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= Cell Biology Laboratory 3: Cellular Identification =

Liver
Lobule: a roughly hexagonal shape with portal triads, at the vertices and a central vein in the middle.

Hepatocytes: nuclei are round, with one or two prominent nucleoli. Involved in synthesis of proteins

and lipids. Contain a large amount of smooth & rough endoplasmic reticulum

Kidney
The kidney is responsible for the disposal of nitrogenous waste and liver enzyme by-products.

It also plays a key role in pH balance, ion balance, and water balance within the body.

The kidney filters blood through the nephron which consists of the glomerulus, bowman’s

capsule, proximal convoluted tubule, descending loop of Henle,

ascending loop of Henle, and the distal convoluted tubule.

Bone (Ground)
Compact bone (cortical) serves a mechanical bone, this is the area to which ligaments and tendons

attach. Trabecular bone (cancellous) is mainly for metabolic function, it is located in between layers

of compact bone and is thin and porous. located within it is bone marrow.

Intestine
The intestine is integral in absorbing the nutrients we get from food. The intestines run from the

stomach all the way to the anus. For the histology of the intestines, the intestines are made up

of  the mucosa, submucosa, the muscularis, and the serosa. The mucosa is the innermost layer

of the intestines. The next layer is the submucosa, then the muscularis that wraps around the

submucosa. It wraps it in many layers of smooth muscle tissue that moves the intestine.

Smooth Muscle
Smooth muscles form most of the digestive tract, starting from the middle portion of the esophagus

to the internal sphincter of the anus. Smooth muscles are specialized for slow and steady

contractions of low force. Also these muscles are non-striated. Smooth muscles are naturally

contractile, and the autonomic nervous system, hormones and metabolites can influence their

contractions. Therefore, since smooth muscles are not under conscious control, they are

involuntary muscles.

Cardiac Muscle
Cardiac muscle is very specialized muscle tissue that evolved to pump blood throughout the body.

Cardiac muscle is made up of many interlocking cardiac muscle cells/fibers that give the tissue

its properties. Each cardiac muscle fiber contains a single nucleus and is striated/striped.

Cardiac muscle cells have a branched shape so that each cell is always touching 3 or 4 other

cardiac cells. All the cardiac muscle cells in the heart form a network that is all connected

Skeletal Muscle
Skeletal muscle is responsible for the movement of the skeleton, but is also found in organs

such as the globe of the eye and the tongue. It is a voluntary muscle. Skeletal muscle is

specialized for rapid and forceful contraction of short duration.Skeletal muscles are divided

into two muscle fiber types:

Slow-twitch (type I) muscle fibers

Fast-twitch (type II) muscle fibers

Microscopic Anatomy
Receiving blood from the terminal branches of the hepatic artery and portal vein are the sinusoids. These low pressure vascular channels are located at the periphery lobules, the blood is delivered into the central veins. Sinusoids are lined with endothelial cells and are flanked by plates of hepatocytes. Another important feature of the sinusoids is that they house many Kupferr cells which are a type of fixed macrophage. They play a large role in the mononuclear phagocytic system and are important to both the hepatic system and systemic response to pathogens. They are critical mediators to both liver injury and repair. 80% of the livers mass is due to hepatocytes. These are the key functional cells of the liver and perform a different number of metabolic, endocrine, and secretory functions. They are polygonal in shape and connect with sinusoids or neighbouring hepatocytes. The nuclei of the hepatocyte is distinctly round with one or two prominent nucleoli. Due to their involvement in protein and lipid synthesis, they contain a large quantity of smooth and rough endoplasmic reticulum.

Portal Triad
The portal triad is a combination of three major tubes. Branches of the hepatic artery which carry oxygenated blood to the hepatocytes, branches of the portal artery carry blood rich in nutrients coming from the small intestine and lastly, the bile duct transfers the bile products away from the hepatocytes and to larger ducts and gall bladder. Due to the large size of the hepatic venule compared to the smaller hepatic artery, a majority of the blood within the liver will be poorly oxygenated.