Liver, gallbladder and pancreas Flashcards
Liver location
Thoracic part of the abdomen (medial and deeper to the ribs, dorsal to the sternum) and immediately caudal to the diaphragm in the midline but towards the right side of the abdomen cranial to the stomach. Adjacent to the stomach and duodenum, cranial to the jejunum
Gallbladder location
caudal aspect of the visceral surface of the liver, in a fossa between the quadrate and the right medial lobe
Pancreas location
Thoracic part of the abdomen, dorsally and adjacent to the cranial duodenum, towards the right side of the dorsal abdomen
Liver
The largest gland with exocrine and endocrine functions • Concave caudally, convex cranially • Made of lobes separated by fissures (number and pattern varies across species) • Pedagogic view – 6 lobes in dogs • Connected to the cranial duodenum by the hepatoduodenal ligament (bile duct) • Connected to the stomach by the lesser omentun • Caudate process – kidney impression
Parts of the liver
Left lateral lobe Left medial lobe Quadrate lobe Caudate process Lesser omentum Right lateral lobe Right medial lobe
What does the liver do?
Helps with digestion by producing bile (fat emulsification)
Break down red cells, metabolism of bilirubin and excretion of urobilinogen
Active role in carbohydrate metabolism and storage
Processes nutrients, breaks down fat, creates fat (cholesterol), carbohydrates and proteins
Filtration of blood and content from GIT
Breakdown of GIT toxins and systemic drugs
Immunology role (creates proteins)
Regulation of blood composition (and small role in blood pressure)
Carbohydrate metabolism: glycogenesis, glycogenolysis and gluconeogenesis
• Protein anabolism (transamination and synthesis of essential aminoacids) and catabolism
(deamination and production of ammonia and urea. Synthesis of proteins needed to maintain
oncotic pressure (albumin)
• Haematology and immunologic role: synthesis of plasma proteins (albumin), clotting factors
and immunoglobulins, break down of red cells and synthesis of 50% of the lymph, in young
animals haematopoietic role
• Lipid metabolism: lipogenesis, fatty acid oxidation (break down of fats) and lipoprotein
synthesis (good and bad cholesterol)
• Storage of carbohydrates, vitamins, minerals (iron)
• Secretory (exocrine, digestive) role and excretory role (waste products, bilirubin byproducs,
toxins, drug by products) through bile
Exocrine
relating to or denoting glands which secrete their products through ducts opening on to an epithelium rather than directly into the blood.
Endocrine
relating to or denoting glands which secrete hormones or other products directly into the blood
Excretion
(in living organisms and cells) the process of eliminating or expelling waste matter.
Secretion
a process by which substances are produced and discharged from a cell, gland, or organ for a particular function in the organism or for excretion.
Systemic
Pertaining to or affecting the body as a whole.
Bilirubin
a brownish yellow pigment of bile, secreted by the liver in vertebrates, which gives to solid waste products (feces) their characteristic colour. It is produced in bone marrow cells and in the liver as the end product of red-blood-cell (hemoglobin) breakdown.
Haemoglobin
also spelled haemoglobin, iron-containing protein in the blood of many animals—in the red blood cells (erythrocytes) of vertebrates—that transports oxygen to the tissues. Hemoglobin forms an unstable reversible bond with oxygen.
Lymph
a colourless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the bloodstream.
Glycogenesis
the formation of glycogen from sugar.
Gluconeogenesis
Gluconeogenesis is the formation of new glucose molecules in the body as opposed to glucose that is broken down from the long storage molecule glycogen. It takes place mostly in the liver, though it can also happen in smaller amounts in the kidney and small intestine. Gluconeogenesis is the opposite process of glycolysis, which is the breakdown of glucose molecules into their components.
Glycolysis
the breakdown of glucose by enzymes, releasing energy and pyruvic acid
Lipogenesis
the metabolic formation of fat.
Oncotic pressure (blood)
Oncotic pressure is defined as the osmotic pressure exerted by colloids in solution
Pulmonary circulation
Deoxygenated blood from the heart to the lungs and returns oxygenated blood to the heart
Deoxygenated blood from the right ventricle to the lungs through pulmonary artery
• Pulmonary artery divides into many fine capillaries which wrap around the alveoli (CO2 is exchanged for O2)
• Oxygenated blood returns to the heart via the pulmonary vein
Systemic circulation
Oxygenated blood around the body and returns deoxygenated blood to the heart
Blood with O2 leaves the left ventricle through aorta
• Aorta branches taking blood to various parts of the body
• Exchange happens in the capillaries in the tissues
• Deoxygenated blood returns from the tissues in the veins which drain into the vena cava
Blood supply to the liver
- Main blood supply through hepatic artery, a branch of the aorta artery (“clean oxygenated blood”)
- Also through the hepatic portal vein – “dirty non oxygenated blood” that comes from GIT with all the toxins (but all the nutrients too!)
- Liver “cleans” this blood and uses it too! Returning it to the systemic circulation through the hepatic vein which drains into the vena cava. It is “detoxified” but still deoxygenated.
Immunological role of the liver
- In younger animals – factory of red blood cells (haematopoietic role) including leucocytes (white blood cells)
- In older animals:
- Factory of 80% of the innate immunity proteins
- Storage of macrophages (Kupffer cells)
- Ad hoc storage of monocytes/macrophages (inflammation)
- Storage of natural killers (NK)
Bile and bile ducts
Bile is made of bile acids, cholesterol (formed in the hepatocytes are drained into the canaliculi) and pigments (bilirubin)
• This is the exit route for drug metabolites too, and other toxins
• Bile acids together with other liver enzymes produced in the liver can be used to asses how healthy the liver and the gall bladder are
• Bile is drained into the bile duct
Total protein g/l
Blood protein (sum of albumin + globulin) Albumin is liver marker. Globulins increase during inflammation/infection. Also during dehydration
Albumin g/l
Main blood protein, carrier molecule
Increases during dehydration. Decreases during liver damage or sever haemorrhage
Globulin g/l
Other blood protein, often associated with immune system
Increases during infection/inflammation
ALT IU/l
Liver enzyme, Alanine Transaminase
Enzyme located in the liver tissue. Increases when true liver damage
AST IU/l
Liver enzyme, Aspartate aminotransferase
Enzyme located in the liver tissue. Increases when true liver damage. However, also produced in muscle, so it can increase when muscle trauma or recumbency/myopathies
ALP IU/l
Liver enzyme, Alkaline Phosphatase
Enzyme in the lining of the bile ducts. Increases when bile obstruction or disease. However also produced by the bone and intestine. Liver disease, inflammation of the gall bladder or the ducts (or infection), pancreatic disease or intestinal disease can give increase of this enzyme
GGT IU/l
Liver enzyme, Gamma Glutamyl Transpeptidase
Enzyme in the lining of the bile ducts. Increases when bile obstruction or disease.
Cholesterol mmol/l
Steroid metabolite. Cell membranes, bile, steroid synth
Increases when bile flow is impaired
Bile acids umol/l
Steroid acids found in bile
Inflammation/infection of the bile ducts.
Bilirubin umol/l
Breakdown product of RBCs.
Liver ability to conjugate it is exceeded either due too many red cells are dying or the liver is damaged
Pancreas
Exocrine (digestion) and endocrine gland • In dorsal abdomen, in the mesenterium adjacent to descending duodenum and right lobe • Parts: Left lobe, body and right lobe
Pancreatic exocrine secretions
• Enzymes are secreted into the duodenum through the pancreatic duct into the major duodenal papilla
• Bile duct drains here too
• In dogs and horses there is
an additional duct: accessory duct draining into the minor papilla
AMYLASE : Continues breakdown of carbohydrate started by salivary amylase (in some animals)
• TRYPSINOGEN: Enterokinase (enzyme) in intestinal juices which converts Trypsinogen > TRYPSIN (enzymes) which break down proteins (peptides) into amino acids
• LIPASE: Fats > fatty acids + glycerol
• PEPTIDASES: Polypeptides > Peptides > amino acids
Hydrochloric acid (HCl)
Secreted from Fundus of stomach – parietal cells
Increases pH Kills bacteria
Nutrient that helps with proteins
Pepsinogen
Secreted from Fundus of stomach – parietal cells
HCl breaks it onto pepsin. Protein digestion
Nutrient helps with Proteins
Mucus
Secreted from Globet cells stomach Brunner’s glands of duodenum
Protect – prevents autodigestion Protect and change pH to alkali for SI juices to work
Nutritrients that help with Protection Protection and pH change
Gastrin
From fundus of the stomach
Stimulates production of HCl
Nutrient that helps with HCl
Lipase
From Stomach – very small amount
Pancreas and released onto SI – most of the lipase
Fat digestion
Nutrient that helps with Fat
Rennin (=Chymosin)
From Stomach in young animals
Coagulates milk to help protein digestion in SI
Nutrient that helps with Protein
Bicarbonate
From Fundus of stomach – parietal cells
Activates other enzymes
Nutrient that helps with All macronutrients
Dissacharidase
From SI (villi) – Intestinal juice by Crypts of Lieberhuhn in duodenum and proximal jejunum
Break down disaccharides into simple sugars
Nutrient that helps with Carbohydrates
Enterokinase
From SI (villi) – intestinal juice by Crypts of Lieberhuhn in duodenum and proximal jejunum
Conversion of trypsinogen onto trypsin for protein digestion
Nutrient that helps with Proteins
Aminopeptidase
From SI (villi) – intestinal juice by Crypts of Lieberhuhn in duodenum and proximal jejunum
Breaks down peptides onto amino acids
Nutrient that helps with Proteins
Amylase
From Pancreas, released in duodenum
Breakdown of polysaccharides onto disaccharides
Nutrient that helps with Carbohydrates
Trypsinogen
From pancreas , released in duodenum
Release inactive and activated by enterokinase Protein digestion
Nutrient that helps with Proteins
Peptidases
From Pancreas, released in duodenum
Breakdown of polypeptides
Nutrient that helps with Proteins
Bile
From NO ENZYMES – gallbladder and released in duodenum
Bile salts change pH and help to emulsify fat. Activates lipases Fat emulsification and lipase activation
Nutrient that helps with Fat
Insulin
Secreted by the beta cells in response to a HIGH blood glucose level e.g. after a meal
Glucagon
Secreted by the alpha cells in response to a LOW blood glucose level
Somatostatin
Secreted by the delta cells controls insulin and glucagon via an inhibitory effect
Oral cavity
– lips, tongue, gum, dentition, palate, salivary glands
Oropharynx
palate, pharyngeal walls, lymphoid tissue
Stomach
cardias, fundus and pylorus
Small intestine
– duodenum, jejunum and ileum
Large intestine
caecum, colon, rectum and anus
Summary of the digestive system
Oral cavity – lips, tongue, gum, dentition, palate, salivary glands
• Oropharynx – palate, pharyngeal walls, lymphoid tissue
• Oesophagus
• Stomach – cardias, fundus and pylorus
• Pancreas
• Liver and gallbladder
• Small intestine – duodenum, jejunum and ileum
• Large intestine – caecum, colon, rectum and anus
