Digestion And Excretion Flashcards
Excretion definition
The process by which metabolic wastes are eliminated
Organs of excretion
Kidneys
Skin (sweat)
Lungs (waste gases)
Kidneys function
-To excrete waste products
-Maintenance of volume and composition of extracellular fluid within narrow physiological limits
Extracellular fluid
Blood(plasma)
Interstitial fluid
Intracellular
Water 67% of the total body water
How do the kidneys perform their function
-stabilising osmolality and volume of extracellular fluid
-Regulating the concentration of extracellular ions
-Removing metabolic wastes and foreign substances
-Maintaining acid base balance
List anatomy of the kidney
-Renal capsule
*smooth transparent membrane
-Renal cortex
*outer payed containing functional kidney tissue
-Renal medulla
*inner layer contains tubular tissue
-Calyces
*minor collecting ducts that combine into the major
*Major
-Renal pelvis
*Expanded area of ureter
-Ureter
-Blood supply
Definition of Digestion
The process by which food is broken down into molecules small enough to be absorbed by the body
Components of the GI tract
Head
-teeth and salivary glands
Oesophagus
Stomach
-corpus, fundus, pylorus
Small intestine
-Duodenum, jejunum, ileum
Accessory organs
- liver/gall bladder
- Pancreas
Large intestine
- caecum, proximal/transverse/distal colon, rectum
Definition of egestion
Undigested waste material that’s eliminated
List salivary glands
-parotid = serous
-mandibular, Sublingual, buccal= mixed mucous and serous
-zygomatic = mucous (carnivores only)
Simple stomach animal
-Mucous aid food passage
-PH neutral to allow action of amylase
Complex stomach animals (ruminants)
-mainly serous to give optimum conditions for fermentation
-PH alkaline to buffer forestomach
-copious secretions
Components of saliva
-Mucin
-Amylase (omnivore/horse/ruminant)
-Bicarbonate
-Phosphate (ruminants)
-Lysozyme
-Protein binding tannins (leaf and bud eaters)
-Urea (ruminants)
Secretion of saliva in non ruminants
-isotonic with blood
-at low flow rates becomes hypotonic
-at high flow rates remains isotonic
Secretion of saliva in ruminants
-secretion always isotonic
-low flow rates po4 dominates
-high flow rates HCO3 dominates
Composition of fluid in the abdomen
-mucus
-enzymes for chemical breakdown of food
-ions and pH appropriate for digestive enzymes
Enzymes that break down carbohydrates and where are they secreted
Amylase, disaccharidases
-saliva, Pancreas, intestinal mucosal surface
Enzymes that break down proteins and where are they secreted
Pepsin, trypsin, peptidases
-glands of stomach, Pancreas, intestinal mucosal surface
Enzymes that break down fats and where are they secreted
Lipase, phospholipase
-Pancreas, intestinal mucosal surface
3 main functions of the kidney
Filtration
- Glomerulus
Reabsorption
- Tubules
Secretion
- Tubules
Two main parts of the Nephron
- Glomerulus
-Tubular System
What does the Glomerulus consist of
- Afferent arteriole
(bringing blood too) - parallel capillaries with interconnections located within the bowman’s capsule
- Efferent arteriole
- peritubular capillaries
(form a network to take away he products of reabsorbtion)
What does the tubular tissue consist of
- Bowman’s space
-proximal tubule
-loop of henle
- distal tubule
-collecting duct
