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Lecture Notes - Instructor Adelson > Endocrine/Digestion/Nutrition > Flashcards

Endocrine/Digestion/Nutrition Flashcards

1
Q

Nervous System

Vs.

Endocrine System

A

Nervous system = Short term cellular communication

vs

Endocrine System = Long term cellular communication

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2
Q

Similarities between

Nervous & Endocrine Systems

A
  1. Both use chemical messengers that interact with receptors
  2. Both use the same chemicals
    • Nervous System - neurotransmitters
    • Endocrine System - hormones
  3. Both use Negative feedback Control
  4. Regulation of other cells/tissues/organs that belong to other systems in pursuit of homeostasis.
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3
Q

Three types of contol over body systems

A
  • Local - internal to system
  • Neural Control
  • Hormonal Control
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4
Q

Negative Feedback

A

A decrease in output in response to a stimulus

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5
Q

Endocrine

vs

Exocrine

A

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
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6
Q

Paracrine communication

Vs

Endocrine Communication

A

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

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7
Q

3 Chemical structures of hormones

A
  1. Amino Acid Derivitives
  2. Peptide Hormones
  3. Lipid Derivitives
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8
Q

Hormones:

Amino Acid Derivitives

A

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

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9
Q

Peptide Hormones

A

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
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10
Q

Lipid Derivitives

A

derived from steroids or eicosanoids

Steroids - lipid soluble only - travel in bloodstream bound to a protein

Eicosanoids - derived from fatty acids ie. prostaglandin

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11
Q

Parkinsons treatment

A

Parkinsons is usually the result of decreased Dopamine in the body

Treatment is precursor to Dopamine - L-Dopa which body converts into dopamine

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12
Q

Mechanism of Action

Water Soluble Hormones

Second Messenger

A
  • 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+
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13
Q

Mechanism of Action

Lipid Soluble Hormones

Second Messenger

A
  • 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

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14
Q

Endocrine cell summary

A

Endocrine cells make hormones which are released into the ECF which travels in bloodstream to target cell.

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15
Q

Transport of Hormones in the bloodstream

A

Free - avaliable for work

Bound to protein - transport protein specific to that hormone

Free hormones are typically inactivated within an hour due to:

  1. diffuses out of bloodstream/binds to target tissue/cell
  2. absorbed by kidney/liver where it is broken down
  3. 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
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16
Q

Hormone secretion is controlled

A

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
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17
Q

Hypothalamus role & function

A
  • it is the link between neuro and endocrine systems
  1. Secretes regulatory hormones into the anterior pituitary
    • releasing hormone
    • inhibiting hormone
  2. synthesizes ADH (anti-diuretic hormone) & OT (oxytocin) - released into posterior pituitary
  3. Contains Autonomic Nervous System centers that inervate adrenal medulla ⇒ sympathetic activation ⇒ release of E & NE inot blood stream
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18
Q

Endocrine Hirearchy

A

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)

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19
Q

Roles:

Hypothalamus

Pituitary

Effector Organ

A

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 -

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20
Q

Peptide Hormones released by the Pituitary Gland

A

Anterior Pituitary - hormonal control

  1. ACTH - Adrenocorticotropic Hormone
  2. TSH - Thyroid Stimulating Hormone
  3. FSH - Folicle Stimulating Hormone
  4. LH - Luteinizing Hormone
  5. PRL - Prolactin
  6. GH - Growth Hormone
  7. MSH - Melancyte Stimulating Hormone

Posterior Pituitary - neural control

  1. ADH - Anti-diruetic Hormone
  2. OT - Oxytocin

***All are water soluble

***All bind to membrane receptors and use cAMP as second messenger

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21
Q

The hypophyseal portal system is

A

the system of blood vessels that link the hypothalamus and the anterior pituitary in the brain.

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22
Q

ACTH

A
  1. Regulated by CRH - Corticotropin Releasing Hormone secreted in Hypothalamus travels through hypophyseal portal system affecting
  2. Synthesis & Release of ACTH - Adrenocorticotropic Hormone in Anterior Pituitary affecting
  3. Adrenal Cortex which secretes
  4. Glucocorticoids which travel in blood stream to target cells and inhibit (negative feedback) production of CRH

**regulation of body fluids and inflammation

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23
Q

TSH

A
  1. Regulated by TRH - Thyrotropin Releasing Hormone secreted in Hypothalamus travels through hypophyseal portal system stimulates
  2. Synthesis & Release of TSH - Thyroid-stimulating hormone in Anterior Pituitary affecting the
  3. Thyroid gland which causes production of
  4. 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

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24
Q

FSH

A
  1. Regulated by GnRH - Gondadotropin Releasing Hormone secreted in Hypothalamus which travels through hypophyseal portal system affecting
  2. Synthesis & Release of FSH - Follicle Stimulating Hormone in Anterior Pituitary affecting the
  3. Ovaries/Testes which secrete
  4. Estrogen/Sperm Production Hormones which Which travel in bloodstream to target cells and also inhibits (negative feedback) production of GnRH
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25
Q

LH

A
  1. Regulates GnRH - Gondadotropin Releasing Hormone secreted in Hypothalamus which travels through hypophyseal portal system affecting
  2. Syntheesis & Release of LH - Luteinizing Hormone in Anterior Pituitary affect
  3. Ovaries/testes which secrete
  4. Progesterone/Estrogen which travel in bloodstream to target cells and inhibit (negative feedback) production of GnRH

***Trigers ovulation and production of testosterone

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26
Q

GH

A
  1. Released by GHRH- Growth Hormone Releasing Hormone & GHIH - Growth Hormone Inhibiting Hormone secreted in Hypothalamus travels through hypophyseal portal system affecting
  2. GH - Growth Hormone secretion in Anterior Pituitary which affects
  3. Liver which secretes
  4. 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
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27
Q

PRL

A
  1. Regulated by PRH - Prolactin Releasing Hormone & PIH - Prolactin Inhibiting Hormone secreted in Hypothalamus which travels through hypophyseal portal system stimulating
  2. Synthesis & Release of PRL - Prolactin in Anterior Pituitary which affects
  3. Mammary Gland which secretes
  4. PRH stimulates (positive feedback) or PIH which inhibits (negative feedback) production of more PRL
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28
Q

MSH

A

Melancyte Stimulating Hormone

has effects during fetal development

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29
Q

ADH

A

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

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30
Q

OT

A

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
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31
Q

Diabetees Insipidus

A

decrese in release of ADH

or

decrease in kidney’s response to ADH

indicated by polyuna ⇒ leads to dehydration

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32
Q

Thyroid Gland

A
  • 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
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33
Q

T3 & T4

A

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

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34
Q

Hyperthyroidism

A
  • 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

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35
Q

Thyroid Storm

A

S&S: Irritability, coma, hypertension, tachycardia

Fatal if not treated within 48 hours

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36
Q

Hypothryoidism

A
  • 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
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37
Q

Treatment of Hypothyroidism

A

Supplemental T4 via

Synthroid/Levothyroxine

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38
Q

Bound & Free T3 & T4

A

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.

39
Q

Blood Ca2+ Regulation

A

C-Cells/Parafollicular cells of Thyroid via secretion of Calcitonin

vs

Cheif Cells of Parathyroid via secretion of PTH and Calcitrol

40
Q

C-Cells - Parafollicular cells (Thyroid)

A
  • 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
41
Q

Calcitonin

A
  • 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
42
Q

parathyroid gland

A

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

43
Q

Chief Cells of the Parathyroid

A

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
44
Q

calcitrol

A

a hormone which increases Ca2+ absorbtion in the digestive tract

45
Q

Adrenal Gland

Location and Anatomy

A

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

46
Q

Mineral Corticoid

A
  • 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
47
Q

Glucocortico Steroids

A

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
48
Q

Glucose sparing

A

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

49
Q

Androgen

A

Sex cell / Reproductive Hormone

Most common is Testosterone, Progesterone

50
Q

Adrenal Medulla

A

Responsible for production of Epinephrine and Norepinephrine

Both are continuouslly produced/released

Sympathetic Activation dramatically increases the rate of E & NE release

51
Q

Adrenal gland syndromes & diseases

A
  1. Cushings Syndrome - Longterm elevated glutocorticoids
    • leading to DM, +atheriosclerosis, +Na retention, +blood volume.
    • Presents with weight gain with spaing of the limbs, round face
  2. 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
52
Q

Pancreas

A

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

53
Q

Islets of Langerhans

A

clusters of cells comprising 1% of all pancreatic cells

4 Types of cells

  1. Alpha cells - production of glucagon
  2. Beta cells - production of insulin
  3. Delta cells - slows effects of food absorbtion; supresses insulin & glucagon production; produces peptide hormone similar to GHIH
  4. F Cells - pancreatic polypeptide that regulates gallbladder & pancreatic enzymes
54
Q

When BGL is low

A

glucagon is secreted

  1. promotes breakdown of glycogen into glucose
  2. breakdown of fats into fatty acids
  3. synthesis of glucose - process called “glyconeogenesis”
55
Q

When BGL is high

A

Insulin is secreted

  1. Allows glucose transport into target cells
  2. glucose utilization & generation of ATP
  3. helps glucose convert to glycogen
  4. participates in fat synthesis
  5. amino acid absorption/protein synthesis
56
Q

Pancreatic Concerns/Diseases

A
  • 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***

57
Q

Digestive System

consists of

A

Tract & Accessory Organs

58
Q

Digestive Tract

A

Mouth

Pharynx

Esophagus

Stomach

Small Intestine

Large Intestine

Rectum/Anus

59
Q

6 Functions of the Digestive System

A
  1. Ingestion : Food enters into the mouth.digestive tract
  2. Mechanical: Physical Manipulation of food into smaller organic fragments
  3. Digestion: Chemical breakdown of food into smaller organic fragments
  4. Secretion: release of water/enzymes/acid
  5. absorbtion: movement of small molecules (nutrients) vitamins, water, etc. across digestive lining
  6. excretion: Removal of waste products from body
60
Q

4 Major Layers of Digestive Tract Tiss

A
  • 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”)

61
Q

Perstalsis

vs

Segmentation

A

perstalsis: rhythmic contractions of smooth muscle to propel food

segmentation: mechanical mixing of materials

62
Q

Control of digestive tract

A

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

63
Q

Mesentary

A

double layer - serous membrane that anchors portions of the digestive tract

Pathway of certain nerves and bloodvessels

64
Q

Oral Cavity

A
  • Lined by mucous membrane
  • Teeth
  • Tounge
  • Salivary Glands

*Pharanyx

65
Q

Teeth

A
  • 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

66
Q

Tounge

A
  1. Mechanical Processing of food
  2. Manipulation of food for chewing
  3. Sensory analysis
67
Q

Salivary Glands

A
  • 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
68
Q

Pharynx

A

Common pathway for food and air

Contains muscles that are responsible for swallowing

69
Q

Esophagus

A
  • 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

70
Q

Swallowing (deglutiton)

A

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

71
Q

Stomach has four major parts

A
  1. Cardia - Where the contents of the esophagus empty into the stomach.
  2. Fundus- Formed by the upper curvature of the organ
  3. Body -The main, central region
  4. Pyloris - The lower section of the organ that facilitates emptying the contents into the small intestine

*Pyloric Spincter - Empties into the small intestine

72
Q

Pyloric stenosis

A
  • 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.
73
Q

Stomach Facts

A
  • 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)

74
Q

Mucous Membrane of Stomach

&

Gastric Gland

A
  • 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

75
Q

Gastric Gland - Parietal Cells

A

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
76
Q

Gastric Gland - Chief Cells

A
  • 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

77
Q

Chyme

A

secretions plus partially digested food

which then passes into the small intestine

78
Q

4 major functions of the Stomach

A
  1. Temporary Storage of ingested food
  2. Mechanical breakdown of ingested food
  3. breakdown of chemical bonds by acid/enzymes
  4. Production of intrinsic factor (promotes absoprtion of B12)
79
Q

Cephallic Phase

A

Begins when you first see/think about food

stimulation via vagus nerve

initiates secretion of:

muscous

pepsinogen

HCl

80
Q

Gastric Phase

A

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)

81
Q

Intestinal Phase

A

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

82
Q

Alcohol & Caffeine

role in digestion

A

Digestion process is not completed as food enters small intestine

Alcohol & caffeine help to promote gastric motility and gastric emptying

83
Q

Small intestine

A

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

84
Q

duodenum

A

10” long

retroperiotneal - sits along side kidneys and pancreas

recieves food from stomach

digestige secretion from lower pancreas

Bottom limit of upper GI

85
Q

jejunum

A

8’ Long

further chemical digestion

nutrient absorption

begining of lower GI

86
Q

ileum

A

12’ Long

ends at ileocecal valve which seperates small from large intestine

nutrient absorption

chemical digestion

87
Q

Villus

A
  • 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
88
Q

impact stress and sympathetic stimulation has on digestive tract

A

and increase in stress and sympathetic stimulation dries the secretions (diverts blood away from digestive tract) which can cause ulcers

89
Q

GI Hormones involved in stomach and small intestine

A

Gastrin (promoting)

Secretin (Inhibitory)

Cholecystolkinin (Inhibitory)

Gastric Inhibitory Peptide (Inhibitory)

90
Q

Gastrin

A
  • promotes GI motility
  • increases secretion of muscous/pepsinogen/HCl in stomach which is released by duodenal endocrine cells
91
Q

Secretin

A

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

92
Q

cholecystolkinin CCK

A

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

93
Q

Gastric Inhibitory Peptide (GIP)

A
  • released in response to arrival of fats and carbohydrates in small intestine

inhibits gastric activity (negative feedback)

promotes the release of insulin

94
Q

Pancreas

A

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

Lecture Notes - Instructor Adelson (8 decks)

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