The Liver Flashcards
The Liver
- Site for glucose and Fat metabolism
- Burial ground for RBC
-Bile, Hormone (Angiotensinogen, insulin- like growth factor), Urea Production - Glycogen storage
- Detoxification
Pancreas
- Exocrine pancreas = Produce digestive enzymes
- Endocrine Pancreas = Produces hormones such as insulin, glycogen
Esophagus and Oral Cavity
- Secretion = Saliva (salivary glands)
- Digestion = Carbs
- Motility = Chewing and Swallowing
Stomach
- Secretion = HCL (parietal cells), Pepsinogen and gastric lipase (chief cells), mucus and bicarbonate, Gastrin ( G cells), Histamine (ECL cells)
- Digestion = proteins, Fats ( small amount)
- Absorption = Lipid soluble, alcohol and aspirin
- Motility = peristaltic mixing and propulsion (movement of food)
Small Intestine
- Secretion = Enzymes ( enterocytes), mucus (goblet cells), Hormones (CCK, secretin, GIP, etc)
- Digestion = polypeptide, carbs, fat, nucleic acid
- Absorption = AA, small peptide, monosaccharides, FA, cholesterol, nitrogenous water base, monoglycerides, ions, water, minerals, vitamins
- Motility = mixing and propulsion primarily by segmentation, some peristalsis
Large Intestine
- Secretion = Mucus (goblet cells)
- Digestion = None (except by bacterial)
- Absorption = segmental mixing, mass movement for propulsion
Mucosa
- They contain layers of epithelial cells ( these cells are transporting cells, exocrine and endocrine cells, plus Stem cells)
- They contain CT ( lamina propria), small blood and lymph vessels, nerve fibers and wandering immune cells
- Mucularis mucosae
Submucosa
- they are CT with lymphatic and Blood vessels
- Contain submucosal plexus
Muscularis Externa
they contain longitudinal layer of smooth muscles + myenteric plexus
Serosa
they are circular layer of smooth muscles
Smooth Muscle
- Non- straited, Dense bodies (contain actin), myosin, cross bridge arrangement, its thick filament is regulated and have low levels of energy (involuntary movement)
- Poorly developed, elongated, single nucleus, spindle shaped cells
- membrane potential -55mv, low excitability, Autonomic nerve fibers
Smooth Muscle Communication
- Single unit contraction ( contains gap junctions, unisom contractions when stimulated, branched, contain receptors on each cell to accept neurotransmitters, located within the walls of hollow organs e.g bile duct, GI tracts, ureters, uterus and blood vessels
- syncital
Smooth Muscle Communications
- Multi unit contraction ( no gap junction, each cells contract independently when stimulated, found in the iris and the ciliary of the eye, male reproductive duct, piloerector muscles
Smooth Muscle Contraction ( Tonic contraction)
- Muscle is always contracting without relaxation phase
- Found in the orad (upper) region of the stomach and in the lower esophageal, ileocecal and internal anal sphincters
Smooth Muscle Contraction (Phasic contraction)
- Muscle contracts but have time to relax
- Found in esophagus, gastric antrum, small intestine and all tissues involved in mixing and propulsion
Electrical Activity of smooth muscle (slow wave potential)
- Slow wave potential ( Normal resting potential of the GI smooth muscle)
- They are generated without simulation
- when acted upon by Excitatory agents ( Ca2+) at the moment when it is close to its threshold, it will fire AP and contracts
- Interstitial cells pf cajal ( ICC) located in the myenteric plexus
Fate of Ca2+ in Smooth Muscle
Ca comes in - Binds with Calmodulin (CAM) to form a complex - The complex will bind with Myosin light chain Kinases (MLCK), the MLCK complex will be phosphorated - Contraction occur
Motility of Smooth Muscle
- Electrical activity (AP) always precedes mechanical activities ( Contractions)
- Contraction will aid grind, mix and fragment food so they can be digested and absorbed + they propel food towards aboral direction
-
ACh
- Cholinergic
- Cause contraction of sphincters
- Increase salivary secretion
- Increase secretion
- pancreatic secretion
NE
- Adrenergic
- Relaxes the sphincters
- Increases Salivary secretion
Vasoactive Intestinal Peptide (VIP)
- Gotten from the neurons of the enteric NS
- Relaxes the smooth muscle
- Increase intestinal secretion
- Increases Pancreatic secretion
Nitric Oxide -
- Triggers relaxation of smooth muscle cells
Gastrin- Releasing Peptide ( GRP) also known as Bombesin
- Increase Gastrin secretion
Opiates ( Enkephalins)
- Decreases intestinal secretion
Neuropeptide Y
- Decreases intestinal secretion
Substance P
Increases salivary secretion
Smooth Muscle Reflexes ( Long Reflex)
Send signal to the CNS from the receptor inside and outside of the GI tract
Smooth Muscle Reflexes ( Short Reflex)
- The stimulus is sensed by the receptors within the GI tract and the information is entirely process in the enteric NS
- They occur in the GI without communicating with the CNS
Gastrin
- ECL and parietal cells
- Stimulate gastric acid secretion and mucosal growth
- Will be inhibited by Somatostatin
Cholecytokinin (CCK) or I cells
- Target is gallbladder, pancreas and stomach
- I cells
- Stimulate gallbladder contraction and pancreatic enzyme secretion
- Stop gastric emptying and acid secretion
- Promote satiety ( help us feel full)
- Can act as neurotransmitter
Secretin ( S cells)
- Target is pancreas and stomach
- They stimulate bicarbonate secretion
- inhibit gastric emptying and acid secretion
Motilin ( endo M cells)
- Works in gastric and intestinal smooth muscle
- They stimulate the migrating motor complex
- They will be inhibited by eating a meal
Gastric Inhibitory Peptide ( GIP) also known as K cells (Glucose dependent insulinotropic peptide
- Works on the beta cells of the pancreas
- They stimulate insulin release ( a feed forward mechanism)
- They inhibit gastric emptying and acid secretion
Glucagon Like Peptide -1 ( GLP-1) Also known as L cells
- Works on the endocrine pancreas
- They help stimulate insulin release
- They inhibit glucagon release and gastric function
- They help promote satiety
Ghrelin
- Makes Me hungry ( Increase appetite)
- Pancreas and Adrenal ( Gastric mucosal cells during fasting state)
- Hypothalamus
- Stimulate orexigenic neuron and inhibit anorexigenic neurons
- Loss of activity = obesity as Leptin is inhibited so Pt. keeps eating nonstop
Leptin
- Makes me full ( decrease appetite)
- Increase energy expenditure
- Works on the fat cells ( adipose tissues)
- Hypothalamus
- Stimulate anorexigenic neurons and inhibit orexigenic neurons
Incretins
GLP-1 and GIP
Amylins
- Similar to Incretins except they don’t promote insulin secretion
- They prevent big spike that occurs when eating
- They slow down gastric emptying and decrease plasma glucose thus glycemic control
Oral cavity
- Entry point for food before digestion in the stomach and intestine occur
- Extent of the oral cavity = Lips to oropharyngeal isthmus
- Boundaries = Oral vestibule ( Upper lips innervation will be CN V2, Lower lips will CN V3),
- Lymph drainage = upper lip & lateral lower lips (Submandibular)
Ascending Palatine Artery
Fascial Artery
Venous Drainage of Palate
Branches of maxillary artery and tributaries of pterygoid venous plexus
Sensory Innervation of Palate
CN V2
Motor innervation of palate
All muscle of the soft palate is supplied by CN X except for tensor veli palatini supplied by CN V3
Muscle of the tongue (Extrinsic)
Helps in movement of the tongue
Muscle of the tongue (Intrinsic)
Helps the shape of the tongue
Genioglossus (Extrinsic tongue muscle)
Helps in wagging of the tongue to the contralateral side
Hyoglossus (Extrinsic tongue muscle)
Helps depresses tongue by pulling it side by side + shortens tongue (retrude)
Styloglossus ( Extrinsic tongue muscle)
- Elevate and curls tongue sides
- Work with genioglossus to form a central trough during swallowing
Palatoglossus ( Extrinsic tongue muscle)
- Big boss innervated by pharyngeal plexus (CN X)
- Elevate posterior tongue ( depresses soft palate)
- Constrict the isthmus of fauces (L. the throat)
Superior Longitudinal (Intrinsic tongue muscle)
- Curls tongue upward
- Elevate apex and side of tongue
- Shorten tongue
Inferior Longitudinal ( Intrinsic tongue muscle)
- Curls tongue downward
- depresses apex of tongue
- shortens tongue
Transverse ( Intrinsic tongue muscle)
narrows and elongate (protrude) tongue
Vertical ( intrinsic tongue muscle)
flattens and broadens the tongue
Motor innervation of tongue
all muscle of the tongue is supplied by Hypoglossal Nerve (CN XII) except palatoglossus muscle supplied by pharyngeal plexus ( CN X)
Sensory innervation of tongue (Anterior 2/3rd)
- Lingual Nerve ( CN V3) = general sensation
- Chorda tympani Nerve (CN VII branch) = Taste sensation
Sensory innervation of tongue ( Posterior 1/3rd)
- CN IX = both general and taste sensation
Sensory innervation of tongue (small area in front of the epiglottis)
- Internal Laryngeal nerve = CN X
Injury to tongue ( clinical correlates)
- Injury to Hypoglossal Nerve ( CN XII) = tongue deviate to the paralyzed side during protrusion because of the action of the unaffected genioglossus on the other side
- Injury to the Pharyngeal plexus, the soft palate (uvula) deviates to the opposite side due to unopposed action of opposite side muscle
Lymph drainage of tongue (posterior 1/3rd)
Superior deep nodes on both sides
lymph drainage of the tongue ( medial part of anterior 2/3rd)
Inferior deep cervical nodes
lymph drainage of tongue ( lateral part of anterior 2/3rd)
Submandibular nodes
lymph drainage of tongue ( Apex and frenulum)
Submental nodes
Lymph drainage of tongue ( Posterior 1/3rd area near midline groove)
Drains bilaterally
Salivary Glands ( secretes saliva)
- Parotid glands
- Submandibular glands
- Sublingual glands
Salivary glands
- Lubricates food during mastication
- Keep the mucus membrane of mouth moist
- Begins digestion by secreting Amylase to aid digestion of food bolus
- Serves as intrinsic mouth wash
- Help prevent tooth decay and give us the ability to taste
Parotid gland
- Located between mandible, styloid process and mastoid process
- Parotid sheath ( capsule)
- Have a duct to transport its secretion
Parotid gland structures
- Fascial nerve
- Retromandibular veins
- External carotid artery
Submandibular glands
- Lies along the body of the mandible
- secretion = Mixed
Sublingual glands
- Lies in the floor of the mouth between the mandible and genioglossus muscle
- Secretion = Mucus
Clinical Correlates of the parotid gland
- Mumps = Inflammation of the parotid ( parotiditis) + Pt. present with pain due to stretch of the fascia covering the gland.
- Parotidectomy can be used to relief the pain, just be careful to preserve the facial nerve during procedure as parotid plexus (CNVII (7)) is embedded within the gland
- Testing = CT or MRI
Pharynx
- Extent = Base of base of cranium to cricod cartilage (C6)
- Nasopharynx = behind nose + above palate
- Oropharynx = Behind mouth
- Laryngopharynx = Behind larynx
Pharynx (Oropharynx)
- Digestive function
- Palatine tonsils
- Boundaries = Soft palate, base of tongue, palatoglossal and palatopharyngeal arches