Integrative Physiology Exam 5 Flashcards

These flashcards cover key terms and concepts from the lecture on Integrative Physiology, focusing on the functions and processes of the gastrointestinal system, metabolism, and hormonal regulation.

6 Basic Digestive Processes

Ingestion --> Secretion --> Motility --> Digestion --> Absorption --> Defecation

Ingestion

Taking in food through the mouth

Secretion

Releasing digestive enzymes, acids, and mucus

Motility

Propulsion of food through GI tract(peristalsis) --> mixing it together(segmentation)

Digestion

Chemical and mechanical breakdown of food into absorbable units

Absorption

Transport of nutrients from lumen of GI tract to blood or lymph

Defecation

Elimination of feces from the body through the anus

Gastrointestinal Tract(GI Tract)

Long tube from mouth to anus forming a continous path for food from ingestion to defecation

Layers of the GI tract

Mucosa --> Submucosa --> Muscularis externa --> Serosa

Four Basic Processes of GI tract

Motility, Secretion, Digestion, Absorption

Enteric nervous system(ENS)

Responsible for local control of digestion

What does the myenteric plexus control?

Smooth muscle in the ENS

What is the function of the myenteric plexus?

Coordinates peristalsis of food

Where is the myenteric plexus located?

Between the circular and longitudinal layers of the muscularis externa

What does the submucosal plexus control?

Glands and endocrine cells in ENS

What is the function of the submucosal plexus?

Responds to chemical envirnment in lumen

Where is the submucosal plexus located?

Submucosal layer of GI tract

Autonomic nervous system regulation of digestion

Parasympathetic: Stimulates digestion; Sympathetic: Inhibits digestion

What features does ENS share with CNS?

Intrinsic neurons, neurotransmitters and neuromodulators, support cells, diffusion barrier, integrating center

Autorhythmicity in GI tract

Smooth muscle in GI tract is able to generate slow waves of rhythmic contrations due to interstitial cells of Cajal(ICCs)

Patterns of motility in GI smooth muscle

Peristalsis and segmentation

Salivary glands components(three large glands that produce saliva)

Parotid, Submandibular, Sublingual

Salivary gland function

Allows for chemical digestion through secretion of salivary amyle that breaks down carbohydrates in food

Components of the mouth

Cheeks, Lips, Palate, Tongue, Teeth, Salivary glands

Pharynx

Conveys food from mouth to esophagus via deglutition(swallowing)

Swallowing of food pathway

Tongue --> Pharynx --> Esophagus --> Lower esophageal sphincter --> Stomach

What is the stomach?

An enlargement in the GI tract.

What is the function of the stomach in the GI tract?

It connects the esophagus to the small intestine.

How much food can the stomach accommodate?

2 Liters

What are the main regions of the stomach?

Fundus, Body, Antrum

Stomach wall layers difference from GI tract layers

Gastric mucosa consists of folds, muscularis externa contrains an external layer of smooth muscle(oblique cells)

Gastric juice composition

HCL, Pepsin, Lipase

What cells secrete HCL?

Parietal cells

What happens when CO2 enters a parietal cell?

CO2 combines with water to form carbonic acid, catalyzed by carbonic anhydrase --> carbonic acid breaks down into H+ and HCO3

How is H+ pumped into the stomach lumen?

H+ is pumped out into the stomach lumen through the H+/K+ ATPase pump, consuming ATP.

How does Cl- enter the parietal cells?

Cl- enters the parietal cells and passively diffuses into the lumen through chloride channels.

What happens to K+ during HCl secretion?

K+ is pumped into the parietal cell from the lumen.

What happens to HCO3 during the HCl secretion?

HCO3 is exchanged for Cl- into the bloodstream.

Stimulators of HCl secretion

ACh, gastine, histamine

How do the HCL secretion stimulators work?

They work synergistically

Inhibitors of HCl secretion

Somatostatin, PGE2, Secretion, CCK

Enzymes involved in protein digestion

Pepsin, Trypsin, Chymotrpsin, Elastate, Aminopeptidase, Carboxypeptidase

Vomiting

Also known as reverse peristalsis --> food exits through mouth

Pancreas

Secretes pancreatic juice containing many digestive enzymes towards duodenum of small intestine

Pancreatic enzymes

Pancreatic amylase, Trypsin, Chymotrypsin, Elastase, Pancreatic lipase, Ribonuclease, Deoxyribonuclease

Liver

Largest gland of the body

What is the function of the liver?

Metabolism of carbohydrates, lipids, and proteins, processing and detoxification of drugs and other hormones, excretion of bilirubin and synthesis of bile salts, storage of nutrients, phagocytosis, activation of vitamin D

Gallbladder

Pear-shaped organ that stores and concentrates bile

How much bile is secreted per day?

1 Liter

Components of small intestine

Duodenum, Jejunum, Ileum

Components of intestinal juice

Water, Mucus, Ions

Function of small intestine

Digestion and absorption of nutrients

Brush Border Enzymes

Located on the small intestine's epithelial cells(microvilli), performing the final step of breakdown

What are carbohydrates absorbed as?

Monosaccharides

What are proteins absorbed as?

Amino acids and peptides

What are lipids absorbed as?

Fatty acids and monoglycerides

How do carbohydrates enter the cells?

Glucose and galactose: Enter cells via SGLT-1(active transport); Fructose: Enter cells via GLUT-5(facilitated diffusion)

How do proteins enter the cells?

Amino acids: Use Na+ dependent co-transporters(active transport); Peptides: Use H+ dependent transporters(active transport)

How do lipids enter the cells?

Bile salts from micelles emulsify and carry lipids into the enterocyte of the cells

How do carbohydrates exit the cells?

They exit into the bloodstream via GLUT-2 and go to the liver through the hepatic portal vein

How do proteins exit the cells?

They exit via facilitated diffusion into the bloodstream and go to the liver through the hepatic portal vein

How do lipids exit the cells?

They enter the lymphatic system and then drain into the bloodstream at the thoracic duct

Absorption of water

Absorbed in the small intestine via osmosis after Na+ absorption

What are lipoproteins?

Transports lipids through the blood due to their hydrophobicity

Types of lipoproteins

Chylomicron, Very low-density lipoproteins(VLDL), Low-density lipoproteins(LDL), High-density lipoproteins(HDL)

Function of the large intestine

Water and ion absorption, feces formed and released, mechanical and chemical digestion

Disorders associated with feces

Diarrhea and Constipation

Phases of digestion

Cephalic, Gastric, Intestinal

Cephalic phase

Prepares the mouth and stomach for food about to be eaten

Gastric phase

Promotes gastric juice secretion and gastric motility

Intestinal phase

Promotes digestion in small intestine and slows digestion in stomach

Regulation of GI Tract Function

Long reflexes integrated in CNS, Short reflexes integrated in ENS

Absorptive state

Ingested nutrients enter blood stream from GI tract to provide energy for body; approximately 4h after eating

Postabsorptive state

GI tract lacks nutrients, and energy for body is supplied by breakdown of internal nutrient storages

Absorptive state reactions

Protein synthesis, glycogenesis, lipogenesis, transport of triglycerides from liver to adipose tissue, and catabolism of glucose, amino acids, and dietary lipids

Glycogenesis

Synthesis of glyocgen taking place in liver cells(hepatocytes) and muscle fibers and stimulated by insulin

Lipogenesis

Synthesis of triglycerides taking place in adipose cells and liver cells(hepatocytes) and stimulated by insulin

Postabsorptive state reactions

Glycogenolysis, lipolysis, gluconeogenesis, and catabolism of fatty acids, lactic acid, amino acids, and ketone bodies

Glycogenolysis

Breakdown of glycogen in hepatocytes and muscle fibers and stimulated by glucagon and epinephrine

Lipolysis

Breakdown of triglycerides in adipocytes and stimulated by epinephrine and hormones such as cortisol and thyroid

Gluconeogenesis

Synthesis of glucose from noncarbohydrate sources in hepatocytes and kidney cortex cells and stimulated by glucagon and cortisol

What results in an increase in ketone body formation?

Fasting and Starvation

Fasted-state metabolism in the liver

Produces glucose from glycogenolysis and gluconeogenesis and ketones from fats

Fasted-state metabolism in fat

Broken down into fatty acids and glycerol by adipose tissue

Fasted-state metabolism in muscles

Supplies liver with amino acids for gluconeogenesis and uses local fuel as energy

Fasted-state metabolism in brain

Uses glucose and ketones to survive; Particularly relies on ketones during prolonged fasting

Homeostatic control of metabolism

Endocrine pancreas secretes hormones insulin and glucagon

What cells secrete insulin and glucagon?

Alpha cells: Glucagon; Beta cells: Insulin

Fed state ratio of insulin and glucagon

High levels of plasma glucose and amino acids results in insulin secretion --> Increased synthesis of glycogen, fat, and protein

Fasting state ratio of insulin and glucagon

Low levels of plasma glucose results in glucagon secretion --> Glycogenolysis, glucogeogenesis, ketogenesis

Energy balance

Precise matching of energy intake to energy expenditure over time

Calories

The unit in which energy content in food is expressed

Energy contents of nutrients

Carbohydrates: 4 kcal/g; Protein: 4 kcal/g; Fat: 9 kcal/g; Alcohol: 7 kcal/g

Glycogen chemical form of storage

Storage glycogen binds water, liver glycogen regulates blood glucose, and muscle glycogen is used to power muscle contractions

Fat chemical form of storage

Little water required for fat storage, energy in fats much harder and slower to access

Metabolism

All of the chemical reactions in the body; extracts, uses, and stores energy

Types of metabolic pathways

Anabolic and catabolic

Anabolic pathways

Building large molecules, seen in absorptive state

Catabolic pathways

Breaking down large molecules, seen in postabsorptive state

Three fates of biomolecules

Immediate use in energy production, synthesis into needed macromolecules, and storage for later use in energy production