Ianowski - theme 15 Flashcards
Batch reactor:
Cnidarians (coelenterates). Pulsed input, pulsed output. Batch must be processed before the next one can come in.
Continuous-flow stirred-tank reactor:
Continuous input and continuous output. Contents get mixed. Overflow moves on.
Plug-flow reactor:
Continuous input and continuous output. Contents are different at different points (not mixed).
Divisions of gut tube:
Headgut, foregut, midgut, hindgut
Headgut:
Mouth to glottis. Mouthy things happen here.
Who has tongues?
Chordates.
Swallowing (deglutition): process of reflex
Tongue forces bolus to pharynx. Pharyngeal pressure receptors send impulses to medulla oblongata. Swallowing centre activates all-or-none response.
Where does the swallowing reflex begin?
Pharynx
Stages of swallowing reflex:
Oropharyngeal stage: uvula seals nasal passage, epiglottis covers airways, pharyngeal muscles contract to push food to esophagus.
Esophageal stage: peristalsis of esophagus, relaxation of gastroesophageal sphincter to allow food into stomach.
Foregut:
Esophagus. Conducts food from headgut to stomach.
Leeches have crop. Birds throw up.
Midgut:
Stomach. Storage. Breakdown of macromolecules by liver bile and pancreatic juice. Absorption of products.
Human stomach: parts
Fundus: where esophagus fuses
Body: secretion of acid and mucus
Antrum: muscular to push stuff on
Chyme is formed here
What separates duodenum and stomach?
Pyloric sphincter
Gastric mucosal tissue:
Need to keep acid out. Cells are impermeable and tight junctioned together. Mucus serves as a physical and chemical barrier to penetration.
Parts of the digastric stomach:
Esophagus, groove, rumen, reticulum, omentum, abomasum, pylorus.
Fermentation happens in rumen. Enzyme digestion begins in abomasum.
Central lacteal:
Terminal lymphatic vessel associated with small intestine villi. Important for fat absorption.
Most absorption takes place where? Absorption of what?
Duodenum and jejunum. Fat (passive), carbs (secondary active), protein (secondary active), vitamins.
Hindgut of fermenters:
In large fermenters - plug-flow.
In small fermenters - continuous-flow.
Parts of vertebrate hindgut:
Colon, cecum, and rectum/cloaca.
Vermiform appendix:
In humans and higher apes. Stores lymphocytes. No digestive function.
Regions of the colon:
Ascending, transverse, descending.
Colon size vs diet: (carnivore vs…)
Carnivores have short colons. Omni and herbivores have long colons with expandable side bits (haustra).
What parts of the GI system are controlled by CNS?
Esophagus is controlled. Everything else is myogenic.
BER:
Basic electric rhythm (peristalsis). Amplitude is determined locally/intrinsically by mechano anc chemoreceptors.
Types of muscular contractions:
Peristalsis, segmentation (kneading and mixing)
Enteric nervous system:
Nuclei are inside the cells they control. The only part of PNS that has autonomy.
GI exocrine and endocrine functions:
Endocrine: hormones to circulatory system
Exocrine: digestive enzymes, water, mucus, electrolytes into GI lumen
Mammalian salivary gland (exocrine gland):
Acinar portion: mucin, amylase, water, and electrolytes come in.
Duct portion: further modification of saliva.
Activating pepsinogen:
Acid breaks pepsinogen down into active pepsin.
Who secretes pepsinogen? Who secretes intrinsic factors?
Pep - chief cells
Factors - parietal cells
Phases of stomach secretion regulation:
Cephalic: brain stuff (smell, mental)
Gastric: when food enters stomach. gastrin is produced in response to peptides, stomach stretch, and ANS. gastrin stimulates secretion of HCl and pepsinogen.
Intestinal: gastric inhibitory protein in response to fatty acids. GIP inhibits HCl and pepsinogen. secretin stimulates pancreas and inhibits stomach.
Sugar transport from intestinal lumen to blood:
Glucose and galactose: secondary transport with Na+ by SGLT1. Powered by basolateral Na/K pump.
Fructose: brought in by GLUT5.
GLUT2 transports sugars.
Lipid absorption, a beautiful story:
Bile salts break lipids into monoglycerides, fatty acids, and glycerol. Once inside the cell, ER and golgi reassemble triglycerides and send them out of the cell wrapped in a protein blanket. The blanketed triglyceride is called a chylomicron.
