Liver, gallbladder and pancreas Flashcards by Beth Finlay

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

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Gallbladder location

caudal aspect of the visceral surface of the liver, in a fossa between the quadrate and the right medial lobe

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Pancreas location

Thoracic part of the abdomen, dorsally and adjacent to the cranial duodenum, towards the right side of the dorsal abdomen

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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

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Parts of the liver

Left lateral lobe
Left medial lobe Quadrate lobe
Caudate process
Lesser omentum
Right lateral lobe Right medial lobe

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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

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Exocrine

relating to or denoting glands which secrete their products through ducts opening on to an epithelium rather than directly into the blood.

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Endocrine

relating to or denoting glands which secrete hormones or other products directly into the blood

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Excretion

(in living organisms and cells) the process of eliminating or expelling waste matter.

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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.

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Systemic

Pertaining to or affecting the body as a whole.

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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.

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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.

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Lymph

a colourless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the bloodstream.

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Glycogenesis

the formation of glycogen from sugar.

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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.

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Glycolysis

the breakdown of glucose by enzymes, releasing energy and pyruvic acid

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Lipogenesis

the metabolic formation of fat.

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Oncotic pressure (blood)

Oncotic pressure is defined as the osmotic pressure exerted by colloids in solution

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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

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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

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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.

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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)

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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