chylomicrons excreted
4) Chylomicrons move to lacteal, then blood stream
What is the big picture of lipid digestion?
Bile
Small intestine enzymes
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
What is the most dense?
Water
Lipids
Proteins
What is the big picture of lipid digestion?
Bile
Small intestine enzymes
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Bile
Small intestine enzymes
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Goal: Form amino acids
1) Amino acids absorbed via 2ndary active transport and/or diffusion
2) A.a. moved out via active transport
3) Enter blood stream and move to liver
What is the big picture of protein digestion?
Pepsin =
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
polypeptides
What is the big picture of protein digestion?
Trypsin =
Chymotrypsin =
Carboxypeptidase =
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
oligopeptides
oligopeptides
amino acids
What is the big picture of protein digestion?
Carboxypeptidase =
Aminopeptidase =
Dipeptidase =
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
amino acids
amino acids
amino acids
What is the big picture of protein digestion?
What is the big picture of digestion?
Saliva
Gastric juice
Pancreatic juice
Bile
Small intestine enzymes
Carbos Proteins Lipids
amylasePolysacc. Disacc.
Monosacc.
Disacc.amylase
SucraseLactase
Poly, di peptides
tri, di peptides, a. a.
pepsin
trypsin
peptidaseGlycerol, fatty acids
lipase, esteraselipase
bile salts
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Top Related