Endocrine/Digestion/Nutrition Flashcards
Nervous System
Vs.
Endocrine System
Nervous system = Short term cellular communication
vs
Endocrine System = Long term cellular communication
Similarities between
Nervous & Endocrine Systems
- Both use chemical messengers that interact with receptors
- Both use the same chemicals
- Nervous System - neurotransmitters
- Endocrine System - hormones
- Both use Negative feedback Control
- Regulation of other cells/tissues/organs that belong to other systems in pursuit of homeostasis.
Three types of contol over body systems
- Local - internal to system
- Neural Control
- Hormonal Control
Negative Feedback
A decrease in output in response to a stimulus
Endocrine
vs
Exocrine
Endocrine -
- Glandular secretory cells
- release secretions into the ECF
Exocrine -
- Glandular secretory cells
- release secretions onto epithelial surfaces ie Goblet cells in respiratory tract - mucus
Paracrine communication
Vs
Endocrine Communication
Paracrine communication
- secretions released into ECF where it is only going to affect adjacent tissues; ie prostaglandin and the local repair of injured tissue
Endocrine communication
- secretions released into ECF that travel in the bloodstream to affect distant tissues; ie glucagon released by pancreas arrives at liver and skeletal muscle tissue where it is broken down
***If Chemical released into bloodstream has known structure = hormone; if structure is unknown = factor
3 Chemical structures of hormones
- Amino Acid Derivitives
- Peptide Hormones
- Lipid Derivitives
Hormones:
Amino Acid Derivitives
Two common nonessential amino acids:
- tyrosine - amino acid which is precursor of epinephrine and norepinephrine, melatin
- tryptophan
Examples:
Thyroid Hormone = T3, T4 are lipid Soluble; can easily pass through membrane
Catecholamines (Epi, NE) are water solulable, travels easily in bloodstream
Peptide Hormones
Classes of amino acids or small protiens that have endocrine functions
All are water soluble
- ADH - Anti-Diruetic Hormone aka Vasopressin
- OH - Oxytocin
- GH - Growth Hormone
- PL - Prolactin
Lipid Derivitives
derived from steroids or eicosanoids
Steroids - lipid soluble only - travel in bloodstream bound to a protein
Eicosanoids - derived from fatty acids ie. prostaglandin
Parkinsons treatment
Parkinsons is usually the result of decreased Dopamine in the body
Treatment is precursor to Dopamine - L-Dopa which body converts into dopamine
Mechanism of Action
Water Soluble Hormones
Second Messenger
- Endocrine cell releases hormone into ECF
- Hormone travels in blood stream to where it is intended to go (target cell)
At Target cell
- Water soluble hormones that cannot pass through cell membrane will bind to receptor which is typically linked to G-proteins which trigger cascade of reactions(dominos) which activates a second messenger (inside the cell) causing intended effect of hormone
- typical second messengers will be: cAMP, cGMP, Ca2+
Mechanism of Action
Lipid Soluble Hormones
Second Messenger
- use of intracellular receptors
- primarily used for lipid soluble hormones; ie Steroid Hormone or Thyroid Hormone
- diffuse through the cell membrane and interact with the receptor in cytoplasm on an organelle or the nucleus.
***hormones that bind with or interact with the nucleus typically modify or regulate gene expression which leads to an increase in the production of certain proteins ie burn patients and production of catecolemine receptors
***hormones that interact an organelle ie mitochondria - thyroid homones can affect metabolic activity ie increasing/decreasing rate of ATP production
Endocrine cell summary
Endocrine cells make hormones which are released into the ECF which travels in bloodstream to target cell.
Transport of Hormones in the bloodstream
Free - avaliable for work
Bound to protein - transport protein specific to that hormone
Free hormones are typically inactivated within an hour due to:
- diffuses out of bloodstream/binds to target tissue/cell
- absorbed by kidney/liver where it is broken down
- broken down by plasma or interstitial enzymes
Certain % is free and remainder is bound
ie T3 - 0.3% free; remainder is bound
T4 - 0.03% free; remainder is bound
Hormone secretion is controlled
primarily by negative feedback - defined as a decrease in output in response to a stimulus
- Humoral (Local) Control - changes in ECF Composition
- Hormonal Control - changes in the levels of circulating hormones
- Neural Control - Arrival of neurotransmitter at neural-glandular junction; ie hypothalamus is the link between neuro and endocrine systems
Hypothalamus role & function
- it is the link between neuro and endocrine systems
- Secretes regulatory hormones into the anterior pituitary
- releasing hormone
- inhibiting hormone
- synthesizes ADH (anti-diuretic hormone) & OT (oxytocin) - released into posterior pituitary
- Contains Autonomic Nervous System centers that inervate adrenal medulla ⇒ sympathetic activation ⇒ release of E & NE inot blood stream
Endocrine Hirearchy
Hypothalamus (brain)
- exerts control over by secretion of releasing hormone or inhibiting hormone into
Anterior/Posterior pituitary (brain)
- which exerts control over most of the rest of the components of the endocrine system
Thyroid gland (Throat),Parathyroid gland (Throat),
Pineal gland (brain),Thymus (chest),
Adrenal glands (above kidneys)
Heart, Kidneys, Adipose Tissue, Digestive tract
Pancreatic islet, Gonads (ovalles/testes)
Roles:
Hypothalamus
Pituitary
Effector Organ
Hypothalamus - Secretes Regulatory Hormones into Anterior Pituitary which control the activities of the Anterior Pituitary ie ______releasing hormone & ______inhibiting hormone.
Pituitary -
Anterior Pituitary - controlled by either releasing or inhibiting hormones secreted by the hypothalamus
Posterior Pituitary - Driven by Neural signals recieved from the hypothalamus
Effector Organ -
Peptide Hormones released by the Pituitary Gland
Anterior Pituitary - hormonal control
- ACTH - Adrenocorticotropic Hormone
- TSH - Thyroid Stimulating Hormone
- FSH - Folicle Stimulating Hormone
- LH - Luteinizing Hormone
- PRL - Prolactin
- GH - Growth Hormone
- MSH - Melancyte Stimulating Hormone
Posterior Pituitary - neural control
- ADH - Anti-diruetic Hormone
- OT - Oxytocin
***All are water soluble
***All bind to membrane receptors and use cAMP as second messenger
The hypophyseal portal system is
the system of blood vessels that link the hypothalamus and the anterior pituitary in the brain.
ACTH
- Regulated by CRH - Corticotropin Releasing Hormone secreted in Hypothalamus travels through hypophyseal portal system affecting
- Synthesis & Release of ACTH - Adrenocorticotropic Hormone in Anterior Pituitary affecting
- Adrenal Cortex which secretes
- Glucocorticoids which travel in blood stream to target cells and inhibit (negative feedback) production of CRH
**regulation of body fluids and inflammation
TSH
- Regulated by TRH - Thyrotropin Releasing Hormone secreted in Hypothalamus travels through hypophyseal portal system stimulates
- Synthesis & Release of TSH - Thyroid-stimulating hormone in Anterior Pituitary affecting the
- Thyroid gland which causes production of
- T3 & T4 which is released into bloodstream to affect target tissues and inhibit (negative feedback) production of TRH
***T3 & T4 are hormones that stimulate metabolism increase rate of ATP production in mitochondria
FSH
- Regulated by GnRH - Gondadotropin Releasing Hormone secreted in Hypothalamus which travels through hypophyseal portal system affecting
- Synthesis & Release of FSH - Follicle Stimulating Hormone in Anterior Pituitary affecting the
- Ovaries/Testes which secrete
- Estrogen/Sperm Production Hormones which Which travel in bloodstream to target cells and also inhibits (negative feedback) production of GnRH
LH
- Regulates GnRH - Gondadotropin Releasing Hormone secreted in Hypothalamus which travels through hypophyseal portal system affecting
- Syntheesis & Release of LH - Luteinizing Hormone in Anterior Pituitary affect
- Ovaries/testes which secrete
- Progesterone/Estrogen which travel in bloodstream to target cells and inhibit (negative feedback) production of GnRH
***Trigers ovulation and production of testosterone
GH
- Released by GHRH- Growth Hormone Releasing Hormone & GHIH - Growth Hormone Inhibiting Hormone secreted in Hypothalamus travels through hypophyseal portal system affecting
- GH - Growth Hormone secretion in Anterior Pituitary which affects
- Liver which secretes
- Somatomedians which affect amino acid uptake & Protein Synthesis at target cells throughout body and GHIH which inhibits (negative feedback), the Liver determines need for continued production (positive feedback) of GHRH
PRL
- Regulated by PRH - Prolactin Releasing Hormone & PIH - Prolactin Inhibiting Hormone secreted in Hypothalamus which travels through hypophyseal portal system stimulating
- Synthesis & Release of PRL - Prolactin in Anterior Pituitary which affects
- Mammary Gland which secretes
- PRH stimulates (positive feedback) or PIH which inhibits (negative feedback) production of more PRL
MSH
Melancyte Stimulating Hormone
has effects during fetal development
ADH
Antidiruetic Hormone
synthesized by the neurons in the hypothalamus where they travel and are released in Posterior Pituitary
released due to
- positive electrolyte concentration
- increase positive osmotic pressure
- Decrease Blood Volume - in order to decrease water lost in urine, and increase reabsorption;
- Can cause vasoconstriction; Vasopressin is ADH
***ADH is inhibited by alcohol
OT
Oxytocin
synthesized by the neurons in the hypothalamus where they travel and are released in Posterior Pituitary
- Stimulates smooth muscle contractions in urterine wall during labor & delivery
- participates in milk let down by mamary’s
- plays a role in sexual arousal
Diabetees Insipidus
decrese in release of ADH
or
decrease in kidney’s response to ADH
indicated by polyuna ⇒ leads to dehydration
Thyroid Gland
- The thyroid gland controls how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones
- TRH - Thyropin Releasing Hormone secreted by hypothalamus delivered to Anterior Pituitary causing release of TSH - Thyroid Stimulating Hormone
- TSH stimulates the Thyroid Gland to synthesize T3 & T4 in the follicular cells from Iodine ion obtained from the diet and Tyrosine an amino acid
T3 & T4
Primarily responsible for the regulation of metabolism
increases rate of ATP production in mitochondria
byproduct of ATP production causes increase in body temp and production of heat
Thyroid Hormone = T3, T4 are lipid Soluble; can easily pass through membrane
Hyperthyroidism
- increased T3/T4
Graves Disease - auto-immune disease, causes weightloss, tachycardia, new onset A-Fib
can cause thyroid to enlarge to 2x normal size (goiter), bulging eyes
typically thin and skinny due to increased caloric burn from hypermetabolic state
Prolonged A-fib can cause remodeling of heart and perminant arrythmia
Thyroid Storm
S&S: Irritability, coma, hypertension, tachycardia
Fatal if not treated within 48 hours
Hypothryoidism
- decreased levels of T3 & T4 (thyroid hormone) in the bloodstream
causes :
- Myxedema - connective tissue disorder, (Epidermis, dermis, subcutaneous) cutaneous dermal edema,
- **Goiter ** (can occur in hyperthyroidism aswell) - enlarged Thyroid Gland - Increase in TSH and decrease in T3&T4
- Cretinism - Congenital hypothyroidism which causes stunded mental and physical growth
Treatment of Hypothyroidism
Supplemental T4 via
Synthroid/Levothyroxine
Bound & Free T3 & T4
Free T3 = 0.3%
Free T4 = 0.03%
Because of the large amounts of bound T3 & T4, bound hormone supply could last for more than a week, making the patient asymptomatic for up to a week.
Blood Ca2+ Regulation
C-Cells/Parafollicular cells of Thyroid via secretion of Calcitonin
vs
Cheif Cells of Parathyroid via secretion of PTH and Calcitrol
C-Cells - Parafollicular cells (Thyroid)
- Opposes the parathyroid
- Responsible for blood Ca2+ regulation by secretion of calcitonin
- If blood Ca2+ level is increased calcitonin is secreted
- inhibits release of stored Ca2+ from bone
- Increase Ca2+ excretion from kidneys
Calcitonin
- Produced by C-Cells aka parafollicular cells of Thyroid Gland
- If blood Ca2+ level is increased secreted
Acts by
- inhibiting release of stored Ca2+ from bone
- Increasing Ca2+ excretion from kidneys
parathyroid gland
4 glands located on back side of thyroid gland
control the amount of calcium in the blood and within the bones
Chief cells (parathyroid) release PTH (parathyroid Hormone) in response to decreased levels of Ca2+ in the blood
Chief Cells of the Parathyroid
PTH - Parathyroid Hormone produced in response to decreased levels of Ca2+ in the blood
Causing
- increase Ca2+ release from bone
- decrease Ca2+ excretion from kidneys
- Stimulate calcitrol (hormone) which increases Ca2+ absorbtion in digestive tract
calcitrol
a hormone which increases Ca2+ absorbtion in the digestive tract
Adrenal Gland
Location and Anatomy
Sits retro peritoneal to abdominal cavity on top of kidneys
Triangular shaped
Outside is the adrenal cortex; inside is the adrenal medulla
Adrenal cortex is responsible for production of steroid hormone (corticosteroids)
- 3 Categories of Steroids
- Mineral Corticoid
- Glucocorticosteroids
- Androgen (hormone)
Adrenal Medulla is responsible for E & NE production and release
Mineral Corticoid
- responsible for maintaining your internal electrolyte composition
- primary example is Aldosterone which is responsible for the conservation of Na ions and water, and secretion of K causing an increase in BP
Glucocortico Steroids
Responsible for Glucose metabolism
CRH (Corticotropin Releasing hormone in Hypothalamus) stimulates ACTH (Adrenocorticotropic Hormone) secretion which stimulates the adrenal cortex to produce
- Cortisone - along with adrenaline are the main hormones released in response to stress; elevating BP and preparing for fight or flight; used to reduce inflammation
- Cortisol - aka Hydrocortisone - primary functions is to increase blood sugar by maintaining glucose levels in bloodstream and anti-inflammatory effects - supresses WBC = longer wound healing
Glucose sparing
Cortisol reduces how much tissues like skeletal muscle take up from the blood, ensuring that the blood will carry enough glucose to supply the brain which can not use other molecules for fuel
Stress and sleep deprivation can cause higher Cortisol levels in the blood ≈ easier to gain weight
Androgen
Sex cell / Reproductive Hormone
Most common is Testosterone, Progesterone
Adrenal Medulla
Responsible for production of Epinephrine and Norepinephrine
Both are continuouslly produced/released
Sympathetic Activation dramatically increases the rate of E & NE release
Adrenal gland syndromes & diseases
- Cushings Syndrome - Longterm elevated glutocorticoids
- leading to DM, +atheriosclerosis, +Na retention, +blood volume.
- Presents with weight gain with spaing of the limbs, round face
- Addisons Disease - chronic adrenal deficency/ insufficency
- autoimmune disorder
- cortisol destruction (hypoglycemia) leading to +Na excretion (aldesterone, mineral corticoid) and K retention ≈ hyperkalemia
- potentiates electrolyte imbalance
Pancreas
Sits retroperitoneal in abdominal cavity, approx dead center
Part of both the Digestive system 99% and the Endocrine System 1%
Digestive system = Exocrine secretions onto surface of epithelial tissues ⇒ digestive enzymes
Endocrine system - Endocrine secretions into ECF for management of glucose ⇒ production of insulin and glucagon
Islets of Langerhans
clusters of cells comprising 1% of all pancreatic cells
4 Types of cells
- Alpha cells - production of glucagon
- Beta cells - production of insulin
- Delta cells - slows effects of food absorbtion; supresses insulin & glucagon production; produces peptide hormone similar to GHIH
- F Cells - pancreatic polypeptide that regulates gallbladder & pancreatic enzymes
When BGL is low
glucagon is secreted
- promotes breakdown of glycogen into glucose
- breakdown of fats into fatty acids
- synthesis of glucose - process called “glyconeogenesis”
When BGL is high
Insulin is secreted
- Allows glucose transport into target cells
- glucose utilization & generation of ATP
- helps glucose convert to glycogen
- participates in fat synthesis
- amino acid absorption/protein synthesis
Pancreatic Concerns/Diseases
- Diabeties Melatus
- Type I - Auto Immune destroyed
- Type II - Environmental, can’t keep up with elevated levels of glucose in bloodstream
- Hypo/Hyperglycemia
***Normal Fasting BGL = 70-110***
Digestive System
consists of
Tract & Accessory Organs
Digestive Tract
Mouth
Pharynx
Esophagus
Stomach
Small Intestine
Large Intestine
Rectum/Anus
6 Functions of the Digestive System
- Ingestion : Food enters into the mouth.digestive tract
- Mechanical: Physical Manipulation of food into smaller organic fragments
- Digestion: Chemical breakdown of food into smaller organic fragments
- Secretion: release of water/enzymes/acid
- absorbtion: movement of small molecules (nutrients) vitamins, water, etc. across digestive lining
- excretion: Removal of waste products from body
4 Major Layers of Digestive Tract Tiss
- Mucosa - Consists of: Lamina Propria (connective tissue), Muscularis Mucosa (thin muscle layer), villi & plica
- Sub-Mucosa - Consists of: Nerves & Blood vessels
- Muscularis Externa - Consists of: Two layers (Inner-circular layer, outer-longitudinal layer) of smooth muscle, seperated by a layer of nerves
- Serosa = Visceral Peritoneum consists of : visceral lining (next to organ), peritoneal fluid (sits between visceral & Parietal linings), and Parietal lining
***Acites - excess of peritoneal fluid side effect of kidney or liver disease and heart failure. (“Tight and jelly like skin”)
Perstalsis
vs
Segmentation
perstalsis: rhythmic contractions of smooth muscle to propel food
segmentation: mechanical mixing of materials
Control of digestive tract
Local Control - paracrine communication; chemicals released into ECF affecting small portion of digestive tract ie. the release of histamine and stomach acid in stomach
Neural Control - Parasympathetic stimulation promotes digestion activities. ***Sympathetic inhibits digestion primarially because it shunts blood flow away from digestive processes.***
Hormonal Control - 18 Hormones; increasing/decreasing smooth muscle cell response to neural stimulation
Mesentary
double layer - serous membrane that anchors portions of the digestive tract
Pathway of certain nerves and bloodvessels
Oral Cavity
- Lined by mucous membrane
- Teeth
- Tounge
- Salivary Glands
*Pharanyx
Teeth
- Incisors - blade shaped for clipping and cutting
- Cuspids - Cone shaped for tearing and slashing
- Bicuspids(premolars) & Molars - Flattened Crowns for mashing and grinding
*2 sets of molars, sometimes 3 with wisdom teeth
Tounge
- Mechanical Processing of food
- Manipulation of food for chewing
- Sensory analysis
Salivary Glands
- Parotid - anterior to ear: produces salivary amylase enzyme which is digestive enzyme necessary to break down startches; only part of digestion that begins in the mouth
- SubLingual - Floor of mouth
- SubMandibular - Floor of mouth
Pharynx
Common pathway for food and air
Contains muscles that are responsible for swallowing
Esophagus
- 10 Inches long; 3/4 in diameter
- Upper Esophageal Sphincter
- Top Third - Skeletal Muscle
- Middle Third - Skeletal & Smooth Muscle
- Bottom Third - Smooth Muscle
- Lower Esophagus Sphincter - normally contracted to keep stomach acid out of esophagus
*Heart Burn is result of weakened or relaxed lower esophageal sphincter
**Esophageal Hiatus - hole in diaphram that allows passage of esophagus into stomach
***Hiatial Hernia - When tear forms at hiatus and intestines pass into lower pressure cavity above diaphram
Swallowing (deglutiton)
begins voluntarially ⇒ involuntary
*Tounge compacts food into bolus
1 - Oral Phase
*Compression of bolus against hard palate
2- Pharyngeal Phase
*bolus contacts sensory receptors in pharynx, initiates involuntary swallowing reflex
*muscles contract, forcing food through the upper esophageal sphincter
3- Esophageal Phase
* bolus pushed towards stomach via peristalsis
Stomach has four major parts
- Cardia - Where the contents of the esophagus empty into the stomach.
- Fundus- Formed by the upper curvature of the organ
- Body -The main, central region
- Pyloris - The lower section of the organ that facilitates emptying the contents into the small intestine
*Pyloric Spincter - Empties into the small intestine
Pyloric stenosis
- is a condition that causes severe projectile non-bilious vomiting in the first few months of life.
- There is narrowing (stenosis) of the opening from the stomach to the first part of the small intestine known as the duodenum, due to enlargement (hypertrophy) of the muscle surrounding this opening (the pylorus, meaning “gate”), which spasms when the stomach empties.
Stomach Facts
- Can hold approximatle 1-1.5 liters of food
- When empty, colapses flat on itself, internal foldin wall called the gastric Rugae
- 3 Muscular layers
- Longitudinal
- Circular - which controls the movement of chyme into the duodenum and forms pyloric spinchter
- inner-oblique - This layer is responsible for creating the motion that churns and physically breaks down the food. It is the only layer of the three which is not seen in other parts of the digestive system.
*myenteric plexus is found between the outer longitundinal and the middle circular layer and is responsible for the innervation of both (causing peristalsis and mixing)
Mucous Membrane of Stomach
&
Gastric Gland
- Comprised of thousands of gastric pit/glands that secrete hormones/enzymes and secretions onto the surface of the stomachs epitlelial lining
- Cell types associated with mucosa of stomach
- Mucous cells - provides protective lining of stomach goal is to prevent any absorption from taking place in stomach
- Gastric gland
- parietal cells which produce HCl and intrinsic factor
- Chief Cells - produces pepsinogen (proteolytic enzyme (pepsin)) once activated
*-ogen - precursor to activated form ie nitrogen - nitrate
Gastric Gland - Parietal Cells
Produces
- HCl -
- acts as a barrier against microorganisms to prevent infections and is important for the digestion of food.
- Its low pH denatures proteins and thereby makes them susceptible to degradation by digestive enzymes such as pepsin.
- The low pH also activates the enzyme precursor pepsinogen into the active enzyme pepsin by self-cleavage
- Intrinsic Factor (GIF) - facilitates the absorption of vitamin B12 later on in the small intestine
Gastric Gland - Chief Cells
- release pepsinogen when stimulated by vagus nerve, gastrin & secretin
- works in conjunction with the parietal cell, which releases gastric acid, converting the pepsinogen into pepsin
**-ogen’s must be converted to substrate before they can be used ie nitrogen to nitrate
Chyme
secretions plus partially digested food
which then passes into the small intestine
4 major functions of the Stomach
- Temporary Storage of ingested food
- Mechanical breakdown of ingested food
- breakdown of chemical bonds by acid/enzymes
- Production of intrinsic factor (promotes absoprtion of B12)
Cephallic Phase
Begins when you first see/think about food
stimulation via vagus nerve
initiates secretion of:
muscous
pepsinogen
HCl
Gastric Phase
Arrival of food in stomach:
Space is made avaliable by stretching out to accomodate food intake
Chemoreceptors cause mixing of contents (segmentation)
**Endocrine cells - secrete gastrin into bloodstream which stimulates stomach to increase production of digestive agents
* Muscous/Pepsinogen/HCl* (positive feedback)
Intestinal Phase
Lower esophageal sphincter is closed and pyloric sphincter is open
Chyme begins to enter the small intestine
Endocrine cells cause secretion of:
GIP/Secretin/CCK
which causes negative feedback inhibition of pepsinogen/muscous/HCl
Alcohol & Caffeine
role in digestion
Digestion process is not completed as food enters small intestine
Alcohol & caffeine help to promote gastric motility and gastric emptying
Small intestine
Where 90% of nutrient absorption takes place
Immediatley follows Pyloric Sphincter
20’ long 1-1.6” in diameter
Three parts: duodenum/jejunum/ileum
Duodenum is bottom end of Upper GI, remainder of Small intestine (jejunum, ileum) part of lower GI tract
duodenum
10” long
retroperiotneal - sits along side kidneys and pancreas
recieves food from stomach
digestige secretion from lower pancreas
Bottom limit of upper GI
jejunum
8’ Long
further chemical digestion
nutrient absorption
begining of lower GI
ileum
12’ Long
ends at ileocecal valve which seperates small from large intestine
nutrient absorption
chemical digestion
Villus
- finger-like projections that protrude from the epithelial lining of the intestinal wall
- the villi together increase intestinal absorptive surface area approximately 30-fold and 60-fold
- Villus capillaries collect amino acids and simple sugars taken up by the villi into the blood stream
- Villus lacteals (lymph capillary) collect absorbed fatty acids and lipids and transported in the lymphatic fluid
impact stress and sympathetic stimulation has on digestive tract
and increase in stress and sympathetic stimulation dries the secretions (diverts blood away from digestive tract) which can cause ulcers
GI Hormones involved in stomach and small intestine
Gastrin (promoting)
Secretin (Inhibitory)
Cholecystolkinin (Inhibitory)
Gastric Inhibitory Peptide (Inhibitory)
Gastrin
- promotes GI motility
- increases secretion of muscous/pepsinogen/HCl in stomach which is released by duodenal endocrine cells
Secretin
Addelson:low pH in sm Intestine ⇒ Increase in secretion of bile and buffers
Chyme entering small intestine has low pH due to mixture of food with gastric acid, Secretin inhibits production of gastric acid and promotes production of bile and buffers.
WIKI: regulates the pH within the duodenum by inhibiting gastric acid secretion by the parietal cells of the stomach, and by stimulating bicarbonate production
cholecystolkinin CCK
released due to presence of Proteins/Lipids that are partialy digested ⇒ causes increased secretion of digestive enzymes and production of bile
in high concentration ⇒ it lowers gastric motily
Gastric Inhibitory Peptide (GIP)
- released in response to arrival of fats and carbohydrates in small intestine
inhibits gastric activity (negative feedback)
promotes the release of insulin
Pancreas
1% Endocrine 99% excocrine ⇒ releases pancreatic juices (buffers & enzymes)
- Carbohydrases ⇒ Sugar Starch
- Proteases ⇒ Proteins
- Lipase ⇒ Lipids
- nucleases ⇒ nucleic acids
- watery alkaline mixture which contains sodium bicarb NaHCO3
Pancreatic duct penetrates duodenum (with common bile duct) hepatopic sphincter guards against release of pancreatic juice
**-ase = enzyme
