6. gastrointestinal system Flashcards

Question

what type of epithelium lines the nasopharynx portion of the pharynx?

Answer 1

ciliated pseudostratified columnar epithelium

Answer 2

moist stratified squamous epithelium

Answer 3

superiorly= laryngopharynx inferiorly= stomach

Answer 4

(muscular tube) 25cm long 2cm wide

Answer 5

oesophageal hiatus

Answer 6

the opening through in the diaphragm through which the oesophagus passes from the thoracic cavity to the abdominal cavity?

Answer 7

(mucosa) moist stratified squamous epithelium

Answer 8

outer longitudinal inner circular

Answer 9

structures that regulate the flow of food and liquids into and out of the oesophagus and prevent reflux. 1. upper oesophageal 2. lower oesophageal (cardiac)

Answer 10

Prevents gastric contents from refluxing into the oesophagus, protecting against heartburn and acid damage.

Answer 11

Prevents air entry into the 0esophagus during breathing, and controls the passage of food from the pharynx into the oesophagus during swallowing.

Answer 12

1. fundus 2. body 3. pyloric region *cardia=smallest region, located near the esophagus where food enters the stomach

Answer 13

1. cardiac sphincter 2. pyloric sphincter

Answer 14

The pyloric sphincter is a muscular valve that controls the passage of partially digested food (chyme) from the stomach into the duodenum (the first part of the small intestine)

Answer 15

(mucosa) - simple columnar epithelium - form tube-like gastric pits - gastric pits form entrance into tubular gastric glands - 5 types of epithelial cells in the pit and gland

Answer 16

1. outer longitudinal 2. middle circular 3. inner oblique

Answer 17

continuous sheet of serous membrane

Answer 18

1. parietal peritoneum lines the abdominal and pelvic cavities 2. visceral peritoneum covers most abdominal organs (peritoneal cavity= potential space between two peritoneum)

Answer 19

potential space between two peritoneum

Answer 20

behind peritoneum inside the peritoneum

Answer 21

lines the abdominal and pelvic cavities

Answer 22

covers most abdominal organs

Answer 23

connect organs to each other or the abdominal wall

Answer 24

mesenteries

Answer 25

>6m; from pyloric sphincter of stomach to ileocecal junction

Answer 26

1. duodenum (~30cm) 2. jejunum (~2.5m) 3. ileum (~3.5m)

Answer 27

duodenum (~30cm)

Answer 28

- extends from pyloric sphincter to jejunum - c-shaped structure adjacent to head of pancreas - short superior part (only section of duodenum peritonised, i.e. within peritoneal lining) - descending part; major and minor duodenal papillae

Answer 29

short superior part [peritonised= within peritoneal lining]

Answer 30

- extends from duodenojejunal flexure to the ileum - completely peritonised

Answer 31

- extends from the jejunum to the large intestine to the ileocecal junction - completely peritonised

Answer 32

plicae circularis (circular folds)

Answer 33

Rugae and plicae circulares are both folds or plicae found in different parts of the digestive system, and they serve to increase the surface area for digestion and absorption. RUGAE: temporary folds in the stomach that allow for expansion and mixing of food PLICAE CIRCULARES: permanent circular folds in the small intestine that enhance nutrient absorption by increasing surface area

Answer 34

- found in stomach - temporary, longitudinal folds in the mucosal layer of stomach - visible when stomach is empty and allow it to expand - composed of gastric mucosa (epithelial cells), involved in secreting gastric juices that aid in digestion

Answer 35

- found in small intestine (duodenum, jejunum, part of ileum) - permanent circular folds of the mucosal and submucosal layers of small intestine - function to increase surface area for absorption - composed of the mucosa and submucosa and contain numerous villi which further increase surface area

Answer 36

brunner glands

Answer 37

peyer patches

Answer 38

simple columnar epithelium

Answer 39

1. absorptive (digestive enzymes) 2. goblet (mucus) 3. granular/Paneth (lysozyme) 4. endocrine (hormones)

Answer 40

intestinal glands

Answer 41

1. absorptive 2. goblet

Answer 42

1. granular 2. endocrine

Answer 43

blood capillary network and lymphatic capillary of villi

Answer 44

1. reabsorbs water 2. compacts intestinal contents into faeces 3. absorbs vitamins 4. houses >700 species of bacteria 5. storage of faecal material

Answer 45

- extends from ileocecal junction to anus - opening between ileum and large intestine guarded by fold of mucous membrane (ileocecal sphincter/valve)

Answer 46

ileocecal sphincter/valve (a fold of mucous membrane)

Answer 47

- first part of large intestine, situated at junction between ileum (small intestine) and ascending colon - serves as reservoir for material received from ileum and is where initial water and salts absorption begins; also has appendix attached to it

Answer 48

- between ileum and cecum (right side of abdomen) - control flow of chyme (partially digested food) from ileum into cecum; prevents backflow of material from cecum into ileum

Answer 49

- attached to cecum (lower right part of abdomen) - unclear function (play a role in immune system/store beneficial gut bacteria??)

Answer 50

- runs upward on the right side of the abdomen from cecum to right hepatic flexure - absorbs water, salts, some nutrients; stores remaining waste before it moves to transverse colon

Answer 51

- sharp bend in colon where ascending colon turns to become the transverse colon - facilitates transition of contents from ascending colon to transverse colon

Answer 52

- runs horizontally across abdomen from right hepatic flexure to left splenic flexure - continues process of absorbing water and salts and stores remaining waste material; houses beneficial bacteria which help with fermentation of undigested food

Answer 53

- bend where the transverse colon turns down into descending colon - marks transition from the more absorptive, wider portion of the colon to the part responsible for further processing waste

Answer 54

- runs downward on left side of the abdomen from left splenic flexure to sigmoid colon - continues absorbing water and electrolytes, stores solid waste material until it is ready to move to rectum

Answer 55

- s-shaped section of colon, located between descending colon and rectum - stores faecal material until its ready to be eliminated

Answer 56

- final section of large intestine, leading from sigmoid colon to anal canal - stores faecal matter until it is ready to be excreted through anal canal; plays role in regulating passage of stool by sensing pressure and stretch

Answer 57

- short terminal part of digestive tract - contains internal and external anal sphincters which control release of faeces

Answer 58

internal sphincter is involuntary external sphincter is voluntary *allowing for conscious control of defecation

Answer 59

ileocecal valve cecum (appendix) ascending colon right hepatic flexure transverse colon left splenic flexure descending colon sigmoid colon rectum anal canal

Answer 60

- simple columnar epithelium - no villi/plicae - mucosal lining formed into straight tubular glands (crypts)

Answer 61

1. absorptive 2. granular 3. goblet (predominate)

Answer 62

simple columnar epithelium

Answer 63

crypts (straight tubular glands)

Answer 64

- outer longitudinal and inner circular layer - longitudinal forms 3 bands- taeniae coli - taeniae coli contractions gather colon into poches; haustra - haustra permit expansion and elongation of intestine

Answer 65

outer longitudinal inner circular

Answer 66

3 bands (taeniae coli)

Answer 67

haustra (pouches)

Answer 68

expansion and elongation of intestine

Answer 69

epiploic (omental) appendages *fat-filled pouches

Answer 70

Most part of the intestine is lined on its outer surface by a sheath of protective layer, the serosa, which consists of a continuous sheet of squamous epithelial cells, the mesothelium, separated from the underlying longitudinal muscle layer by a thin layer of loose connective tissue. The serosa (or serous membrane) is a smooth tissue that forms the outer membrane of the intestines. Adjacent to the serosa, the muscularis externa or muscular layer propels foodstuffs and wastes unidirectionally by peristalsis. The next layer, the submucosa, supports blood and lymph vessels as well as lymphoid tissue.

Answer 71

transverse rectal folds

Answer 72

simple columnar epithelium with tubular glands housing large numbers of mucus-secreting goblet cells

Answer 73

thick muscular tunic of rectum- thick layer composed of both inner circular and outer longitudinal smooth muscle, which is crucial for peristalsis and fecal storage/expulsion.

Answer 74

- superior part: simple columnar epithelium arranges in longitudinal folds (anal columns- arteries and veins) - anal sinuses between columns exude mucus - inferior part stratified squamous epithelium

Answer 75

superior = simple columnar epithelium inferior = stratified squamous epithelium

Answer 76

exude mucus

Answer 77

internal (involuntary) anal sphincter

Answer 78

skeletal muscle

Answer 79

thickening of the inner circular muscle layer (muscularis)

Answer 80

1. upper oesophageal sphincter 2. pyloric sphincter 3. ileocecal valve 4. internal anal sphincter

Answer 81

1. chemical digestion 2. lubrication 3. signalling 4. protection 5. activation of enzymes 6. excretion of waste

Answer 82

exocrine = produce and secrete substances onto an epithelial surface by way of a duct endocrine = secrete their products, hormones, directly into the blood rather than through a duct

Answer 83

acid, pepsin, gastric lipase

Answer 84

secretion, storage and modification of bile

Answer 85

secretion of lubricating fluid containing enzymes that break down carbohydrate

Answer 86

exocrine cells secrete buffers and digestive enzymes, endocrine cells secrete hormones

Answer 87

secretion of digestive enzyme

Answer 88

exocrine glands (secrete saliva via a duct)

Answer 89

each (600-1000) is an individual exocrine gland with its own duct

Answer 90

in mucosal lining of oral cavity, particularly the lips, cheeks, palate

Answer 91

99.4% water remaining 0.6% contains - mucins - electrolytes (Na+, Cl-, HCO3-) - antibodies - enzymes (amylase and lingual lipase)

Answer 92

1. buffer (ions keep pH at ~7) 2. keeps mucosa moist (protects against mechanical damage and essential for speech) 3. solvent (dissolves chemicals in food to aid detection by taste receptors)

Answer 93

saliva can be more watery (serous) or more viscous (mucous)

Answer 94

secrete a watery, enzyme-rich fluid that helps in the digestion of food, particularly amylase, which begins the breakdown of starches in the mouth

Answer 95

some salivary glands, particularly in the submandibular gland, have mixed acini that contain both serous and mucous cells. [the serous cells secrete the watery, enzyme-rich portion, while the mucous cells secrete a thicker, more viscous fluid]

Answer 96

in certain mixed acini, the serous cells are arranged in crescent-shaped cluster called serous demilunes.

Answer 97

Produce a thicker, more viscous secretion. This secretion contains mucin, a glycoprotein that provides lubrication and protects the oral mucosa.

Answer 98

modify the secreted fluid as it passes through the ducts, adjusting the concentration of electrolytes. the epithelial cells lining the pancreatic ducts, which deliver enzymes from acinar cells to the duodenum, and also secrete bicarbonate to neutralize stomach acidity as saliva moves through the intercalated ducts, striated ducts, and excretory ducts, sodium and chloride are reabsorbed; potassium and bicarbonate are secreted

Answer 99

predominantly mucous secretion (viscous, tich in mucin) *one of the three major salivary glands, located under the tongue in the floor of the mouth.

Answer 100

predominantly serous secretion (watery and enzyme-rich)

Answer 101

difficulty swallowing, chewing or speaking.

Answer 102

aids stomach functions - water - hydrochloric acid (HCl) - pepsinogen - intrinsic factor - mucus

Answer 103

innermost layer of stomach involved in production of digestive enzymes, mucus and acids

Answer 104

outermost layer of gastric mucosa. consists of simple columnar epithelial cells that secrete mucus to protect stomach lining from harsh acidic environment.

Answer 105

located beneath surface epithelium. layer of loose connective tissue that contains blood vessels, lymphatic vessels, and immune cells. (provides to epithelium and helps in nutrient absorption)

Answer 106

thin layer of smooth muscle beneath lamina propria. helps in movement of mucosal layer and enhances the secretion of digestive fluids.

Answer 107

beneath muscularis mucosae. layer of connective tissue containing blood vessels, nerves (part of enteric system), and lymphatics. provides structural support to stomach and also aids in nutrient and electrolyte absorption.

Answer 108

a large division of the peripheral nervous system (PNS) that can control gastrointestinal behaviour independently of central nervous system (CNS) input.

Answer 109

the muscle layer of the stomach responsible for mechanical digestion and peristalsis

Answer 110

wave-like muscle contractions that help move food through the digestive tract

Answer 111

1. oblique; innermost layer, runs at an oblique angle 2. circular; middle layer, contract and constricts 3. longitudinal; outermost layer; helps in propelling food along

Answer 112

outermost layer of stomach wall. consists of a thin layer of connective tissue covered by a layer of mesothelial cells that secrete serous fluid to reduce friction between stomach and surrounding structures.

Answer 113

found in gastric glands of stomach, secrete HCl (crucial for digestion), also secrete intrinsic factor which is necessary for vitamin B12 absorption in small intestine

Answer 114

small indentations in stomach lining that lead to gastric glands; contain cells that secrete various substances important for digestion, (e.g. mucus and enzymes)

Answer 115

structures at base of gastric pits within the stomach mucosa.

Answer 116

1. chief cells 2. parietal cells 3. enteroendocrine cells

Answer 117

secrete pepsinogen, inactive enzyme which is converted into pepsin in the acidic environment of stomach and helps breakdown proteins

Answer 118

hormone-producing cells located in gastric glands. secrete gastrin and other hormones that regulate gastric acid secretion and overall digestive function. e.g. G cells secrete gastrin, which stimulates acid production by parietal cells

Answer 119

1. HCl 2. intrinsic factor

Answer 120

needed for absorption of vitamin b12

Answer 121

pH~1-3 kills microbes denatures proteins activates enzymes

Answer 122

1. pepsinogen 2. gastric lipase

Answer 123

pepsinogen; converted to pepsin (active form), breaks certain peptide bonds gastric lipase; splits short-chain triglycerides into fatty acids and monoglycerides

Answer 124

Pepsinogen is activated to pepsin in the acidic environment of the stomach. The activation occurs when the pH drops below around 3.0. More specifically, pepsinogen is converted into its active form, pepsin, when it encounters hydrochloric acid (HCl) secreted by parietal cells. Pepsinogen undergoes a conformational change in response to the low pH, leading to the exposure of its active site and the conversion to pepsin. Pepsin, once activated, works most effectively in a highly acidic environment, with its optimal pH for enzymatic activity being around 1.8 to 3.5. This low pH is crucial for protein digestion and helps to denature proteins, making them easier for pepsin to break down.

Answer 125

secrete mucus (forms protective barrier + has alkaline properties) superficial epithelia mucous neck cells The various mucus-secreting cells in the stomach, including superficial epithelial cells, mucous neck cells, and mucous cells in the gastric glands, work together to create a protective alkaline barrier that shields the stomach lining from the harsh acidic environment and mechanical damage.

Answer 126

superficial epithelia mucous neck cells

Answer 127

endocrine = 2% of cells exocrine = 98% of cells

Answer 128

(2% of pancreatic cells) responsible for producing and secreting hormones that regulate blood sugar levels and other metabolic processes; occurs in specialised cluster of cells known as islets of langerhans. Islets contain different cells types that secrete specific hormones: 1. alpha= secrete glucagon (increases blood glucose by promoting glucose release from liver) 2. beta= secrete insulin (lowers blood glucose levels by facilitating glucose uptake into cells for energy and storage as glycogen) 3. delta= secrete somatostatin (regulates insulin and glucagon) 4. PP= secrete pancreatic polypeptide (involved in regulating pancreatic enzyme secretion and overall digestive system function)

Answer 129

(98% of pancreatic cells) plays major role in digestion by producing digestive enzymes and an alkaline fluid that helps neutralise stomach acid 1. acinar cells = responsible for producing and secreting digestive enzymes; essential for break down of food in small intestine digestive enzymes (amylase, lipase, proteases, nucleases) 2. duct cells = secrete an aqueous NaHCO3 (sodium bicarbonate) solution to neutralise acidic chyme coming from stomach into duodenum (first part of small intestine). Creates optimal pH environment for digestive enzymes to function effectively.

Answer 130

digestive enzymes produced by acinar cells travel through pancreatic duct into duodenum to assist in digestion.

Answer 131

liver produces bile, important for emulsification and digestion of fats. bile travels through bile duct and mixes with digestive enzymes in the duodenum.

Answer 132

amylase; breaks down carbs (starches) lipase; breaks down fats proteases; break down proteins nucleases; break down nucleic acids (DNA, RNA)

Answer 133

water bicarbonate

Answer 134

bicarbonate is alkaline (pH 7.1-8.2) neutralises acid from stomach chyme

Answer 135

1. amylase 2. lipases 3. nucleases *require ions/bile for optimal activity

Answer 136

proteases. secreted in inactive form and activated in duodenum

Answer 137

(proteases- pancreatic enzymes) activated to trypsin by brush border enzyme enteropeptidase

Answer 138

enteropeptidase

Answer 139

secrete glucagon in response to a fall in blood glucose (stimulates glycogenolysis and glucogenesis)

Answer 140

the breakdown of glycogen to form glucose

Answer 141

the synthesis of glycogen without using glucose or other carbohydrates, instead using substances like proteins and fats.

Answer 142

glycogenolysis and glycogenesis [the breakdown of glycogen to form glucose the synthesis of glycogen without using glucose or other carbohydrates, instead using substances like proteins and fats.]

Answer 143

somatostatin [stimulated by cholinergic innervation. inhibits gastrin release]

Answer 144

inhibits release of gastrin from G cells in stomach. gastrin is a hormone that stimulates the secretion of gastric acid (HCl) by parietal cells. therefore somatostatin reduced gastric acid secretion.

Answer 145

released by pancreatic delta in the islets of langerhans release is stimulated by cholinergic innervation (parasympathetic nervous system); activated during digestion *increased gastric acid in stomach/food can trigger somatostatin release; providing negative feedback control of digestive process

Answer 146

also has effect on pancreas: inhibits release of insulin (from beta cells) and glucagon (from alpha cells) in islets of langerhans. helps maintain blood glucose levels.

Answer 147

insulin in response to a rise in blood glucose [inhibited by adrenaline in acute stress- allows cells to utilise glucose]

Answer 148

adrenaline (allows cells to utilise glucose)

Answer 149

hepatocytes (predominant cell type in liver)

Answer 150

1. hepatocytes 2. bile canaliculi 3. bile ductules 4. bile ducts

Answer 151

the digestion and absorption of fats

Answer 152

The main function of bile ducts is to transport bile from the liver to the duodenum for digestion. The bile duct system also leads to the gallbladder, where bile is stored and concentrated until it is needed for fat digestion.

Answer 153

1. Hepatocytes secrete bile. 2. Bile is collected in the bile canaliculi. 3. From the canaliculi, bile flows into the bile ductules. 4. The bile ductules lead to larger bile ducts, which transport the bile to either the gallbladder (for storage) or the duodenum (for digestion)

Answer 154

epithelial tissue Epithelial Tissue is characterized by cells that form the linings of organs and body cavities, as well as glands. Hepatocytes are a specialized form of epithelial cells that perform secretory functions (bile production), which is a key characteristic of glandular epithelium.

Answer 155

An agonist is a molecule capable of binding to and functionally activating a target. The target is typically a metabotropic and/or ionotropic receptor. An antagonist is a molecule that binds to a target and prevents other molecules (e.g., agonists) from binding. Antagonists have no effect on receptor activity.

Answer 156

Bile canaliculi are tiny, 1- to 2-μm wide tissue spaces formed by the apical membranes of adjacent hepatocytes. They form a delicate intralobular network of channels that drain bile produced by hepatocytes.

Answer 157

pH 7.6- 8.6

Answer 158

800-1000mL

Answer 159

waste matter (as urine or sweat but especially feces) discharged from the body.

Answer 160

an excretory product

Answer 161

bile salts bilirubin cholesterol neural fats phospholipids electrolytes

Answer 162

lipid assimilation elimination neutralise gastric acid provides optimum pH for pancreatic enzymes

Answer 163

- thin-walled, pear shaped muscular sac on ventral surface of the liver - stores and concentrates bile by absorbing its water and ions - releases bule via cystic duct, which flows into the bile duct

Answer 164

by absorbing its water and ions

Answer 165

via cystic duct- flows into bile duct

Answer 166

The ventral surface of an organism is the lower surface

Answer 167

ventral surface

Answer 168

- smell, sight, though, taste of food activated CNS - facial, glossopharyngeal and vagus nerves activated - salivary and gastric glands activated - prepared mouth and stomach for food

Answer 169

1. facial 2. glossopharyngeal 3. vagus

Answer 170

The glossopharyngeal nerve is the 9th cranial nerve (CN IX). It is 1 of the 4 cranial nerves with sensory, motor, and parasympathetic functions. It originates from the medulla oblongata and terminates in the pharynx.

Answer 171

- food distends the stomach and stimulates stretch receptors - chemoreceptors in stomach detect increase in pH - leads to peristalsis and gastric juice secretion - chyme empties into duodenum - decrease in pH and decrease in distension - negative feedback loop

Answer 172

- begins when food enters small intestine - inhibits exit of chyme from stomach -> inhibition of gastric motility -> contraction of pyloric sphincter - promotes digestion of food in small intestine - neural enterogastric reflex - hormonal element -> CCK and secretin

Answer 173

The enterogastric reflex is a feedback mechanism that helps regulate the rate of gastric emptying and gastric acid secretion when food enters the small intestine. It slows down gastric processes to allow the small intestine time to process the chyme, ensuring efficient digestion and absorption while preventing irritation or damage to the small intestine from excess acid or food. This reflex is essential for maintaining proper digestive function and intestinal health.

Answer 174

Secretin primarily helps to neutralize stomach acid, protect the duodenal lining, and create an optimal environment for digestive enzyme activity. CCK coordinates the digestive process by promoting bile and enzyme secretion, while slowing gastric motility to ensure that the small intestine has adequate time for digestion and nutrient absorption.

Answer 175

The combined effects of CCK and secretin in the intestinal phase of digestion inhibit gastric secretions by: Reducing gastric acid production (secretin directly inhibits acid secretion, and CCK slows gastric emptying, leading to less acid production). Slowing gastric motility, allowing for better digestion and absorption in the small intestine.

Answer 176

small molecules move through an epithelial barrier into underlying blood/lymphatic vessels

Answer 177

The lumen (plural: lumina) refers to the space within the body's various tubes, tracts, and cavities. Air, blood, fluids, food, and other substances are transported through the lumen to different parts of the body. Lumina are characterized by their patency, meaning they are open and unobstructed in healthy individuals.

Answer 178

large intestine

Answer 179

- chewing (mouth) - churning (stomach) - segmentation (small intestine)

Answer 180

- swallowing (orophraynx) -peristalsis (esophagus, stomach, small + large intestine)

Answer 181

1. simple diffusion 2. facilitated diffusion

Answer 182

Active transport requires energy for the movement of molecules whereas passive transport does not require energy for the movement of molecules. In active transport, the molecules move against the concentration gradient whereas in passive transport, the molecules move along the concentration gradient.

Answer 183

oxygen= simple diffusion sodium= facilitated diffusion glucose= facilitated diffusion fatty acid= simple diffusion

Answer 184

Simple diffusion is the direct transport of molecules across the cell membrane that is allowed by the cell membrane. Facilitated diffusion, on the other hand, occurs through the action of transmembrane proteins such as carrier proteins, channel proteins, and aquaporins.

Answer 185

Primary active transport, also called direct active transport, directly uses chemical energy (such as from adenosine triphosphate or ATP in case of cell membrane) to transport all species of solutes across a membrane against their concentration gradient.

Answer 186

Secondary active transport is defined as the transport of a solute in the direction of its increasing electrochemical potential coupled to the facilitated diffusion of a second solute (usually an ion) in the direction of its decreasing electrochemical potential.

Answer 187

primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient.

Answer 188

the Na+/K+ ATPase on basolateral membrane

Answer 189

The Na+/K+ ATPase is essential for the electrochemical gradients necessary for nutrient and electrolyte transport, which are critical for efficient intestinal absorption. By actively transporting sodium out of the enterocyte, it creates the conditions for secondary active transport of nutrients, water, and other essential molecules across the apical membrane of enterocytes. The Na+/K+ ATPase uses ATP to pump 3 sodium ions out of the enterocyte (into the extracellular fluid) and 2 potassium ions in (into the enterocyte).

Answer 190

1. carbohydrates 2. lipids 3. proteins 4. nucleic acids 5. vitamins 6. minerals 7. water 8. drugs

Answer 191

- long chains of monosaccharides - digestible (e.g. starch) - non-digestible (e.g. fibre, cellulose) - found in rice, pasta, potatoes, cereal etc

Answer 192

digestible= starch non-digestible= fibre, cellulose

Answer 193

- shorter chains (mono/disaccharides) - found in fruit, vegetables, dairy etc - sucrose/lactose

Answer 194

The monosaccharides include glucose, fructose, and galactose. The major disaccharides include sucrose (one glucose molecule and one fructose molecule), lactose (one glucose molecule and one galactose molecule), and maltose (two glucose molecules).

Answer 195

1. mouth: salivary amylase breaks down starch to maltose 2. pancreas: pancreatic amylase breaks down starch to maltose 3. small intestine microvilli: specific oligosaccharides produce monosaccharides

Answer 196

specific oligosaccharides produce monosaccharides the microvilli on the surface of enterocytes play a critical role in carbohydrate digestion and absorption by housing enzymes that break down oligosaccharides into monosaccharides, which are then absorbed through specific transporters.

Answer 197

Enterocytes, or intestinal absorptive cells, are simple columnar epithelial cells which line the inner surface of the small and large intestines

Answer 198

After breaking down throughout the digestive system, monosaccharides are absorbed into the bloodstream. [glucose/fructose/galactose] As carbohydrates are consumed, the blood sugar levels increase, stimulating the pancreas to secrete insulin. Insulin signals the body's cells to absorb glucose for energy or storage.

Answer 199

If someone lacks the enzyme lactase, they cannot properly break down lactose (the sugar found in milk and dairy products) into its two monosaccharide components, glucose and galactose. This condition is called lactose intolerance. bloating, diarrhoea, flatulence, abdominal pain, and nausea after consuming dairy products.

Answer 200

glucose and fructose (disaccharide)

Answer 201

glucose + galactose (disaccharide)

Answer 202

2 glucose molecules glucose + glucose (disaccharide)

Answer 203

1. glucose 2. fructose 3. galactose

Answer 204

Oligosaccharides typically consist of 3-10 monosaccharide units linked by glycosidic bonds. They can be found in various foods and are important for human nutrition. e.g. raffinose (galactose + glucose + fructose) stachyose (galactose + galactose + glucose + fructose)

Answer 205

long chains of monosaccharides - starch - glycogen - cellulose - chitin

Answer 206

Carbohydrates are broken down to an absorbable size at the brush border rather than in the small intestine lumen because this location allows for more efficient digestion, enzyme specificity, control over the digestion-absorption process, and minimized risk of fermentation in the colon. This localized digestion ensures that only monosaccharides, the absorbable form of carbohydrates, enter the enterocytes, enabling efficient nutrient absorption and preventing digestive disturbances.

Answer 207

The brush borders of the intestinal lining are the site of terminal carbohydrate digestions. The microvilli that constitute the brush border have enzymes for this final part of digestion anchored into their apical plasma membrane as integral membrane proteins. in small intestine: The brush border is located on the apical surface of enterocytes in the small intestine (duodenum, jejunum, and ileum). It contains brush border enzymes that play a critical role in the final stages of digestion, particularly carbohydrate digestion.

Answer 208

glucose and galactose - require energy for absorption due to secondary active transport with sodium

Answer 209

Glucose and galactose are the main monosaccharides that are transported against their electrochemical gradient in the small intestine. The transport of these sugars into the enterocytes is facilitated by the SGLT1 transporter, which uses the energy from the Na⁺ gradient (created by the Na+/K+ ATPase pump) to move glucose and galactose against their concentration gradients into the cells.

Answer 210

- long chains of amino acids (polypeptides) - dietary sources of protein include (meat, fish, dairy, eggs, pulses, cereals) - also absorb proteins from digestive juices and dead mucosal cells

Answer 211

1. digestive juices 2. dead mucosal cells

Answer 212

1. stomach; pepsin produces smaller polypeptide chains 2. pancreas; trypsin, chymotrypsin, carboxypeptidase produce small peptide chains 3. small intestine microvilli; specific peptidases, produce tripeptides, dipeptides and amino acids

Answer 213

specific peptidases produce tripeptides, dipeptides and amino acids

Answer 214

trypsin, chymotrypsin, carboxypeptidase produce small peptide chains

Answer 215

pepsin produces smaller polypeptide chains

Answer 216

each amino acid class has a different cohort of transporters

Answer 217

facilitated diffusion

Answer 218

secondary active transport of acidic and neutral amino acids (Na+ gradient) and di- and tri- peptides (H+ gradient)

Answer 219

Na+ gradient

Answer 220

H+ gradient

Answer 221

1. triglycerides 2. phospholipids 3. cholesterol 4. steroids 5. fat-soluble vitamins

Answer 222

1. mouth; lingual lipase digests <10% of lipid most important in neonates 2. stomach; gastric lipase small amount, most important in neonates 3. pancreas; pancreatic lipase, majority of lipid digestion in adults

Answer 223

pancreas (pancreatic lipase)

Answer 224

1. mouth (lingual lipase) 2. stomach (gastric lipase)

Answer 225

monoglycerides and fatty acids (short/long chain)

Answer 226

simple diffusion

Answer 227

clump together

Answer 228

- breaks large lipid droplets into smaller droplets (increases surface area) - begins in stomach with churning - bile salts (hydrophilic and hydrophobic regions)

Answer 229

in stomach with churning

Answer 230

Emulsification is possible due to the amphipathic properties of bile salts. [1] The hydrophilic portion of the bile salts surrounds the lipid, forcing the lipid to disperse as the negative charges repel each other. Bile salts also allow the products of lipid digestion to be transported as micelles.

Answer 231

fatty acids + monoglycerides

Answer 232

micelles formed; 'ferry' them into intestinal mucosa

Answer 233

fatty acids and monoglycerides leave micelles and diffuse into epithelial cells

Answer 234

they are recombined and packages with other lipoid substances and proteins to form chylomicrons

Answer 235

chylomicrons (they are recombines and packages with other lipoids substances and proteins to form chylomicrons)

Answer 236

A lacteal is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine.

Answer 237

sER- smooth endoplasmic reticulum

Answer 238

lipids (mainly triglycerides) are reassembled within enterocytes (small intestine epithelial cells) after being broken down into free fatty acids and monoglycerides. They are then packaged into chylomicrons, which contain 90% triglycerides, 5% cholesterol, 4% phospholipids, and 1% proteins. These chylomicrons are transported through the lymphatic system to deliver lipids to the body.

Answer 239

1. triglycerides (90%) 2. cholesterol (5%) 3. phospholipids (4%) 4. protein (1%)

Answer 240

chylomicrons are extruded from the epithelial cells by exocytosis. they enter lacteals and are carried away from intestine by lymph.

Answer 241

they are too large to enter blood. lymphatic capillaries lack a basement membrane and are more permeable to large particles.

Answer 242

1. vitamin c 2. folic acid 3. thiamine 4. vitamin d 5. vitamin a 6. vitamin b12

Answer 243

carried by micelles then diffuse into absorptive cells (a, d, e, k)

Answer 244

absorbed by passive/active transporters (b, c)

Answer 245

binds with intrinsic factor and is absorbed by endocytosis *water soluble

Answer 246

The intrinsic factor (IF) is a glycoprotein produced by the parietal cells (oxyntic cells) located at the gastric body and fundus. It plays a crucial role in the transportation and absorption of the vital micronutrient vitamin B12 (cobalamin, Cbl) by the terminal ileum

Answer 247

Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested materials.

Answer 248

endocytosis *binds with intrinsic factor and is absorbed by endocytosis

Answer 249

fat = A, D, E, K water = C, B (fat-soluble vitamins are carried by micelles and then diffuse into absorptive cells; water-soluble vitamins are absorbed by passive/active transporters)

Answer 250

vitamin K and B vitamins from bacterial metabolism are absorbed

Answer 251

Vitamin E is a fat soluble vitamin so must be carried via a micelle. bile duct delivers bile so might cause a deficiency. A blockage of the bile duct prevents bile from being released into the small intestine. Since bile is necessary for forming micelles, and micelles are required for the absorption of fat-soluble vitamins like vitamin E, a bile duct blockage leads to impaired absorption of vitamin E, resulting in a deficiency of this important nutrient.

Answer 252

usually active transport, mostly along the length of small intestine

Answer 253

enters via divalent metal-ion transporter 1*

Answer 254

regulated by vitamin D and parathyroid hormone (PTH)

Answer 255

Na+ is couples with absorption of glucose and amino acids

Answer 256

K+ diffuses in response to osmotic gradients

Answer 257

95% is absorbed in small intestine by osmosis

Answer 258

disturbance in mechanisms leads to water loss

Answer 259

solute uptake

Answer 260

the minor component in a solution, dissolved in the solvent.

Answer 261

occurs whenever a concentration gradient is established by active transport of solutes

Answer 262

1. anything that interferes with delivery of bile or pancreatic juice 2. damaged intestinal mucosa (e.g. bacterial infection) 3. gluten-sensitive enteropathy (celiac disease); gluten damages intestinal villi and brush border, treated by eliminating gluten from diet (all grains but rice and corn)

Answer 263

gluten damages intestinal villi and brush border- can lead to malabsorption treated by eliminating gluten from diet (all grains but rice and corn)

Answer 264

glycogen to glucose and vice versa (glycogenesis + glycogenesis), amino acids, synthesises lipoproteins, protein metabolism

Answer 265

glycogenolysis (glycogen to glucose): liver stores glycogen and can break it down to glucose when the body needs energy, especially between meals or during physical activity (glycogenolysis) glycogenesis (glucose to glycogen): when there is an excess of glucose (e.g. after eating), the liver converts glucose into glycogen for storage in a process called glycogenesis. helps maintain blood glucose levels within a healthy range.

Answer 266

glycogenolysis = glycogen to glucose glycogenesis= glucose to glycogen

Answer 267

liver plays a critical role in amino acid metabolism by converting excess amino acids into glucose (glyconeogenesis) or fat (lipogenesis). it also de-aminates amino acids, removing the amino group, which can be converted to urea for excretion.

Answer 268

liver synthesises lipoproteins, such as very-low-density lipoproteins (VLDL), which are involved in the transport of lipids (especially triglycerides and cholesterol) through the bloodstream

Answer 269

liver synthesises many important proteins such as albumin, clotting factors (e.g. fibrinogen), and other plasma proteins essential for maintaining blood volume, osmotic pressure and blood clotting

Answer 270

alcohol dehydrogenase: liver metabolises alcohol (ethanol) using the enzyme alcohol dehydrogenase (ADH), converting ethanol into acetaldehyde, which is then further metabolised to acetic acid and eventually eliminated. other toxins: the liver also detoxifies other harmful substances, including drugs, environmental toxins, and waste products (like ammonia, which is converted to urea for excretion by the kidneys)

Answer 271

bilirubin: liver is responsible for processing haemoglobin from old red blood cells. The heme portion of haemoglobin is converted into bilirubin, which is excreted in the bile and eliminated from the body via faeces. bile production: liver synthesises bile, which is essential for the digestion and absorption of fats and fat-soluble vitamins (A, D, E, K). Bile also aids in the excretion of cholesterol and bilirubin.

Answer 272

glycogen: liver stored glycogen as an energy reserve- can be converted back to glucose when required by body triglycerides: stores triglycerides (fat) as an energy reserve, especially when there is excess food intake or during periods of fasting. vitamins + minerals: liver stores several vitamins (e.g. A, D, B12) and minerals (e.g. iron, in form of ferritin), released when body needs them

Answer 273

liver synthesises bile salts from cholesterol. Bile salts are critical for the emulsification of dietary fats in small intestine making them more accessible to digestive enzymes.

Answer 274

liver synthesises cholesterol, which is essential for building cell membranes, producing certain hormones (e.g. steroids), and synthesising bile salts

Answer 275

liver produces various clotting factors (e.g. prothrombin, fibrinogen) required for proper blood clotting, helping to prevent excessive bleeding

Answer 276

albumin, the most abundant protein in plasma, is produced by the liver and is crucial for maintaining osmotic pressure, which helps to retain water within blood vessels and maintain blood volume

Answer 277

liver produces angiotensinogen, which is involved in the regulation of blood pressure and fluid balance. this protein is converted to angiotensin II by enzymes in the blood, leading to vasoconstriction and increased blood pressure.

Answer 278

liver contains specialised macrophages called Kupffer cells, which are part of the reticuloendothelial system. these cells perform phagocytosis, removing old/damaged red blood cells, pathogens, and other debris from the blood that passes through the liver.

Answer 279

liver is involved in numerous biochemical reactions, many of which are exothermic (release heat). there include metabolic processes like glycogenolysis and lipid metabolism, contributing to the regulation of body temperature.

Answer 280

~1.5kg (largest internal organ)

Answer 281

located in upper right quadrant of abdomen (extends into left quadrant) sits underneath the diaphragm and is well protected by rib cage closely related to: -> right kidney posteriorly -> stomach to right -> colon inferiorly

Answer 282

- divided into large right lobe and smaller left lobe by falciform ligament - inferiorly, right lobe also includes the caudate and quadrate lobes

Answer 283

falciform ligament

Answer 284

visceral surface

Answer 285

(gateway to the liver) main site where structures enter and leave the liver including the: 1. portal triad 2. nerves 3. lymphatics

Answer 286

(part of porta hepatis) 1. hepatic artery (entering) 2. hepatic portal vein (entering 3. bile duct (leaving)

Answer 287

liver has dual blood supply: -> hepatic artery (from coeliac trunk of aorta) -> hepatic portal vein (convergence of veins draining the GI tract) hepatic portal vein is main blood supply to the liver- carries nutrients/toxins absorbed by GI tract hepatic artery is smaller and provides oxygen rich blood

Answer 288

hepatic portal vein (carried nutrients/toxins absorbed by GI tract)

Answer 289

hepatic artery

Answer 290

hepatic artery- from coeliac trunk of aorta hepatic portal vein= convergence of veins draining GI tract

Answer 291

once blood has passed through the liver it is drained into the inferior vena cava by 3 hepatic veins (hepatic veins draining liver not to be confused with hepatic portal vein supplying the liver!)

Answer 292

3 hepatic veins once blood has passed through the liver it is drained into the inferior vena cava by 3 hepatic veins

Answer 293

blood drainage from GI tract, pancreas and spleen is carried to the liver first. key to delivering nutrients/toxins for processing and hormone signalling. *a portal system connects one organ to another without returning to the heart first

Answer 294

a portal system connects one organ to another without returning to the heart first

Answer 295

75-80% of liver cells are hepatocytes (parenchymal cells)

Answer 296

chemical transformation factories; lots of organelles, RER, mitochondria separated from sinusoids (specialised capillaries) by space of Disse (bathes hepatocytes in plasma) membranes of the hepatocytes facing the space of Disse have microvilli= large surface area to facilitate diffusion

Answer 297

space of Disse (bathes hepatocytes in plasma)

Answer 298

specialised capillaries (liver)

Answer 299

microvilli = large surface area to facilitate absorption

Answer 300

fibrosis. (inactive in healthy conditions but store vitamin A and produce collagen when activated)

Answer 301

specialised macrophages form part of the reticuloendothelial system which breaks down red blood cells (RBCs)

Answer 302

in hexagons with branches of the portal triad at each corner and a central vein

Answer 303

sinusoids (blood from the hepatic artery and hepatic portal vein enters specialised capillaries- sinusoids)

Answer 304

run in a network between the hepatocytes, receiving bile secretions, and join to form small bile ducts

Answer 305

large, low pressure vessels Drain blood from hepatic artery and hepatic portal vein in to the central vein. Fenestrated endothelium to facilitate transfer of metabolites between plasma and hepatocytes. Contain Kupffer; specialised macrophages that help recycle senescent red blood cells.

Answer 306

fenestrated endothelium. (to facilitate transfer of metabolites between plasma and hepatocytes)

Answer 307

Kupffer cells (specialised macrophages that help recycle senescent red blood cells)

Answer 308

large, low pressure vessels (specialised capillaries) drain blood from hepatic artery and hepatic portal vein to the central vein

Answer 309

phase I (modification): addition of reactive and polar groups; metabolites. prevents free diffusion across membranes; ready phase II phase II (conjugation): attachment of an ionised group makes the metabolite more water soluble; facilitates transport phase III (excretion): smaller metabolites excreted by the kidney larger metabolites excreted in bile

Answer 310

modification addition of reactive and polar groups- metabolite prevents free diffusion across membranes- ready for phase II

Answer 311

conjugation. attachment of an ionised group. makes the metabolite more water soluble- facilitates transport

Answer 312

excretion smaller metabolites excreted by kidney larger metabolites excreted by bile

Answer 313

primarily performed by cytochrome p450 enzymes located in smooth endoplasmic reticulum (sER) of hepatocytes. enzymatic incorporation of polar groups: (O/OH) - oxidation - reduction - hydrolysis introduced functional groups (oxidation, reduction, hydrolysis) that act as 'handles' for phase II reactions (conjugation) *phase I generally makes drugs more water-soluble for excretion some metabolites may be highly reactive and toxic (e.g. paracetamol)

Answer 314

these enzymes are primarily located in the smooth endoplasmic reticulum (sER) of hepatocytes (liver cells). they catalyse a variety of reactions that introduce functional groups into the drug molecule, making them more polar and more water-soluble.

Answer 315

addition of an ionised group: -> glutathione -> sulphate -> glycine -> glucuronic acid occurs in cytoplasm of hepatocytes makes metabolite water soluble for transport and inactivates it.

Answer 316

conjugation. 1. glutathione 2. sulphate 3. glycine 4. glucuronic acid

Answer 317

(phase II) occurs in cytoplasm of hepatocytes

Answer 318

makes it more water soluble for transport and inactivates it

Answer 319

(excretion) Phase III involves the excretion of metabolites formed during Phase I and Phase II, making them ready for removal from the body. This phase requires active transport by specific transport proteins to move metabolites out of cells and into the urine (via kidneys) or bile (via liver).

Answer 320

mostly broken down by macrophages mostly in the spleen

Answer 321

The spleen is a small organ that stores and filters blood. As part of the immune system, it also makes blood cells that protect you from infection.

Answer 322

bilirubin *bilirubin is released from macrophages into bloodstream and is known as unconjugated bilirubin/free bilirubin

Answer 323

lipophilic (fat-soluble) making it potentially toxic due to its solubility in lipids it can cross cell membranes including blood-brain barrier. this can cause damage

Answer 324

free bilirubin is bound to albumin in the plasma to be transported through the bloodstream to the liver; albumin serves as a carrier preventing bilirubin from causing toxicity while in circulation

Answer 325

a protein in your blood plasma made by liver

Answer 326

free bilirubin is conjugated with glucuronic acid to form water-soluble conjugated bilirubin (in hepatocytes)

Answer 327

conjugated bilirubin is excreted into bile and released into intestines. it is then converted to urobilinogen and either reabsorbed into bloodstream or excreted in the urine and stool.

Answer 328

conjugated to glucuronic acid to form bilirubin glucuronide

Answer 329

more water soluble and can be excreted by hepatocyte into biliary canaliculi

Answer 330

excess plasma bilirubin (yellowing skin)

Answer 331

prior to birth, bilirubin crosses the placenta and is removed by the mother's circulation after birth, the liver conjugates bilirubin which is then excreted into the gastrointestinal tract through the biliary system. in 60% of full term infants, the immature liver does not have sufficient glucuronyl transferase to conjugate bilirubin - hyperbilirubinemia (jaundice) phototherapy oxidises bilirubin to a water soluble form that can be easily excreted by the new-born

Answer 332

glucuronyl transferase *conjugates bilirubin to be more soluble and more easily excreted

Answer 333

phototherapy. phototherapy oxidises bilirubin to a water soluble form that can be easily excreted by new-born.

Answer 334

the brain is an obligate glucose user

Answer 335

leads to impaired nervous system function

Answer 336

complications associated with diabetes

Answer 337

~100mg/100ml liver maintains normal blood glucose level during all metabolic phases (digestive/postabsorptive/fasting/strenuous exercise)

Answer 338

liver. liver maintains normal blood glucose level during all metabolic phases (digestive/postabsorptive/fasting/strenuous exercise)

Answer 339

insulin- anabolic (biosynthesis, requires energy) glucagon - catabolic (degradation, produces energy)

Answer 340

insulin- anabolic (biosynthesis, requires energy) glucagon - catabolic (degradation, produces energy)

Answer 341

-> increased glucose uptake by hepatocytes via GLUT2 receptors -> insulin is released from pancreas in response to elevated blood glucose -> glucokinase converts glucose into glucose-6-phosphate (G6P) inside the liver -> glycogen synthase converts G6P into glycogen for storage (glycogenesis) -> when glycogen storage is full, excess glucose is converted into triglycerides through lipogenesis for fat storage

Answer 342

glucokinase

Answer 343

glycogen synthase converts G6P into glycogen for storage

Answer 344

in your liver and skeletal muscles (the muscles attached to your bones and tendons), with small amounts in your brain. This stored form of glucose is made up of many connected glucose molecules and is called glycogen.

Answer 345

facilitates uptake of glucose into cells, particularly muscle cells, fat cells (adipocytes), and liver cells (hepatocytes) muscle + fat cells: insulin activates GLUT4 glucose transporter which facilitates glucose uptake into these tissues liver cells: insulin promotes glucose uptake through GLUT2 transporters, helping to store glucose as glycogen or convert it into fat if glycogen stored are full

Answer 346

-> glucagon release from pancreas increases when blood glucose is low -> glycogen breakdown in the liver (glycogen phosphorylase) produces glucose-1-phosphate, which is then converted into glucose via phosphoglucomutase and glucose-6-phosphatase -> gluconeogenesis; in absence of sufficient glycogen, the liver synthesises glucose from non-carbohydrate precursors (amino acids and glycerol). This process requires ATP and GTP and involves 11 enzyme-catalysed steps.

Answer 347

Guanosine Triphosphate a molecule that is involved in various cellular processes and serves as an energy source for certain biochemical reactions in the brain.

Answer 348

(in liver) glycogen -> glucose-1-phosphate = glycogen phosphorylase glucose-1-phosphate -> glucose = phosphoglucomutase and glucose-6-phosphatase

Answer 349

1. phosphoglucomutase 2. glucose-6-phosphatase

Answer 350

glycogen phosphorylase

Answer 351

in absence of sufficient glycogen, the liver synthesises glucose from non-carbohydrate precursors (amino acids and glycerol). this process requires ATP and GTP and involves 11 enzyme-catalysed steps.

Answer 352

this process requires ATP and GTP and involves 11 enzyme-catalysed steps.

Answer 353

-> excess glucose to fatty acids: in the liver, acetyl-CoA from glucose is used to synthesise fatty acids which are incorporated into triglycerides -> triglyceride storage and transport: triglycerides are stored in adipose tissue or transported via VLDL to tissues such as muscles and adipose tissue -> phospholipid synthesis: fatty acids and glycerol are used to produce phospholipids, key components of cell membranes -> cholesterol synthesis: the liver produces cholesterol from acetyl-CoA which is used in cell membranes, for the production of steroid hormones, and to form lipoproteins (e.g. LDL, HDL) -> steroid hormones: cholesterol is a precursor for hormones like cortisol (from adrenal glands), testosterone (from gonads), and others

Answer 354

in the liver, acetyl-CoA from glucose is used to synthesise fatty acids, which are incorporated into triglycerides.

Answer 355

Triglycerides are a type of fat, called lipid , that circulate in your blood. They are the most common type of fat in your body.

Answer 356

triglycerides are stored in adipose tissue or transported via VLDL to tissues such as muscles and adipose tissue

Answer 357

fatty acids and glycerol are used to produce phospholipids, key component of cell membranes

Answer 358

liver produces cholesterol from acetyl-CoA which is used in cell membranes, for the production of steroid hormones, and to form lipoproteins (e.g. LDL, HDL). cholesterol is a precursor for hormones like cortisol (from adrenal glands), testosterone (from gonads) and other steroid hormones)

Answer 359

Cortisol is a hormone produced by the two adrenal glands, which are located on top of each kidney. The pituitary gland in the brain regulates cortisol production.

Answer 360

Acetyl-CoA is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle to be oxidized for energy production.

Answer 361

1. synthesis of non-essential amino acids: the liver synthesises all non-essential amino acids through transamination and other metabolic pathways 2. synthesis of plasma proteins: liver produces important plasma proteins (e.g. albumin- for osmotic pressure and transport/ clotting factors - for blood coagulation) 3. deamination: amino acids are deaminated and amino group is removed; this produces ammonia which is toxic and must be removed 4. energy production and gluconeogenesis: liver uses deaminated amino acids to generate energy or to synthesise glucose (via gluconeogenesis), particularly during periods of fasting. 5. urea cycle: liver converts toxic ammonia into urea through urea cycle which is then excreted by kidneys, preventing ammonia toxicity.

Answer 362

The liver synthesizes all non-essential amino acids through transamination and other metabolic pathways.

Answer 363

The liver produces important plasma proteins, such as albumin (for osmotic pressure and transport) and clotting factors (for blood coagulation).

Answer 364

Amino acids are deaminated, and the amino group is removed. This produces ammonia, which is toxic and must be processed.

Answer 365

The liver uses deaminated amino acids to generate energy or to synthesize glucose (via gluconeogenesis), particularly during periods of fasting.

Answer 366

The liver converts toxic ammonia into urea through the urea cycle, which is then excreted by the kidneys, preventing ammonia toxicity

Answer 367

mature hepatocytes can undergo cell division; maintains number of healthy hepatocytes severe injury leads to activation of liver progenitor stem cells; can differentiate into other liver cell types chronic disease impairs regenerative ability; cirrhosis

Answer 368

Cirrhosis is a condition in which your liver is scarred and permanently damaged. Scar tissue replaces healthy liver tissue and prevents your liver from working normally. As cirrhosis gets worse, your liver begins to fail. chronic disease impairs liver's ability to regenerate which can lead to cirrhosis

Answer 369

liver progenitor stem cells (can differentiate into other liver cell types)

Answer 370

homeostasis - disposal of waste from body - osmoregulation - regulation of blood volume and pressure - regulation of blood pH - producing hormones

Answer 371

1. ureters 2. bladder 3. urethra

Answer 372

the duct by which urine passes from the kidney to the bladder

Answer 373

700-1000ml

Answer 374

urethral sphincter relaxes detrusor contracts

Answer 375

The walls of the bladder are mainly formed by detrusor muscle, which allows the bladder to contract to excrete urine or relax to hold urine. At the inferior end of the bladder, the detrusor muscle is continuous with the internal urethral sphincter.

Answer 376

- posterior wall of abdomen - retroperitoneal - either side of vertebral column - around level of twelfth rib - lift kidney is slightly higher

Answer 377

Having to do with the area outside or behind the peritoneum (the tissue that lines the abdominal wall and covers most of the organs in the abdomen). kidneys= retroperitoneal

Answer 378

- directly from aorta via renal arteries - returned to inferior vena cava via renal veins - receive 20-25% of resting CO (cardiac output)= ~1200ml/min - This large blood supply is necessary for the kidneys' key functions of filtration, waste removal, and maintaining body homeostasis.

Answer 379

The kidneys receive about 20-25% of the resting cardiac output, which is roughly 1,200 mL/min. This large blood supply is necessary for the kidneys' key functions of filtration, waste removal, and maintaining body homeostasis.

Answer 380

The renal capsule is a fibrous outer layer that surrounds the kidney, providing protection and maintaining its shape. It helps shield the kidney from trauma and infection.

Answer 381

The renal cortex is the outer portion of the kidney. It contains renal corpuscles (which include the glomeruli) and parts of the renal tubules. The cortex is where glomerular filtration occurs, beginning the process of urine formation.

Answer 382

The renal medulla is the inner region of the kidney, located beneath the cortex. It is organized into cone-shaped structures called renal pyramids. The medulla plays a key role in the concentration of urine and reabsorption of water and solutes.

Answer 383

The renal papilla is the tip of the renal pyramid. It is where the renal pyramids empty their urine into the minor calyces. The papilla contains openings called papillary ducts through which urine flows from the renal tubules.

Answer 384

The renal sinus is the central cavity of the kidney, and it contains fat as well as blood vessels (like the renal artery, vein, and nerves). This fat helps cushion and protect the kidney. The renal sinus surrounds the renal pelvis, calyces, and other structures.

Answer 385

The renal sinus is the central area of the kidney where various structures, including the renal pelvis, calyces, renal artery, renal vein, and fat, are located. It is essentially the space inside the kidney that holds these structures.

Answer 386

The ureter is a tube that carries urine from the renal pelvis (from the kidneys) to the bladder. The ureters are part of the urinary tract and play a key role in urine transport.

Answer 387

The renal pyramids are cone-shaped structures located in the renal medulla. Each pyramid contains tubules and the collecting ducts that lead to the renal papilla, where urine is collected into the minor calyces. The base of the pyramids faces the renal cortex, and the apex (renal papilla) faces the renal sinus.

Answer 388

The renal vein carries filtered blood away from the kidney. After the blood has been processed by the kidneys, the renal vein returns it to the inferior vena cava, which then carries it back to the heart.

Answer 389

The renal pelvis is a funnel-shaped structure within the renal sinus that collects urine from the major calyces. The renal pelvis then transports the urine into the ureter for excretion.

Answer 390

The renal artery supplies oxygenated blood to the kidneys. It branches off from the abdominal aorta and enters the kidney through the hilum, where it eventually divides into smaller arteries that feed into the renal tissue.

Answer 391

Minor Calyces: These are small, cup-shaped structures that collect urine from the renal papillae of the renal pyramids. Each pyramid drains urine into a minor calyx. Major Calyces: Several minor calyces merge to form a major calyx, which is larger and leads into the renal pelvis. The major calyces collect urine from multiple minor calyces before it moves to the renal pelvis.

Answer 392

Renal Capsule: Protective outer layer of the kidney. Renal Cortex: Outer part of the kidney, where glomerular filtration occurs. Renal Medulla: Inner part of the kidney, containing renal pyramids. Renal Papilla: Tip of the renal pyramid where urine exits into the minor calyx. Fat in Renal Sinus: Cushions and protects the kidney. Renal Sinus: Central space containing the renal pelvis, calyces, blood vessels, and fat. Ureter: Transports urine from the renal pelvis to the bladder. Renal Pyramid: Cone-shaped structures in the renal medulla that contain renal tubules and collecting ducts. Renal Vein: Carries filtered blood away from the kidneys to the inferior vena cava. Renal Pelvis: Funnel-shaped structure that collects urine from the major calyces and drains it into the ureter. Renal Artery: Supplies oxygenated blood to the kidneys. Minor and Major Calyces: Collect urine from the renal papillae and channel it into the renal pelvis.

Answer 393

- functional unit of the kidneys responsible for: -> ultrafiltration of blood -> reabsorption/excretion

Answer 394

~1.3 million

Answer 395

1. renal corpuscle 2. renal tubule

Answer 396

where blood plasma is filtered lies within renal cortex

Answer 397

1. glomerulus 2. bowman's capsule

Answer 398

a network of capillaries that filter blood and allows small molecules to pass through

Answer 399

the double-walled structure that surrounds the glomerulus and collects the filtrate from the blood

Answer 400

blood is filtered in the glomerulus and the resulting filtrate is collected in the Bowman's capsule. larger molecules like proteins and blood cells are retained in the blood, while smaller molecules enter the filtrate.

Answer 401

- renal corpuscle has two capillary beds in series: the glomerulus (for filtration) and the peritubular capillaries (for reabsorption and secretion) - blood enters the glomerulus from the afferent arteriole, then leaves through he efferent arteriole, which is unusual since most organs drain capillaries into venules. - this unique arrangement helps regulate filtration pressure, allowing the kidney to effectively filter blood and maintain body homeostasis.

Answer 402

Bowman's/glomerular capsule is double-walled cup of epithelial cells

Answer 403

inner visceral layer: wraps around endothelial cells of glomerular capillaries outer parietal layer: forms outer wall of capsule *space between 2 layers is capsular space

Answer 404

capsular space

Answer 405

simple squamous epithelium (allows quick filtration)

Answer 406

glomerular filtration

Answer 407

glomerular capsule *glomerular filtrate

Answer 408

renal tubule

Answer 409

water, sodium, glucose and chloride can normally pass through the filtration barrier red blood cells and large proteins cannot normally pass through and are retained in the blood

Answer 410

1. proximal convoluted tubule 2. loop of Henle 3. distal convoluted tubule

Answer 411

within renal cortex

Answer 412

renal medulla

Answer 413

reabsorption secretion

Answer 414

largely responsible for reabsorption of glucose, sodium and other solutes (renal tubule)

Answer 415

counter-current multiplier (renal tubule)

Answer 416

reabsorbs water from filtrate also sodium and choride (renal tubule)

Answer 417

renal tubule is part of the nephron where filtration occurs, and further processing of the filtrate (precursor to urine) takes place.

Answer 418

Distal convoluted tubules of several nephrons empty into one collecting duct. [The collecting ducts then unite into larger structured called papillary ducts. These drain into minor calyces, which collect the urine produced by kidneys before it moves to major calyces and renal pelvis. ]

Answer 419

papillary ducts. [The distal convoluted tubules (DCT) of several nephrons empty into one collecting duct. The collecting ducts then unite into larger structures called papillary ducts.]

Answer 420

These papillary ducts drain into the minor calyces, which collect the urine produced by the kidneys before it moves to the larger renal structures like the major calyces and eventually the renal pelvis.

Answer 421

-> The countercurrent multiplier system helps establish a concentration gradient in the renal medulla, allowing the kidneys to concentrate or dilute urine. -> Active transport in the ascending limb of the loop of Henle pumps ions out of the filtrate, while water is reabsorbed passively in the descending limb. -> The distal convoluted tubule (DCT) and collecting duct can adjust their permeability to water, depending on the presence of ADH, allowing the kidneys to fine-tune water reabsorption and thus produce either concentrated or dilute urine.

Answer 422

The distal convoluted tubule (DCT) and collecting duct can adjust their permeability to water, depending on the presence of ADH, allowing the kidneys to fine-tune water reabsorption and thus produce either concentrated or dilute urine.

Answer 423

Active transport in the ascending limb of the loop of Henle pumps ions out of the filtrate, while water is reabsorbed passively in the descending limb.

Answer 424

the osmolarity (concentration of solutes) of the solution is equal to that of plasma If the kidneys produce isotonic urine (with an osmolarity equal to that of plasma), this means the body is excreting water but maintaining the balance of solutes (like sodium, chloride, etc.) that match the osmolarity of plasma. This can happen when the body is in normal hydration status, and the kidneys do not need to conserve or excrete large amounts of water.

Answer 425

anti-diuretic hormone stimulated insertion of aquaporin channels. increases water permeability. more water reabsorbed, urine more concentrated.

Answer 426

water diuresis (large amounts of dilute urine)

Answer 427

Water diuresis is the process of excreting large volumes of dilute urine. It happens when there is excess water intake or when ADH secretion is suppressed, reducing the kidneys' ability to reabsorb water. This results in urine that has a low osmolarity, often much lower than plasma, allowing the body to eliminate excess water.

Answer 428

vasoconstriction In addition to regulating water retention in the kidneys, ADH (vasopressin) also plays a crucial role in blood pressure regulation through vasoconstriction

Answer 429

hormone’s ability to constrict blood vessels, which helps increase blood pressure.

Answer 430

increase (renin-angiotensin-aldosterone system)

Answer 431

renin-angiotensin-aldosterone system. -> critical mechanism for maintaining blood pressure, fluid balance, and electrolyte homeostasis. -> through a cascade of events starting with renin release and culminating in the actions of angiotensin II, aldosterone, and ADH, the body increases blood pressure by promoting vasoconstriction, water retention, and sodium reabsorption. -> RAAS is vital for homeostasis in situations where the body needs to conserve water, maintain blood pressure, and regulate electrolyte balance, especially during dehydration or low blood volume conditions.

Answer 432

Through a cascade of events starting with renin release and culminating in the actions of angiotensin II, aldosterone, and ADH, the body increases blood pressure by promoting vasoconstriction, water retention, and sodium reabsorption.

Answer 433

can decrease sodium and water excretion can increase angiotensin II formation

Answer 434

increase reabsorption of calcium in Distal Convoluted Tubule (DCT)

Answer 435

arterial natriuretic peptide (ANP); secreted by atrial myocytes in response to distension brain natriuretic peptide (BNP); mainly secreted by ventricles in response to stretch c-type natriuretic peptide (CNP); formed in brain and in vascular endothelium

Answer 436

ANP and BNP: Both are involved in reducing blood volume, lowering blood pressure, and promoting the excretion of sodium and water. These peptides help counteract the effects of RAAS, sympathetic nervous system, and aldosterone, which tend to increase blood volume and pressure. CNP: Primarily contributes to vasodilation and regulation of vascular smooth muscle tone, with a weaker natriuretic effect compared to ANP and BNP

Answer 437

(atrial natriuretic peptide) secreted by atrial myocytes in response to distension

Answer 438

(brain natriuretic peptide) mainly secreted by ventricles in response to stretch

Answer 439

in brain and in vascular endothelium

Answer 440

Vascular tone refers to the degree of constriction experienced by a blood vessel relative to its maximally dilated state

Answer 441

Angiotensin II formation triggers a series of responses aimed at increasing blood pressure and maintaining blood volume: -> Vasoconstriction (increased vascular resistance). -> Aldosterone secretion (sodium and water retention). -> ADH secretion (water retention). -> Sympathetic nervous system activation, which amplifies heart rate and vascular resistance, further raising blood pressure.

Answer 442

Serosa and adventitia are both outermost layers of the gastrointestinal tract, but they differ in their location and composition: serosa covers organs within the peritoneal cavity (intraperitoneal), while adventitia covers organs outside the peritoneum (retroperitoneal)

Answer 443

Brunner's glands are submucosal glands primarily located in the proximal duodenum, responsible for secreting an alkaline fluid containing mucin. This alkaline secretion helps protect the duodenal lining from the acidic stomach contents. They also produce and secrete "enterogastrone," an enteric hormone that inhibits gastric acid secretion