Gastro-intestinal And Urinary System

Question 1

DIGESTION - process

Answer 1

1. Ingestion = eating or drinking
2. Secretion = Gl tract secretes 7 I of water, acids, buffers, and enzymes
3. Mixing & propulsion = smooth muscle in GI tract mix and move food forward = motility
4. Digestion = Mechanical (smooth muscle movements) and Chemical (break down of molecules) processes break down food into small molecules
5. Absorption = digestion products absorbed by epithelial cells lining the GI tract
6. Defication = wastes, indigestable substances, bacteria, and materials not absorbed leave the body

Question 2

DIGESTION - regulation

Answer 2

• Stimulation of receptors like chemoreceptors or stretchreceptors
→ chemoreceptors register taste/smell → sensory (somatic) system → parasympathetic nerve impulses → smooth muscle contraction and hormone gastrin → secretion of gastric juice → prepares stomach for food (long reflex)
→ stretchreceptors register pressure against wall → enteric nervous system → same effect (short reflex)
• Fear and anxiety → sympathetic nerve impulses → suppress contraction and gastric juice

Question 3

ORAL CAVITY - glands and function

Answer 3

• Salivary glands: Located outside oral cavity; 3 types producing different types of saliva; controlled by parasympathetic normally and sympathetic during stress
• Functions:
→ Chemical digestion: Saliva (water+ solutes) moisturizes and lubricates food, and consists enzyme amylase which starts breakdown of startches
→ Mechanical digestion: teeth divide food apart, tongue (skeletal muscle) mixes food with saliva

Question 4

Swallowing process

Answer 4

• Voluntary stage: tongue moves upward and backwards → forces food backwards in mouth
• Involuntary pharyngeal stage: swallow → pharynx → larynx closes by epiglottis and breathing stops → upper esophageal sphincter relaxes → food into esophagus
• Involuntary esophageal stage: food moves through esophagus via peristalsis (= movements of muscles) → lower esophageal sphinter relaxes → food into stomach

Question 5

STOMACH

Answer 5

• Structure: Cardia = surrounds lower esophgeal sphincter; Fundus = upper left to cardia, stores food; Body = below fundus and central part; pylorus = connects stomach to duodenum with pryloric sphincter between
• Secretion: gastric juice (G-cells making gastrin); Hydrocloric acid → low pH → amylase stop working; pepsinogen → pepsin when contacting HCI; mucus → protect walls
• Mechanical digestion: propulsion → smooth muscle mixes food and moves it
• Chemical digestion: pepsin break down protein

Question 6

PANCREAS

Answer 6

• Parasympathetic impulses - vagus nerve (10) also secretin and CCK (hormones) → secretion of pancreatic enzymes → pancreatic duct → duodenum
• amylase = digest carbonhydrates
• lipase = lipid digestion
• proteases and peptidases = protein digestion (inactive → active in duodenum)
• bicarbonate ions = inactivates pepsin

Question 7

LIVER

Answer 7

• Synthesizes plasma protein, cholesterol, glycogen, and bile
• Stores fat-soluble vitamins, iron, and glycogen
• Detoxification
• Blood reservoir

Question 8

GALL BLADDER

Answer 8

• Hanging from liver
• Stores, concentrates, and secretes bile
• Bile = bile salts → break down fat

Question 9

INTESTINES

Answer 9

• Duodenum, jejunum, ileum, colon, and rectum
• Gastrocolic reflex: intestines motility is stimulated when food enters stomach

Question 10

SMALL INTESTINE - secretion

Answer 10

• Digestive enzymes
• Mucus
• Intestinal juice → aids absorption
• CCK and Secretin

Question 11

SMALL INTESTINE - Digestion

Answer 11

• Mechanical: Peristalsis → food pushes forward; Segmentations → mix food with juices → food particles to mucosa for absorption
• Chemical: Pancreatic juice and bile

Question 12

SMALL INTESTINE - Absorption

Answer 12

• Most absorption in jejunum and ileum
• Nutrients, water, ions, and vitamines
• Wall cells has microvilli and tissue folded → larger area for absorption
• Diffusion, osmosis, active transport

Question 13

THE COLON

Answer 13

• Content pushed forward by peristalsis and mass peristalsis
• Absorb vitamin, water, and ions (some)
• Forms feces as result of absorption

Question 14

THE RECTUM

Answer 14

• Stores feces
• Feces in rectum → stimulate stretch receptors → initiate defication reflex
→ to spinal cord → parasympathetic impulse → opens internal sphincter (involuntary)
→ to motor cortex → external sphincter opens voluntary → defication completed

Question 15

KIDNEYS

Answer 15

• Produces EPO
• Release renin = enzyme regulating blood volume and pressure: renin → RAAS
• Release calcitriol
• ADH = volume of urine: increased → less urine

Question 16

NEPHRON

Answer 16

• Glomerular filtration = first step of urine production: blood pressure → water+solutes filtrate out → glomerular capsule → proximal tubular (primary urine)
• Tubular reabsorption = in loop of Henle: water and useful solutes → peritubular capillaries → blood stream
• Tubular secretion = in loop of Henle: wastes, drugs, and excess ion get secreted from peritubular capiIlaries → collecting duct → renal pelvis → urine

Question 17

MICTURITION

Answer 17

Increased urine volume in bladder → pressure increases → stretch receptors transmit nerve impulses → spinal cord
→ parasympathetic nerve impulse → contraction of detrusor muscle and relaxation of internal urethral sphincter (involuntary)
→ to brain → motoric innervation → relaxation of external urethral sphincter → micturition (voluntary to a certain degree)

Question 18

Regulation of pH

Answer 18

• Buffert system with carbonic acid and bicarbonate ions
• Low pH: bicarbonate bind H+ and H+ out with urine, AND H+ decrease when more CO2 is exhaled (increased ventilation)
• High pH: Carbonic acid splits into H+ AND decreased ventelation increases H+