Lecture 26 - The Liver ✅

The “metabolic bridge”

Liver

The link between nutrient absorption and nutrient regulation

The liver

Why is the liver called “The Anatomical Bridge”

Connecting digestion to circulation via the hepatic portal system

Why is the liver called “The Excretory Bridge”

Excretion of lipid-soluble waste (through bile) and urea (to kidneys)

Why is the liver called “The Regulatory Bridge”

The liver is the primary effector for metabolic hormones

Where does the liver export produced bile?

Duodenum

Largest gland in the body

Liver

Why is the liver called a gland?

Makes hormones the body needs

Porta hepatis

Gate to the liver

Number of lobules in each lobe of the liver

1000s

Carries nutrient rich blood from the intestines

Portal vein

Carries oxygenated blood from the abdominal aorta

Hepatic artery

Drains bile

Bile duct

What is this?

Lobule

What is this?

Lobule

From what artery does the colon receive blood?

Superior and inferior mesenteric arteries

From which artery do the small intestines receive blood

Superior mesenteric arteries

Which arteries supply the pancreas?

Superior mesenteric and celiac arteries

Which artery supplies the spleen and stomach?

Celiac artery

The stomach, spleen, pancreas, small intestines, and colon all supply the liver with blood through which vein?

Portal vein

Which artery supplies the liver?

Hepatic artery

What do the hepatic veins (from the liver) supply?

Inferior vena cava

A?

Biotransformation

B?

Storage

C?

Synthesis

The body’s primary metabolic hub

The liver

Converts glucose to glycogen for storage

Glycogenesis (glyco=glucose, genesis=first)

Converts glycogen to glucose for release

Glycogenolysis (lysis=release)

Creates glucose from amino acids or lipids

Gluconeogenesis (neo=new)

High blood sugar promotes the release of what hormone?

Insulin

What does the pancreas release to stimulate glycogen breakdown

Glucagon

Low blood sugar stimulates the release of what hormone?

Glucagon

What does the pancreas release to stimulate glucose uptake in tissue cells from blood?

Insulin

What does the pancreas release to stimulate glycogen formation?

Insulin

What does the liver perform as blood passes through

“Quality control”

Three forms of “quality control” performed by the liver

Plasma protein synthesis, removal of hormones/toxins, and waste conversion

What does the liver produce via plasma protein synthesis?

Albumin and clotting factors

Protein crucial for osmotic pressure

Albumin

How does the liver perform the removal of hormones/toxins:

Breaking down circulating hormones and neutralizing drugs or environmental toxins

What does the liver convert ammonia (from protein breakdown) into?

Urea

After the liver converts ammonia into urea, where is it sent back to for excretion?

The kidneys

Which organ synthesizes and secretes bile

The liver

Where is bile from the liver stored?

Gallbladder

Essential for the emulsification of lipids in the small intestine

Bile salts

Transforming large fat globules into small droplets that pancreatic lipases can actually digest

Emulsification

Where in the gallbladder is bile created?

Bile canaliculi

What cells in the gallbladder produce bile?

Hepatocytes

What vitamins and minerals are stored in the liver for the long-term?

Fat-soluble vitamins, Vitamin B12, and Minerals

Which vitamins are have long term storage in the liver?

A, D, E, and K

Large reserves of which vitamin are kept in the liver to support red blood cell production?

B12

What two minerals are stored for the long-term in the liver?

Iron and copper

What is iron stored as in the liver?

Ferritin

Specialized macrophages in the sinusoids are first line of defense for the blood coming from the digestive tract

Kupffer cells

Physically engulf pathogens, cell debris, and aged red blood cells before they can reach the systemic circulation

Kupffer cells

What activates kupffer cells to release cytokines & chemokines, causing inflammatory response?

Injured hepatocytes

What are the purple cells?

Kupffer cells

An essential endocrine gland, producing key hormones and proteins that regulate blood pressure, clotting, and growth

Liver

A protein converted to angiotensin, acts to raise blood pressure and regulate blood volume

Angiotensinogen

A glycoprotein hormone that stimulates bone marrow cells to produce platelets from megakaryocytes (essential for blood clotting)

Thrombopoietin (TPO)

Produced in response to growth hormone, promotes cell growth, differentiation, and metabolism

Insulin-like Growth Factor 1 (IGF-1)

A peptide hormone that plays a crucial role in iron homeostasis by regulating iron absorption and utilization

Hepcidin

Angiotensinogen, thrombopoietin (TPO), insulin-like growth factor 1 (IGF-1), hepcidin are hormones produced by what organ?

Liver

A?

Thrombopoietin

Plays a critical role in metabolizing, breaking down, and regulating levels of other hormones (e.g., estrogen, progesterone, thyroid hormone)

Liver

How does the liver transport estrogen?

Through bile