Physiology of the Digestive System Flashcards
What are the two processes of the GI tract?
- Digestion
2. Absorption
Digestion is the breakdown of large, ____ food particles into small, ____ food particles
Insoluble; Soluble
Mechanical breakdown involves
Mastication (chewing) in the mouth
Motility (movement) such as mixing and propulsion
Motility (movement) such as mixing and propulsion including
Peristalsis in the entire gut
Churning in the stomach
Segmentation in the small intestine
Chemical breakdown (hydrolysis) using ____ to split large molecules into small molecules (the product of digestion
Enzymes
Enzymes may be secreted by the
Stomach
Pancreas
Enzymes may be bound to _______; involved in membrane (contact) digestion
Intestinal cell membranes
Carbohydrate digestion Is accomplished mainly by carbohydrases in the
(a) Saliva, such as salivary amylase
(b) Intestinal juice, such as maltase
(c) Pancreatic juice, such as pancreatic amylase
Carbohydrate digestion Is also accomplished by carbohydrases in intestinal juice including
(a) Amylase
(b) Sucrase
(c) Lactase
Carbohydrate digestion Produces
(a) 80% Glucose
(b) Fructose
(c) Galactose
Fructose changed to ____ in intestinal epithelial cells
Glucose
_____ changed to glucose in liver cells
Galactose
Almost all the carbohydrates in the blood are in the form of ____
Glucose
Lipid digestion mainly by lipases in
pancreatic juice
Lipid digestion also by lipases in
(a) gastric juice
(b) intestinal juice
Protein digestion Is accomplished mainly by proteases in
(a) Gastric juice
(b) Pancreatic juice
Protein digestion Is also accomplished by ____ in intestinal juice such as enterokinase
Proteases
Protein digestion Requires
hydrochloric acid (HCl)
HCl functions to
[1] Splits large proteins
[2] Activates pepsinogen to pepsin
[3] Kill ingested microorganisms
HCl is neutralized by ______ in small intestine
bicarbonate ions
____ is secreted by all subdivisions of the GI tract
Mucus
Regulation involves endocrine and neural control of two processes The two processes are
(1) Motility
(2) Secretion
Endocrine control involves hormones acting on target tissues The endocrine gland cells may be in an ____ or within the wall of the GI tract
accessory organ
Endocrine control involves hormones acting on target tissues The target organs include the ____ and the accessory organs
GItract
Nervous control involves two different reflexes
(1) Central NS reflexes involve sensory transmission to the CNS and motor transmission to the organs of the digestive system by the PNS (vagus n)
(2) Local NS reflexes involve sensory and motor transmission within the wall of the GI tract
The second major process in the physiology of the digestive system is ____ by active and passive processes
absorption
Absorption is the transport of digested food from the_____ of the GI tract into the body
lumen
Absorption is the transport of digested food from the lumen of the GI tract into the body Most occurs in
small intestine
Absorption is the transport of digested food from the lumen of the GI tract into the body It requires increased
internal surface area
Active processes of absorption include Active transport of
(a) Na+
(b) Ca++
(c) Many other ions
Active processes of absorption include Carrier-mediated transport of A complex process of lipid absorption Lipid digestion leads mainly to
(a) Most monosaccharides (especially glucose)
(b) Amino acids
Active processes of absorption include
[1] Monoglycerides
[2] Fatty acids
[3] Cholesterol
[4] Phospholipids
[5] Glycerol which is
[a] Water soluble
[b] Absorbed easier
Passive processes of absorption include
(1) Osmosis, the absorption of water
(2) Diffusion of some ions such as
(a) K+
(b) Cl-
