EUKA N PROKA CELL L1 PT. 2

• Animal cells

  • no cell wall
  • no chloroplast
  • have many small vacuoles
  • nucleus is present at the center of the cell
  • contains lysosomes
  • contains centrioles near the nucleus
  • irregular in shape
• Plant cells

  • contains cell wall
  • contains chloroplast
  • contains a large central vacuole
  • have definite shape
  • nucleus is pushed to one side of the cell
  • cell wall maintains the structure of the plant cells
• both animal and plant cells have:

  • mitochondria
  • cell membrane
  • cytoplasm
  • endomembrane system
  • ribosomes
  • nucleus
• cell modification that lead to adaptation

  kinds of cell modification:

  • apical modification (top) - cell modification is found on top surface of the cell
  • basal modification (bottom) - cell modification is found on the bottom surface of the cell
  • lateral modification (sides) - cell modification is found on the sides of the cell
• Apical Modification

  Microvilli

  • also called brush/strained border
  • finger-like cytoplasmic extensions of the apical surface which increase surface area for absorption
  • numerous, often regularly arranged, and found in absorptive epithelia
• Apical Modification

  Stereocilia

  • long microvilli that function in increasing absorption
  • non-motile
  • found in sensory cells in ear and male reproductive tract
  • does not have the true characteristics of the true cilia or flagella
• Apical Modification

  Cilia

  • motile, function in movement
  • beats in a coordinated rhythmical wave-like movement of materials over the surface
  • appears as short hair-like structures or projections
  • each cilium is connected to a basal body and extends from the free surface
  • core is composed of microtubules arranged in a specific manner
  • can be found in the lining of the trachea (windpipe) or in the Fallopian tube
• Apical Modification

  Flagella

  • are also concerned with movement
  • same axial structure with cilia but much longer
  • present in tail of the spermatozoa
• Basal Modification

  Basal Infoldings

  • often found in epithelium that are known to transport fluid (kidney)
  • will often see mitochondria in the basal infoldings, suggests that active transport is occurring
  • very important in epithelial polarization and stability
  • support the epithelium and also functions as a passive molecular sieve or ultrafilter
  • if basal lamina is destroyed (trauma, infections, burns) the epithelium will not be repaired but substituted with a scar (connective tissue)
• Basal Modification

  Hemidesmosome

  • protein filaments interlock with filaments of the adjacent cell which forms a dense intermediate line between the cells
  • found beneath the zonula adherens
  • cytoplasmic face is connected to microfilaments extending into the cytoplasm
• Lateral Modification

  Light junctions (Zonula occludens)

  • a band near the apical surface forms a seal, appearing to be fused
  • there is 15-20 mm space between epithelium cells
  • tight junction occludes/separates the compartments
• Lateral Modification

  Adhering junction (Zonula adherens)

  • the actin filaments which make up zonula adherens maintain integrity of the cell to better bind
  • found just beneath the tight junction
  • cytoplasmic face is linked to the actin cytoskeleton
• Lateral Modification

  Desmosome (Maculs Adherens)

  • protein filaments interlock with filaments of the adjacent cell which forms a dense intermediate line between the cells
  • help to resist shearing forces and are found in simple and stratified squamous epithelium
• Lateral Modification

  Gap Junctions

  • connexons of one membrane aligns with connexion of adjacent membrane so that hydrophilic material can be transported
  • important in cell communication
  • adjacent cells are 2-3cm apart
• Specialized Modification

  Nerve cells or neurons are very specialized cells of the nervous system. Since an electrical signal needs to travel relatively long distances to parts of the body, nerve cells have specialized structures called dendrites, which received an electrical signal from another neuron, and axons, which transmit an electrical signal to another neuron.
• Muscle cells are made up of primarily of a pair of special proteins called actin and myosin which allows the muscle to contract
• Red blood cells (RBC) are anucleate, and thus are produced from bone marrow, but contain large amounts of hemoglobin to transport oxygen throughout the body.
• Sperm cells are haploid and contain a flagellum in order to swim through the vagina
• Plant cells have large amounts of organelle chloroplast, which allows the cell to undergo photosynthesis. Plant cells are also covered with cell wall.
• A tissue is a group of cells connected to each other that collectively perform similar functions in an organism. All contents of the body including structures and various organs are made of tissue
• Four basic types of animal tissue:

  • epithelial tissues
  • muscle tissues
  • nervous tissues
  • connective tissues
• Epithelial tissue - made up of tightly packed cells layer together, epithelial tissues line the body surface. Their functions include protection, absorption, and secretion. Epithelial tissues can be found in the lining of the mouth and nose, the digestive system lining, and the skin.
• Types of Epithelial Tissue

  • Squamous epithelium
  • Cuboidal epithelium
  • Columnar epithelium tissue
  • Pseudostratified columnar epithelium
  • Ciliated epithelium tissue
  • Transitional epithelium
• Squamous epithelium - closely packed with one another, these are thin and flat cells that mostly like the esophagus, blood vessels, alveoli, and the inner cavities of the mouth. The squamous epithelium tissue lends protection against mechanical injuries while also blocking any sort of germs from entering
• Cuboidal epithelium tissue - these are cuboidal in shape, hence rightfully deceiving their name. Found in kidney tubules, salivary glands, and sweat glands, the functions of the cuboidal epithelium tissue are secretion, protection, and absorption.
• Columnar epithelium tissue - mostly with column-like or pillar-like cells these can be found in the intestine and lining of the stomach. Important functions of the columnar epithelium tissue include secretion and absorption.
• Pseudostratified columnar epithelium - are tissues formed by a single layer of cells that appear made from multiple layers, especially when seen in cross-section. The nuclei of these epithelial cells are at different levels leading to the illusion of being stratified.
• Ciliated epithelium tissue - the columnar epithelium tissue often have cilia; this is when they come to be known as ciliated epithelium tissues. These can be found in kidney tubules, the respiratory tract, and the lining of the trachea. Their function is to help in the movement of material in a given direction.
• Transitional epithelium - is a layer of cells that forms the mucosal lining of your ureters, a portion of your urethra, and your urinary bladder. These cells are called transitional because they can undergo a change in their shape and structure.
• Muscle tissues - are specialized tissues found in animals, responsible for applying force to various parts of the body by using the method of contraction. Thin and elongated cells called muscle fibers make up the muscle tissues.
• The structure of muscle tissues contains three distinct elements - the cytoplasm in the muscle fibers, called the sarcoplasm, a membrane network called the sarcoplasmic reticulum, and the surrounding membrane of the muscle fibers known as the sarcolemma.
• Types of muscle tissues

  • smooth muscle tissue
  • skeletal muscle tissue
  • cardiac muscle tissue
• skeletal muscle tissue

  • found attached to the bone and helps in body movement
  • fibers : striated, tubular, and multi nucleated
  • voluntary
  • usually attached to skeleton
• smooth muscle tissue

  • found in the inner lining of organs
  • fibers : non-striated, spindle-shaped, and uninucleated
  • involuntary
  • usually covering wall of internal organs
  • arterial blood flow
• cardiac muscle tissue

  • is found in the heart. These tissues help in changing the size of a cell
  • fibers : striated, branched, and uninucleated
  • involuntary
  • only covering walls of the heart
  • pump heart or blood
• Connective tissue - made up of various cells that are involved in lending support to the body, connective tissues are namely the fat, bone, blood, and cartilage in an animal body.
• Types of connective tissues

  • Areolar connective tissue
  • Adipose tissue
  • bones tissue
  • cartilage
  • blood
• Areolar connective tissue - these are found under the skin, surrounding nerves, and blood vessels. Their function is to repair tissues and provide support
• Adipose tissue - also known as body fat, is a connective tissue that extends throughout the body. It's found under the skin (subcutaneous fat), between the organs (visceral fat), and even in the inner cavities of bones (bone marrow adipose tissue). Body fat is primarily known for storing and releasing energy and providing insulation.
• Bones tissue - these form the skeletal structure of the body and have the characteristic of being rich in calcium and collagen fibers. They protect the body and are the location of blood cell production.