Introduction to optometry foundation year at city university of london
Introductory biological sciences module
Lesson 18 about the liver. Everything you need to know about the liver in the course.
Liver
Second largest organ in the human body
constitutes only 2-3% of the body mass
Accounts for 20-30% of the total oxygen
consumption
2 lobes
Important in intermediary metabolism and in the
detoxification and elimination of toxic substances
Filters 1.4L blood every minute
Functions of the liver
- maintains the body's chemical and
metabolic homeostasis >500 functions
1. Uptakes nutrients from digestive tract into the portal vein
a. Synthesis, storage, interconversion, degradation of metabolites (metabolism),
temporary nutrient storage (glucose-glycogen)
b. Regulated supply of energy-rich intermediates and building blocks for
biosynthesis reactions
2. Vitamin storage and maintains iron reserves
3. Produces coagulation factors
4. Detoxification - removes toxins from the blood
a. The excretion of substances with the bile, urine and faeces
5. Bile production
6. Role of Kupffer cells (macrophages)
Liver anatomy
2 lobes- falciform ligament separates the
lobes and holds the liver to the abdominal
wall and diaphragm surface
Each lobe contains lobules
Each lobules is comprised of hepatocytes
Connective tissue support: thin connective
tissue capsule
Interlobular spaces - support
blood vessels and bile ducts
reticular fibres- collagen III- lots
of proteoglycan (flexibility)
Pipework
Blood in through the portal vein (hepatic vein)
and the hepatic artery (from the spleen,
pancreas and gallbladder)
Blood out through central vein
Blood from portal vein and hepatic artery mix
in the hepatic sinusoids
, Bile is secreted by hepatocytes and leaves through the
bile ducts
Dual blood supply to liver
1. Oxygen rich blood from the hepatic artery (branch
off the abdominal aorta) 25% of blood supply
2. Nutrient rich, oxygen poor blood from the portal
vein (portal vein carries blood that has just been
through the gastrointestinal tract) 75% of blood
supply
Hepatocytes (type of epithelial cell) and hepatic sinusoids
- Hepatocytes have microvilli to increase surface area
- Adjacent cells have tight junctions (tightly joined)
- Disse’s space separates the hepatic sinusoid vasculature from
hepatocytes
- Sinusoids are fenestrated capillaries that allows plasma
through but not erythrocytes
- Macromolecules from digestion are in plasma
- bile canaliculi runs between hepatocytes
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