Anatomy Exam 2

Primary active transport

When energy is required to move a substance across a membrane, often with the help of carrier proteins against the concentration gradient.

Most common type of active transport

Protein pumps

Active transport energy requirement

Energy from ATP is required for the membrane proteins to transport substances across the membrane.

Sodium Potassium Pump

Transports sodium out of the cell while moving potassium into the cell.

Secondary active transport

A cellular process where molecules are moved across a cell membrane against their concentration gradient by using an established ion gradient.

Phagocytosis

The endocytosis of large particles.

Immune cells that engage in phagocytosis

• Neutrophils

• Macrophages

How does phagocytosis work?

Cells patrol the tissues looking for unwanted matter and phagocytize them and digest them.

Pinocytosis

Brings fluid containing dissolved substances into a cell through membrane vesicles.

Endocytosis

An active cellular transport process where a cell brings in extracellular fluids, macromolecules, and large particles by folding its plasma membrane inward to form a vesicle.

Exocytosis

The active transport process by which cells transport molecules and waste out of the cell, involving intracellular vesicles fusing with the plasma membrane and releasing their contents to the exterior.

Cytosol

Jelly-like substance within the cell, provides the fluid medium necessary for biochemical reaction.

Organelles

One of several different types of membrane-enclosed bodies in the cell, each performing a unique function.

Cytoplasm

The organelles and cytosol combined.

Endoplasmic reticulum

A system of channels that is continuous with the nuclear membrane covering the nucleus and composed of the same lipid bilayer material.

ER function

Provides passages throughout much of the cell that function in transporting, synthesizing, and storing materials.

Ribosome

An organelle that serves as the site of protein synthesis

Rough ER function

Makes proteins destined for the cell membrane of for export from the cell.

Protein path

A protein synthesized within the ribosome and released inside the channel of the rough ER before it is transported within a vesicle for packaging and shipping by the Golgi apparatus.

Smooth ER function

• Synthesizes phospholipids, the main component of biological membranes.

• Synthesizes steroid hormones.

• Sequesters and regulates of the concentration of calcium ions.

• Performs a detoxification role by breaking down certain toxins.

Free ribosomes

• Sites of protein synthesis not attached to the rough Er.

• Made of two separate RNA protein complexes known as the small and large subunits

Free ribosomes function

Produces proteins for intracellular use

Nucleolus

Non-membrane bound structure within the nucleus

Nucleolus function

Site for ribosome synthesis, which involves transcription of rRNA from DNA and its assembly with proteins into ribosomal subunits.

Golgi apparatus

Has two distinct sides with different roles.

Golgi apparatus function

One side receives products in transport vesicles. The products are then modified and released from the opposite side a secretory vesicles.

Secretory vesicle path after Golgi apparatus

Migrates to the cell surface and fuses to the cell membrane for exocytosis.

Mitochondria

• A membranous bean shaped organelle.

• Consists of an outer and inner membrane

Cristae

A highly folded inner membrane

Cellular respiration function

Converts nutrient molecules into ATP which provides usable energy for the cell.

Which organ systems use a ton of ATP?

• The muscular system to sustain muscle contraction

• The nervous system because ATP is needed for sodium potassium ion pumps

ATP

• The main energy currency of the cell, and it is an end product of cellular respiration

• When hydrolyzed it becomes ADP releasing energy

Cytoskeleton

• A group of fibrous proteins that provide structural support for cells.

• Critical for cell motility, cell reproduction, and the transportation of substances within the cell.

Three types of cytoskeleton fibers

• Microtubules

• Microfilaments

• Intermediate filaments

Microtubles

• Play a role in the positioning of the organelles and in cell division.

• Core of cilia

Microfilaments

Thin actin fibers constitute a large component of muscle tissue along with the protein myosin.

Responsible for muscle contraction

Intermediate filaments

• Intermediate in thickness

• Provide mechanical support (maintain cell shape)

• Resist tension - cell-cell junctions

Cilia

Short hair like mobile structures found in large numbers on the surface of certain cells

Cilia structure

A ring of nine outer microtubule doublets surrounds two central singlet microtubules.

Nucleus

The largest of a cell’s organelles

Nucleus function

The control center of the cell because it stores all of the generic instructions for manufacturing proteins.

Nuclear envelope

A membrane surrounding the nucleus made of two adjacent lipid bilayers.

Nuclear pore

A tiny passageway that regulates the passage of materials into and out of the nucleus.

Chromatin

Threads composed of DNA and associated proteins.

DNA

The genetic instructions that are used to build and maintain an organism are arranged in strands of DNA.

Genome

An organism’s complete set of DNA

Gene

A portion of the DNA that contains the code for a specific protein.

DNA structure

• Double-stranded nucleic acid.

• The structural unit is a nucleotide

• Side rails of alternating sugar and phosphate groups

• Genetic code is based on 3 bases forming a triplet

Components of a nucleotide

• A nitrogenous base

• Pentose sugar

• Phosphate group

RNA

• Single-stranded and contain no complementary strand

• Contains a ribose sugar

• Contains uracil instead of thymine

Protein synthesis

The process in which cells make proteins

Stages of protein synthesis

• Transcription

• Translation

Location of protein synthesis

Takes place in the cytoplasm at the ribosome

Transcription

The process that transfers the information from DNA to the mRNA

Transcription process

• A region of DNA unwinds and the two strands separate

• The triplets within the gene are used as the template to transcribe the complementary strand of RNA

Codon

A three-base sequence of mRNA

RNA polymerase

The enzyme responsible for transcription, synthesizing an RNA molecule complementary to a DNA template strand

RNA polymerase process

• Bonds to a gene on the DNA
  Unwinds a small section of the DNA

• Reads the DNA template strand

• Joins RNA nucleotides together to form an RNA strand

• Stops when it reaches a termination sequence

Translation

The process of synthesizing a chain of amino acids called a polypeptide

Ribosomal RNA (rRNA)

• Together with proteins, composes the structure of the ribosome

• When an mRNA molecule is ready to be translated, the two subunits come together and attach to the mRNA

Transfer RNA (tRNA)

Carries the appropriate corresponding amino acids to the ribosome

Two sides of tRNA

• One end is a binding site for a specific amino acid

• The other end is a base sequence (anticodon) that matches the codon on the mRNA specifying the particular amino acid

Types of tissues

• Epithelial

• Connective

• Muscle

• Nervous

Epithelial tissue

The exterior cover of the surfaces of the body, lining of internal cavities and passageways, and makes up certain glands.

Epithelium function

• Provide the body’s first line of protection from physical, chemical, and biological wear and tear

• Act as gatekeepers of the body controlling permeability and allowing selective transfer of materials across a physical barrier

• Many epithelial cells are capable of secretion and release mucous and specific chemical compounds onto their apical surfaces

Simple epithelial tissue

One layer

Stratified epithelial tissue

More than one layer

Simple epithelial tissue examples

• Squamous

• Cuboidal

• Columnar

Stratified epithelial tissue examples

• Stratified squamous

  • Keratinized and non-keratinized (moist)

Simple squamous

Stratified squamous

Simple cuboidal

Stratified cuboidal

Simple columnar epithelium

Stratified columnar epithelium

Pseudostratified columnar

What tissues do squamous cells make up?

The endothelium that lines vessels of the lymphatic and cardiovascular system.

Locations of epithelium where passage of chemical compounds is observed

• Alveoli of the lungs where gases diffuse

• Kidney tubules

• Lining of capillaries (endothelium)

Simple cuboidal epithelium

• The nucleus of the box like cells is round.

• There are active secretions and absorptions of the molecules.

Simple cuboidal makes up the lining of…

Kidney tubules and in the ducts of glands

Simple columnar epithelium

Active in the absorption and secretion of molecules

Simple columnar epithelium makes up the…

lining of sections of the digestive system and parts of the female reproductive tract.

Pseudostratified columnar epithelium line…

the respiratory tract where some cells have cilia

Stratified squamous epithelium function

Protects against physical and chemical wear and tear

Two most common types of stratified epithelium in the human body

• The top layer may be covered with dead cells filled with keratin (keratinized)-skin

• The lining of the esophagus non-keratinized (moist)

Epithelial characteristics

• Cells fit closely together

• Tissue layer has one free surface - the apical surface

• The lower surface (basal) is bound by a basement membrane

• It is avascular and depends on diffusion

• Regenerates

• There is little or no extracellular material present between cells

• Adjoining cells for a specialized intercellular connection called cell junctions

Basement membrane

• All epithelia sit on a basement membrane

• Consists of a basal lamina and reticular lamina

Basal lamina

A mixture of glycoproteins and collagen that provides an attachment sits for the epithelium

Reticular lamina

Secreted by the underlying connective tissue

Transitional epithelium

A specialized type of stratified tissue that changes shape as organs stretch and relax.

Tight junctions

Integral proteins in the cell membrane of adjacent cells fuse together forming an impermeable junction that encircles the cell

Gap junctions

Form intercellular passageway between the membranes of adjacent cells to facilitate the movement of small molecules and ions between the cytoplasm of adjacent cells

Tight junctions function

Helps prevent molecules from passing in the extracellular space between cells.

Gap junctions function

Allow electrical and metabolic coupling of adjacent cells, which coordinates function in large groups of cells.

Desmosomes

• Serve as anchoring junctions. The are scattered like rivets and prevent cell separation.

• Intermediate filaments extend from plaque across the cell to anchor on the opposite side

Plaque

A density on the cytoplasmic side of the membrane

Cadherins

Linker proteins that hold adjacent cells together

Microvilli

Finger like projections of the luminal plasma membrane found in many epithelial cells

What type of cells are microvilli commonly found in

Epithelial cells specialized for absorptive function

Striated or brush border

When microvilli are so numerus and regularly arranged they appear striated