Embyrology

Tissue and Cell Types

Overview of Meiosis

Overview of Meiosis

Meiosis is a two-part cell division process in organisms that sexually reproduce. Meiosis produces gametes with one half the number of chromosomes as the parent cell.

In some respects, meiosis is very similar to the process of mitosis, yet it is also fundamentally different.

The two stages of meiosis are meiosis I and meiosis II. At the end of the meiotic process, four daughter cells are produced. Each of the resulting daughter cells has one half of the number of chromosomes as the parent cell.

Before a dividing cell enters meiosis, it undergoes a period of growth called interphase.

During interphase the cell increases in mass, synthesizes DNA and proteins, and duplicates its chromosomes in preparation for cell division.

Meiosis I

Meiosis I encompasses four stages:

• Prophase I
  
• Metaphase I
  
• Anaphase I
  
• Telophase I
  

In most cases, at the end of meiosis I, two daughter cells are produced.

Meiosis II

Meiosis II encompasses four stages:

• Prophase II
  
• Metaphase II
  
• Anaphase II
  
• Telophase II
  

At the end of meiosis II, four daughter cells are produced. Each of these resulting daughter cells is haploid 

Before a dividing cell enters meiosis, it undergoes a period of growth called interphase.

Interphase:

• G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.
• S phase: The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.
• G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.
• In the latter part of interphase, the cell still has nucleoli present.
• The nucleus is bounded by a nuclear envelope and the cell's chromosomes have duplicated but are in the form of chromatin.
• In animal cells, two pair of centrioles formed from the replication of one pair are located outside of the nucleus.

Overview of Mitosis

Overview of Mitosis

Cell division is an elegant process that enables organisms to grow and reproduce. Through a sequence of steps, the replicated genetic material in a parent cell is equally distributed to two daughter cells. While there are some subtle differences, mitosis is remarkably similar across organisms.

Before a dividing cell enters mitosis, it undergoes a period of growth called interphase. Interphase is the "holding" stage or the stage between two successive cell divisions. In this stage, the cell replicates its genetic material and organelles in preparation for division.

Mitosis is composed of several stages:

• Prophase
  
• Metaphase
  
• Anaphase
  
• Telophase
  

Let's briefly look at some important events in each step in the process.

Prophase

In prophase, the chromatin condenses into discrete chromosomes. The nuclear envelope breaks down and spindles form at opposite "poles" of the cell.

Metaphase

In metaphase, the chromosomes are aligned at the metaphase plate (a plane that is equally distant from the two spindle poles).

Anaphase

In anaphase, the paired chromosomes (sister chromatids) move to opposite ends of the cell.

Telophase

In this last stage, the chromosomes are cordoned off in distinct new nuclei in the emerging daughter cells. Cytokinesis is also occurring at this time.

At the end of mitosis, two distinct cells with identical genetic material are produced.

Before a dividing cell enters mitosis, it undergoes a period of growth called interphase. Some 90 percent of a cell's time in the normal cellular cycle may be spent in interphase.

View image of a cell in interphase.

Stages of Interphase

• G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.
• S phase: The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.
• G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.
• In the latter part of interphase, the cell still has nucleoli present.
• The nucleus is bounded by a nuclear envelope and the cell's chromosomes have duplicated but are in the form of chromatin.
• In animal cells, two pair of centrioles formed from the replication of one pair are located outside of the nucleus.

Muscle Tissue

Heart Muscle Cell

Muscle tissue is made of "excitable" cells that are capable of contraction. Of all of the different tissue types, muscle tissue is the most abundant in most animals.

Muscle Tissue Types

Muscle tissue contains numerous microfilaments composed of actin and myosin, which are contractile proteins.

There are three major types of muscle tissue:

• Cardiac Muscle
  
  Cardiac muscle is so named because it is found in the heart. Cells are joined to one another by intercalated discs which allow the synchronization of the heart beat. Cardiac muscle is branched, striated muscle.
  
  
• Skeletal Muscle
  
  Skeletal muscle, which is attached to bones by tendons, is associated with the body's voluntary movements. Skeletal muscle is striated muscle. Unlike cardiac muscle, the cells are not branched.
  
  
• Visceral (Smooth) Muscle
  
  Visceral muscle, is found in various parts of the body such as the arteries, the bladder, the digestive tract, as well as in many other organs.
  
  Visceral muscle is also called smooth muscle because it doesn't have cross striations. Visceral muscle contracts slower than skeletal muscle, but the contraction can be sustained over a longer period of time.

Interesting Tidbits About Muscle Tissue

Interestingly, adults have a certain number of muscle cells. Through exercise, such as weight lifting, the cells enlarge but the overall number of cells does not increase.

Skeletal muscles are voluntary muscles because we have control over their contraction. Visceral muscles are involuntary since, for the most part, they are not consciously controlled.

Epithelial Tissue

Epithelial Cell

What are Tissues?

The word tissue is derived from a Latin word meaning to "weave." Cells that make up tissues are sometimes "woven" together with extracellular fibers.

Likewise, a tissue can sometimes be held together by a sticky substance that coats its cells.

There are four main categories of tissues: epithelial, connective, muscle and nervous. Let's take a look at epithelial tissue.

Epithelial Tissue

Epithelial tissue covers the outside of the body and lines organs and cavities. The cells in this type of tissue are very closely packed together and joined with little space between them.

With a tightly packed structure we would expect epithelial tissue to perhaps serve some type of barrier and protective function and that is certainly the case.

Epithelial tissue helps to protect organisms from microorganisms, injury, and fluid loss.

In an epithelium, the free surface is usually exposed to fluid or the air while the bottom surface is attached to a basement membrane.

Classifying

Epithelia are commonly classified based on the shape of the cells on the free surface, as well as the number of cell layers. Sample types include:

Simple Epithelium: A simple epithelium has a single layer of cells.

Stratified Epithelium: A stratified epithelium has multiple layers of cells.

Likewise, the shape of the cells on the free surface can be:

Cuboidal
Analogous to the shape of dice.

Columnar
Analogous to the shape of bricks on an end.

Squamous 

 Analogous to the shape of flat tiles on a floor.

By combining the terms for shape and layers, we can derive epithelial types such as stratified squamous epithelium or simple columnar epithelium.

Nervous Tissue

Nerve Cell

Nervous tissue is responsible for sensing stimuli and transmitting signals to and from different parts of an animal.

Nervous Tissue: Neurons

Neurons are the basic unit of nervous tissue..

A neuron consists of two major parts:

• Cell Body
  
  The central cell body contains the neuron's nucleus, associated cytoplasm, and other organelles.
  
  
• Nerve Processes
  
  Nerve processes are "finger-like" projections from the cell body that are able to conduct and transmit signals. There are two types:
  
  Axons - typically carry signals away from the cell body.
  
  Dendrites - typically carry signals toward the cell body.
  

Neurons usually have one axon (can be branched however). Axons usually terminate at a synapse through which the signal is sent to the next cell, most often through a dendrite.

Unlike axons, dendrites are usually more numerous, shorter and more branched. As with other structures in organisms, there are exceptions.

Bundles of axons and dendrites are called nerves. They are sensory if they consist of dendrites only, motor if they consist of axons only and mixed if they consist of both.

Connective Tissue

Connective Tissue

Connective Tissue

As the name implies, connective tissue serves a "connecting" function. It supports and binds other tissues. Unlike epithelial tissue, connective tissue typically has cells scattered throughout an extracellular matrix.

Loose Connective Tissue

In vertebrates, the most common type of connective tissue is loose connective tissue. It holds organs in place and attaches epithelial tissue to other underlying tissues.

Loose connective tissue is named based on the "weave" and type of its constituent fibers. There are three main types:

• Collagenous Fibers
  
  Collagenous fibers are made of collagen and consist of bundles of fibrils that are coils of collagen molecules.
  
• Elastic Fibers
  
  Elastic fibers are made of elastin and are stretchable.
  
• Reticular Fibers
  
  Reticular fibers join connective tissues to other tissues.

Fibrous Connective Tissue

Another type of connective tissue is fibrous connective tissue which is found in tendons and ligaments. Fibrous connective tissue is composed of large amounts of closely packed collagenous fibers.

Specialized Connective Tissues

Adipose

Adipose tissue is a form of loose connective tissue that stores fat.

Cartilage

Cartilage is a form of fibrous connective tissue that is composed of closely packed collagenous fibers in a rubbery gelatinous substance called chondrin. The skeletons of sharks and human embryos are composed of cartilage. Cartilage also provides flexible support for certain structures in adult humans including the nose, trachea and ears.

Bone

Bone is a type of mineralized connective tissue that contains collagen and calcium phosphate, a mineral crystal. Calcium phosphate gives bone its firmness.

Blood

Interestingly enough, blood is considered to be a type of connective tissue. Even though it has a different function in comparison to other connective tissues it does have an extracellular matrix. The matrix is the plasma and erythrocytes, leukocytes and platelets are suspended in the plasma.

Difference between Gram -ve and Gram +ve Bacteria

Bacteria are generally classified into two groups on the basis of Gram staining based on the amount of peptidoglycan present in the cell wall.Though it is found that Gram positive and gram negative bacteria have certain other variable characteristics other than merely the result of Gram staining: Gram positive- 1.They retain the crystal violet stain after gram staining. 2.They have peptidoglycan layer thickness about 20-80nm and about 40-60 layers thick. 3.Peptidoglycan is much more mesh like and has interpeptide cross linkages. 4.cell wall has techoic acids which confer negative charges to the cell wall. 5.Have only one periplasmic space. Gram negative- 1.They retain the colour of safranine,the counter stain of gram stain, and not the colour of the primary stain crystal violet. 2.The cell wall has an additional layer outside the peptidoglycan layer known as the outer membrane. 3.The outer membrane contains lipid-A,core polysaccharide and the O-side chain. 4.Lipid A portion of core polysaccharide is known as endotoxin and help in virulence. 5.O side chain is also known as o specific antigen as it elicits an immune response. 6.Peptidoglycan has a thickness of 2-7 nm . 7.It has two periplasmic spaces on either side of petidoglycan layer.

Clssification of Bacteria

General Structure of Bacterium

The structural difference between the Prokaryotes and the Eukaryotes are so significant that some biologist think that these two groups merit the status of Super Kingdoms. The main distinguishing feature between the Prokaryotes and Eukaryotes is the lack of a true nucleus in the former.

The general size of a prokaryotic cell is about 1-2 um. Note the absence of membrane bound organelles There is no true nucleus with a nuclear membrane The ribosome's are smaller than eukaryotic cells The slime capsule is used as a means of attachment to a surface Only flagellate bacteria have the flagellum Plasmids are very small circular pieces of DNA that maybe transferred from one bacteria to another.

1.2.2 Function of Prokaryotic cell structures

Structure

Function

Cell Wall

Made of murein (not cellulose), which is a glycoprotein or peptidoglycan (i.e. a protein/carbohydrate complex). There are two kinds of bacterial cell wall, which are identified by the Gram Stain technique when observed under the microscope. Gram positive bacteria stain purple, while Gram negative bacteria stain pink. The technique is still used today to identify and classify bacteria. We now know that the different staining is due to two types of cell wall

Plasma membrane

Controls the entry and exit of substances, pumping some of them in by active transport .

Mesosome

A tightly-folded region of the cell membrane containing all the membrane-bound proteins required for respiration and photosynthesis. Can also be associated with the nucleoid. This is now thought to be an artifact of the electron microscope and not a real structure.

Cytoplasm

Contains all the enzymes needed for all metabolic reactions, since there are no organelles

Ribosome's

The smaller (70 S) type are all free in the cytoplasm, not attached to membranes (like RER). They are used in protein synthesis which is part of gene expression.

Naked DNA

Nucleoid is the region of the cytoplasm that contains DNA. It is not surrounded by a nuclear membrane. DNA is always circular (i.e. a closed loop), and not associated with any proteins to form chromatin. Sometimes confusingly referred to as the bacterial chromosome

Slime Capsule

A thick polysaccharide layer outside of the cell wall, like the glycocalyx of eukaryotes. Used for sticking cells together, as a food reserve, as protection against desiccation and chemicals, and as protection against phagocytosis. In some species the capsules of many cells in a colony fuse together forming a mass of sticky cells called a biofilm. Dental plaque is an example of a biofilm.

Bacteria of Medical Importance

Bacteria That Cause Human Disease

Only a small fraction of the thousands of species of bacteria on the earth cause disease in humans. Bacterial infection can be prevented by killing bacteria with heat, as in sterilization and pasteurization. If a bacterial infection does occur, doctors may treat it with antibiotics. However, overuse of antibiotics in recent years has enabled the development of strains of bacteria that are resistant to antibiotics, such as Mycobacterium tuberculosis, which causes tuberculosis.

Bacterium

Disease

Bacillus
Bacillus anthracis	Anthrax
Bacillus cereus	B. cereus food poisoning
Clostridium botulinum	Botulism
Clostridium perfringens	Clostridial myonecrosis (gas gangrene)
Clostridium tetani	Tetanus (lockjaw)
Corynebacterium diphtheriae	Diphtheria
Escherichia coli	Diarrhea
Klebsiella pneumoniae	Bronchopneumonia
Legionella pneumophila	Legionnaire's disease
Mycobacterium leprae	Leprosy
Mycobacterium tuberculosis	Tuberculosis
Salmonella species	Salmonella
Salmonella typhi	Typhoid fever
Salmonella typhimurium	Salmonella gastroenteritis
Shigella dysenteriae	Bacillary dysentery
Shigella species	Shigellosis
Yersinia enterocolitica	Yersiniosis, gastroenteritis
Yersinia pestis	Plague
Yersinia pseudotuberculosis	Mesenteric lymphadenitis
Chlamydia
Chlamydia trachomatis	Trachoma, urethritis, cervicitis, conjunctivitis
Coccobacillus
Bordetella pertussis	Pertussis (whooping cough)
Brucella species	Undulant fever
Hemophilus influenzae	Meningitis, bacterial pneumonia
Hemophilus pertussis	Pertussis (whooping cough)
Coccus
Neisseria gonorrhoeae	Gonorrhea, pelvic inflammatory disease
Neisseria meningitidis	Meningitis
Staphylococcus aureus	Pneumonia, toxic shock syndrome, skin infections, meningitis
Streptococcus pneumoniae	Pneumonia, ear infections, meningitis
Streptococcus pyogenes	Strep throat, rheumatic fever
Streptococcus species	Scarlet fever, puerperal fever
Listeria
Listeria monocytogenes	Listeriosis, perinatal septicemia, meningitis, encephalitis, intrauterine infections
Mycoplasma
Mycoplasma pneumoniae	Pneumonia
Rickettsia
Rickettsia prowazekii	Epidemic typhus, Brill-Zinsser disease (spread by lice)
Rickettsia rickettsii	Rocky Mountain spotted fever (spread by ticks)
Rickettsia typhi	Endemic typhus (murine typhus, spread by rat fleas)
Spirillus
Campylobacter fetus jejuni	Campylobacteriosis (bacterial diarrheal illness)
Spirillum minor	Rat-bite fever
Spirochete
Treponema pallidum	Syphilis
Vibrio
Aeromonas hydrophila	Gastroenteritis, septicemia, cellulitis, wound infections, urinary tract infections
Plesiomonas shigelloides	Gastroenteritis, diarrhea
Vibrio cholerae 01	Epidemic cholera
Vibrio cholerae non-01	Gastroenteritis
Vibrio parahemolyticus	V. parahemolyticus-associated gastroenteritis
Vibrio vulnificus	Wound infections, gastroenteritis, primary septicemia

Personal Development

Introduction to Development, Personality, and Stage Theories

When discussing any type of development, most theorist break it down into specific stages.  These stages are typically progressive.  In other words, you must pass through one stage before you can get to the next.  Think about how you learned to run; first you had to learn to crawl, then you could learn to walk, and finally you could develop the skills needed to run.  Without the first two stages, running would be an impossibility.

In this chapter we will discuss the most prominent stage theories in regard to motor and cognitive, social development, development, and moral development.  Most of these stage theories are progressive, although in some, such as Erikson's psychosocial and Freud's psychosexual, a person can fail to complete the stage while still continuing.  This failure, however, will result in difficulties later in life according to the theories.  The following offers an overview of development according to the principles of psychology.

Motor Development in Infancy and Childhood

Most infants develop motor abilities in the same order and at approximately the same age. In this sense, most agree that these abilities are genetically preprogrammed within all infants. The environment does play a role in the development, with an enriched environment often reducing the learning time and an impoverished one doing the opposite.

The following chart delineates the development of infants in sequential order. The ages shown are averages and it is normal for these to vary by a month or two in either direction.

2 months – able to lift head up on his own

3 months – can roll over

4 months – can sit propped up without falling over

6 months – is able to sit up without support

7 months – begins to stand while holding on to things for support

9 months – can begin to walk, still using support

10 months – is able to momentarily stand on her own without support

11 months – can stand alone with more confidence

12 months – begin walking alone without support

14 months – can walk backward without support

17 months – can walk up steps with little or no support

18 months – able to manipulate objects with feet while walking, such as kicking a ball

Cognitive Development in Children

Probably the most cited theory in the cognitive development in children is Jean Piaget (1896-1980). As with all stage theories, Piaget’s Theory of Cognitive Development maintains that children go through specific stages as their intellect and ability to see relationships matures. These stages are completed in a fixed order with all children, even those in other countries. The age range, however can vary from child to child.

Sensorimotor Stage. This stage occurs between the ages of birth and two years of age, as infants begin to understand the information entering their sense and their ability to interact with the world. During this stage, the child learns to manipulate objects although they fail to understand the permanency of these objects if they are not within their current sensory perception. In other words, once an object is removed from the child’s view, he or she is unable to understand that the object still exists.

The major achievement during this stage is that of Object Permanency, or the ability to understand that these objects do in fact continue to exist. This includes his ability to understand that when mom leaves the room, she will eventually return, resulting in an increased sense of safety and security. Object Permanency occurs during the end of this stage and represents the child’s ability to maintain a mental image of the object (or person) without the actual perception.

Preoperational Stage. The second stage begins after Object Permanency is achieved and occurs between the ages of two to seven years of age. During this stage, the development of language occurs at a rapid pace. Children learn how to interact with their environment in a more complex manner through the use of words and images. This stage is marked by Egocentrism, or the child’s belief that everyone sees the world the same way that she does. The fail to understand the differences in perception and believe that inanimate objects have the same perceptions they do, such as seeing things, feeling, hearing and their sense of touch.

A second important factor in this stage is that of Conservation, which is the ability to understand that quantity does not change if the shape changes. In other words, if a short and wide glass of water is poured into a tall and thin glass. Children in this stage will perceive the taller glass as having more water due only because of it’s height. This is due to the children’s inability to understand reversibility and to focus on only one aspect of a stimulus (called centration), such as height, as opposed to understanding other aspects, such as glass width.

Concrete Operations Stage. Occurring between ages 7 and about 12, the third stage of cognitive development is marked by a gradual decrease in centristic thought and the increased ability to focus on more than one aspect of a stimulus. They can understand the concept of grouping, knowing that a small dog and a large dog are still both dogs, or that pennies, quarters, and dollar bills are part of the bigger concept of money.

They can only apply this new understanding to concrete objects ( those they have actually experienced). In other words, imagined objects or those they have not seen, heard, or touched, continue to remain somewhat mystical to these children, and abstract thinking has yet to develop.

Formal Operations Stage. In the final stage of cognitive development (from age 12 and beyond), children begin to develop a more abstract view of the world. They are able to apply reversibility and conservation to both real and imagined situations. They also develop an increased understanding of the world and the idea of cause and effect. By the teenage years, they are able to develop their own theories about the world. This stage is achieved by most children, although failure to do so has been associated with lower intelligence.

Erikson’s Stages of Psychosocial Development

Like Piaget, Erik Erikson (1902-1994) maintained that children develop in a predetermined order. Instead of focusing on cognitive development, however, he was interested in how children socialize and how this affects their sense of self. Erikson’s Theory of Psychosocial Development has eight distinct stage, each with two possible outcomes. According to the theory, successful completion of each stage results in a healthy personality and successful interactions with others. Failure to successfully complete a stage can result in a reduced ability to complete further stages and therefore a more unhealthy personality and sense of self. These stages, however, can be resolved successfully at a later time.

Trust Versus Mistrust. From ages birth to one year, children begin to learn the ability to trust others based upon the consistency of their caregiver(s). If trust develops successfully, the child gains confidence and security in the world around him and is able to feel secure even when threatened. Unsuccessful completion of this stage can result in an inability to trust, and therefore an sense of fear about the inconsistent world. It may result in anxiety, heightened insecurities, and an over feeling of mistrust in the world around them.

Autonomy vs. Shame and Doubt. Between the ages of one and three, children begin to assert their independence, by walking away from their mother, picking which toy to play with, and making choices about what they like to wear, to eat, etc. If children in this stage are encouraged and supported in their increased independence, they become more confident and secure in their own ability to survive in the world. If children are criticized, overly controlled, or not given the opportunity to assert themselves, they begin to feel inadequate in their ability to survive, and may then become overly dependent upon others, lack self-esteem, and feel a sense of shame or doubt in their own abilities.

Initiative vs. Guilt. Around age three and continuing to age six, children assert themselves more frequently. They begin to plan activities, make up games, and initiate activities with others. If given this opportunity, children develop a sense of initiative, and feel secure in their ability to lead others and make decisions. Conversely, if this tendency is squelched, either through criticism or control, children develop a sense of guilt. They may feel like a nuisance to others and will therefore remain followers, lacking in self-initiative.

Industry vs. Inferiority. From age six years to puberty, children begin to develop a sense of pride in their accomplishments. They initiate projects, see them through to completion, and feel good about what they have achieved. During this time, teachers play an increased role in the child’s development. If children are encouraged and reinforced for their initiative, they begin to feel industrious and feel confident in their ability to achieve goals. If this initiative is not encouraged, if it is restricted by parents or teacher, then the child begins to feel inferior, doubting his own abilities and therefore may not reach his potential.

Identity vs. Role Confusion. During adolescence, the transition from childhood to adulthood is most important. Children are becoming more independent, and begin to look at the future in terms of career, relationships, families, housing, etc. During this period, they explore possibilities and begin to form their own identity based upon the outcome of their explorations. This sense of who they are can be hindered, which results in a sense of confusion ("I don’t know what I want to be when I grow up") about themselves and their role in the world.

Intimacy vs. Isolation. Occurring in Young adulthood, we begin to share ourselves more intimately with others. We explore relationships leading toward longer term commitments with someone other than a family member. Successful completion can lead to comfortable relationships and a sense of commitment, safety, and care within a relationship. Avoiding intimacy, fearing commitment and relationships can lead to isolation, loneliness, and sometimes depression.

Generativity vs. Stagnation. During middle adulthood, we establish our careers, settle down within a relationship, begin our own families and develop a sense of being a part of the bigger picture. We give back to society through raising our children, being productive at work, and becoming involved in community activities and organizations. By failing to achieve these objectives, we become stagnant and feel unproductive.

Ego Integrity vs. Despair. As we grow older and become senior citizens, we tend to slow down our productivity, and explore life as a retired person. It is during this time that we contemplate our accomplishments and are able to develop integrity if we see ourselves as leading a successful life. If we see our lives as unproductive, feel guilt about our pasts, or feel that we did not accomplish our life goals, we become dissatisfied with life and develop despair, often leading to depression and hopelessness.

Freud’s Stages of Psychosexual Development

Sigmund Freud (1856-1939) is probably the most well known theorist when it comes to the development of personality. Freud’s Stages of Psychosexual Development are, like other stage theories, completed in a predetermined sequence and can result in either successful completion or a healthy personality or can result in failure, leading to an unhealthy personality. This theory is probably the most well known as well as the most controversial, as Freud believed that we develop through stages based upon a particular erogenous zone. During each stage, an unsuccessful completion means that a child becomes fixated on that particular erogenous zone and either over– or under-indulges once he or she becomes an adult.

Oral Stage (Birth to 18 months). During the oral stage, the child if focused on oral pleasures (sucking). Too much or too little gratification can result in an Oral Fixation or Oral Personality which is evidenced by a preoccupation with oral activities. This type of personality may have a stronger tendency to smoke, drink alcohol, over eat, or bite his or her nails. Personality wise, these individuals may become overly dependent upon others, gullible, and perpetual followers. On the other hand, they may also fight these urges and develop pessimism and aggression toward others.

Anal Stage (18 months to three years). The child’s focus of pleasure in this stage is on eliminating and retaining feces. Through society’s pressure, mainly via parents, the child has to learn to control anal stimulation. In terms of personality, after effects of an anal fixation during this stage can result in an obsession with cleanliness, perfection, and control (anal retentive). On the opposite end of the spectrum, they may become messy and disorganized (anal expulsive).

Phallic Stage (ages three to six). The pleasure zone switches to the genitals. Freud believed that during this stage boy develop unconscious sexual desires for their mother. Because of this, he becomes rivals with his father and sees him as competition for the mother’s affection. During this time, boys also develop a fear that their father will punish them for these feelings, such as by castrating them. This group of feelings is known as Oedipus Complex ( after the Greek Mythology figure who accidentally killed his father and married his mother).

Later it was added that girls go through a similar situation, developing unconscious sexual attraction to their father. Although Freud Strongly disagreed with this, it has been termed the Electra Complex by more recent psychoanalysts.

According to Freud, out of fear of castration and due to the strong competition of his father, boys eventually decide to identify with him rather than fight him. By identifying with his father, the boy develops masculine characteristics and identifies himself as a male, and represses his sexual feelings toward his mother. A fixation at this stage could result in sexual deviancies (both overindulging and avoidance) and weak or confused sexual identity according to psychoanalysts.

Latency Stage (age six to puberty). It’s during this stage that sexual urges remain repressed and children interact and play mostly with same sex peers.

Genital Stage (puberty on). The final stage of psychosexual development begins at the start of puberty when sexual urges are once again awakened. Through the lessons learned during the previous stages, adolescents direct their sexual urges onto opposite sex peers, with the primary focus of pleasure is the genitals.

Freud's Structural and Topographical Models of 

Personality

 

Sigmund Freud's Theory is quite complex and although his writings on psychosexual development set the groundwork for how our personalities developed, it was only one of five parts to his overall theory of personality.  He also believed that different driving forces develop during these stages which play an important role in how we interact with the world.

Structural Model (id, ego, superego)

According to Freud, we are born with our Id.  The id is an important part of our personality because as newborns, it allows us to get our basic needs met.  Freud believed that the id is based on our pleasure principle.  In other words, the id wants whatever feels good at the time, with no consideration for the reality of the situation.  When a child is hungry, the id wants food, and therefore the child cries.  When the child needs to be changed, the id cries.  When the child is uncomfortable, in pain, too hot, too cold, or just wants attention, the id speaks up until his or her needs are met.

The id doesn't care about reality, about the needs of anyone else, only its own satisfaction.  If you think about it, babies are not real considerate of their parents' wishes.  They have no care for time, whether their parents are sleeping, relaxing, eating dinner, or bathing.  When the id wants something, nothing else is important.

Within the next three years, as the child interacts more and more with the world, the second part of the personality begins to develop.  Freud called this part the Ego.  The ego is based on the reality principle.  The ego understands that other people have needs and desires and that sometimes being impulsive or selfish can hurt us in the long run.  Its the ego's job to meet the needs of the id, while taking into consideration the reality of the situation.  

By the age of five, or the end of the phallic stage of development, the Superego develops.  The Superego is the moral part of us and develops due to the moral and ethical restraints placed on us by our caregivers.  Many equate the superego with the conscience as it dictates our belief of right and wrong.

In a healthy person, according to Freud, the ego is the strongest so that it can satisfy the needs of the id, not upset the superego, and still take into consideration the reality of every situation.  Not an easy job by any means, but if the id gets too strong, impulses and self gratification take over the person's life.  If the superego becomes to strong, the person would be driven by rigid morals, would be judgmental and unbending in his or her interactions with the world.  You'll learn how the ego maintains control as you continue to read.

Topographical Model

Freud believed that the majority of what we experience in our lives, the underlying emotions, beliefs, feelings, and impulses are not available to us at a conscious level.  He believed that most of what drives us is buried in our unconscious.  If you remember the Oedipus and Electra Complex, they were both pushed down into the unconscious, out of our awareness due to the extreme anxiety they caused.  While buried there, however, they continue to impact us dramatically according to Freud.

The role of the unconscious is only one part of the model.  Freud also believed that everything we are aware of is stored in our conscious.  Our conscious makes up a very small part of who we are.  In other words, at any given time, we are only aware of a very small part of what makes up our personality; most of what we are is buried and inaccessible.

The final part is the preconscious or subconscious.  This is the part of us that we can access if prompted, but is not in our active conscious.  Its right below the surface, but still buried somewhat unless we search for it.  Information such as our telephone number, some childhood memories, or the name of your best childhood friend is stored in the preconscious.

Because the unconscious is so large, and because we are only aware of the very small conscious at any given time, this theory has been likened to an iceberg, where the vast majority is buried beneath the water's surface.  The water, by the way, would represent everything that we are not aware of, have not experienced, and that has not been integrated into our personalities, referred to as the nonconscious

Freud's Ego Defense Mechanisms

We stated earlier that the ego's job was to satisfy the id's impulses, not offend the moralistic character of the superego, while still taking into consideration the reality of the situation.  We also stated that this was not an easy job.  Think of the id as the 'devil on your shoulder' and the superego as the 'angel of your shoulder.'  We don't want either one to get too strong so we talk to both of them, hear their perspective and then make a decision.  This decision is the ego talking, the one looking for that healthy balance.

Before we can talk more about this, we need to understand what drives the id, ego, and superego.  According to Freud, we only have two drives; sex and aggression.  In other words, everything we do is motivated by one of these two drives.

Sex, also called Eros or the Life force, represents our drive to live, prosper, and produce offspring.  Aggression, also called Thanatos or our Death force, represents our need to stay alive and stave off threats to our existence, our power, and our prosperity.

Now the ego has a difficult time satisfying both the id and the superego, but it doesn't have to do so without help.  The ego has some tools it can use in its job as the mediator, tools that help defend the ego.  These are called Ego Defense Mechanisms or Defenses.  When the ego has a difficult time making both the id and the superego happy, it will employ one or more of these defenses:

 

DEFENSE	DESCRIPTION	EXAMPLE
denial	arguing against an anxiety provoking stimuli by stating it doesn't exist	denying that your physician's diagnosis of cancer is correct and seeking a second opinion
displacement	taking out impulses on a less threatening target	slamming a door instead of hitting as person, yelling at your spouse after an argument with your boss
intellectualization	avoiding unacceptable emotions by focusing on the intellectual aspects	focusing on the details of a funeral as opposed to the sadness and grief
projection	placing unacceptable impulses in yourself onto someone else	when losing an argument, you state "You're just Stupid;" homophobia
rationalization	supplying a logical or rational reason as opposed to the real reason	stating that you were fired because you didn't kiss up the the boss, when the real reason was your poor performance
reaction formation	taking the opposite belief because the true belief causes anxiety	having a bias against a particular race or culture and then embracing that race or culture to the extreme
regression	returning to a previous stage of development	sitting in a corner and crying after hearing bad news; throwing a temper tantrum when you don't get your way
repression	pulling into the unconscious	forgetting sexual abuse from your childhood due to the trauma and anxiety
sublimation	acting out unacceptable impulses in a socially acceptable way	sublimating your aggressive impulses toward a career as a boxer; becoming a surgeon because of your desire to cut; lifting weights to release 'pent up' energy
suppression	pushing into the unconscious	trying to forget something that causes you anxiety

Ego defenses are not necessarily unhealthy as you can see by the examples above.  In face, the lack of these defenses, or the inability to use them effectively can often lead to problems in life.  However, we sometimes employ the defenses at the wrong time or overuse them, which can be equally destructive.

Kohlberg’s Stages of Moral Development

Although it has been questioned as to whether it applied equally to different genders and different cultures, Kohlberg’s (1973) stages of moral development is the most widely cited. It breaks our development of morality into three levels, each of which is divided further into two stages:

Preconventional Level (up to age nine):

     ~Self Focused Morality~

1. Morality is defined as obeying rules and avoiding negative consequences. Children in this stage see rules set, typically by parents, as defining moral law.

2. That which satisfies the child’s needs is seen as good and moral.

Conventional Level (age nine to adolescence):

     ~Other Focused Morality~

3. Children begin to understand what is expected of them by their parents, teacher, etc. Morality is seen as achieving these expectations.

4. Fulfilling obligations as well as following expectations are seen as moral law for children in this stage.

Postconventional Level (adulthood):

     ~Higher Focused Morality~ 

5. As adults, we begin to understand that people have different opinions about morality and that rules and laws vary from group to group and culture to culture. Morality is seen as upholding the values of your group or culture.

6. Understanding your own personal beliefs allow adults to judge themselves and others based upon higher levels of morality. In this stage what is right and wrong is based upon the circumstances surrounding an action. Basics of morality are the foundation with independent thought playing an important role.