The skin is one of the largest organs of the body and has many different functions. The skin functions in thermoregulation, protection, metabolic functions and sensation. The skin is divided into two main regions, the epidermis, and the dermis, each providing a distinct role in the overall function of the skin. The dermis is attached to an underlying hypodermis, also called subcutaneous connective tissue, which stores adipose tissue and is recognized as the superficial fascia of gross anatomy.

The skin forms the outer covering of the body. It is a strong elastic covering that encloses the body and protects it from damage by injury or infection. An average man is covered by approxiamtely 18 square feet of skin which weighs about 4.1kg.

The skin varies in thickness from 0.05mm to 5mm. As in other mammals, human skin is composed of an outer layer, the epidermis, and an underlying layer of fibrous tissue called the dermis. Beneath the dermis is the subcutaneous fat. The thickest skin is found on the sole of the foot and palm of the hand, some of the thinnest skin is found on the eyelid.

The epidermis is constantly growing from the bottom upwards and the dead skin cells (stratum corneum) are shed (usually invisibly) from the surface. This whole process normally takes about 52-75 days but can be much quicker in some skin diseases such as psoriasis.

In the deeper parts of the dermis are hair follicles, from which hair grows. It varies in thickness from about 0.005mm in the fine ‘lanugo’ hair covering a fetus to 0.2mm in beard hair. It varies in length from 1mm or less to 1.5m in extreme instances.

Oil glands (sebaceous glands) are found attached to hair follicles, Sweat glands are found in the dermis with ducts passing to the surface through the epidermis. In certain areas such as the axilla and groin there are specialised sweat glands called apocrine glands which develop after puberty. In addition there are specialised sense organs and nerves, blood vessels and other tissues such as muscle, which make the skin one of the most complex organs in the body.

Sweat glands occur in varying numbers over most of the body. For example, there are approximately 3000 square inches in the palm of the hand and sole of the foot, compared with 500 square inches in the badck. Specialised sweat glands are found in the armpit and genital area.

Sensations of pain, touch and temperature are conveyed to the brain from nerve endings in the skin. Some sensory nerve endings are highly specialised in shape and form, and their distribution varies gratly in the body. Finger tips and lips have a great many nerve endings. In other areas, like the forearm and abdomen, nerve endings are more sparse.

There are two main kinds of human skin; Glaborous skin (non-hairy skin) and hair-bearing skin. Glaborous skin is found on the palms and soles and is characterised by a thick epidermis with dermatoglyphics (fingerprints). Hairy skin differs from site to site, for example, the scalp versus the arm. It also contains a wide range of other structures depending on the part of the skin examined. Hair grows in different densities, patterns and colour over the skin. It is not found on the palm or the sole. Alongside some of the roots of the hair are sebaceous glands which produce a hair-bearing areas, and on the face, especially beside the nose.

Nails are a highly specialised and much changed form of the epidermis. They are semi-transparent and the underlying tissue, rich in blood vessels, shines through.

Personality psychology is a branch of psychology which studies personality and individual different processes – that which makes us into a person. One emphasis is on trying to create a coherent picture of a person and all his or her major psychological processes. Another emphasis views it as the study of individual differences. These two views work together in practice. Personality psychologists are interested in a broad view of the individual. This often leads to an interest in the most salient individual differences among people.

In psychology, personality is a collection of emotional, thought and behavioral patterns unique to a person that is consistent over time. The word originates from the Latin persona, which means “mask.” Significantly, in the theatre of the ancient Latin-speaking world, the mask was not used as a plot device to disguise the identity of a character, but rather was a convention employed to represent, or typify that character.

There are several theoretical perspectives on personality in psychology, which involve different ideas about the relationship between personality and other psychological constructs, as well as different theories about the way personality develops. Most theories can be grouped into one of the following classes.

Generally the opponents to personality theories claim that personality is “plastic” in time, places, moods and situations. Changing personality may in fact resulting from diet (or lack of), medical effects, historical or subsequent events, or learning. Stage managers (of many types) are especially skilled in changing a person’s resulting “personality”. Most personality theories will not cover such flexible nor unusual people situations.

Types of personality tests include the Holland Codes, the Rorschach test, the Minnesota Multiphasic Personality Inventory, the Myers-Briggs Type Indicator, NEO PI-R, and the Thematic Apperception Test. Critics have pointed to the Forer effect to suggest that some of these appear to be more accurate and discriminating than they really are.

Personality psychology is often closely associated with social psychology.

Around the 1990s, neuroscience entered the domain of personality psychology. Whereas previous efforts for identifying personality differences relied upon simple, direct, human observation, neuroscience introduced powerful brain analysis tools like Electroencephalography(EEG), Positron Emission Tomography(PET), and Functional Magnetic Resonance Imaging(fMRI) to this study. One of the founders of this area of brain research is Richard Davidson of the University of Wisconsin-Madison. Mr Davidson’s research lab has focused on the role of the prefrontal cortec(PFC) and amygdala in manifesting human personality. In particular, this research has looked at hemispheric asymmetry of activity in these regions.

Observational learning or social learning is learning that occurs as a function of observing, retaining and replicating behaviour observed in others. It is most associated with the work of psychologist Albert Bandura, who implemented some of the seminal studies in the area and initiated social learning theory.

Although observational learning can take place at any stage in life, it is thought to be particularly important during childhood, particularly as authority becomes important.

Because of this, social learning theory has influenced debates on the effect of television violence and parental role models. Bandura’s Bobo doll experiment is widely cited in psychology as a demonstration of observational learning and demonstrated that children are more likely to engage in violent play with a life size rebounding doll after watching an adult do the same.

Observational learning allows for learning without any change in behaviour and has therefore been used as an argument against strict behaviourism which argued that behaviour change must occur for new behaviours to be acquired.

Social Learning Theory
The social learning theory of Bandura emphasizes the importance of observing and modeling the behaviors, attitudes, and emotional reactions of others.

Bandura (1977) states: “Learning would be exceedingly laborious, not to mention hazardous, if people had to rely solely on the effects of their own actions to inform them what to do. Fortunately, most human behavior is learned observationally through modeling: from observing others one forms an idea of how new behaviors are performed, and on later occasions this coded information serves as a guide for action.” (p22).

Social learning theory explains human behavior in terms of continuous reciprocal interaction between cognitive, behavioral, an environmental influences. The component processes underlying observational learning are:
(1) Attention, including modeled events (distinctiveness, affective valence, complexity, prevalence, functional value) and observer characteristics (sensory capacities, arousal level, perceptual set, past reinforcement),
(2) Retention, including symbolic coding, cognitive organization, symbolic rehearsal, motor rehearsal),
(3) Motor Reproduction, including physical capabilities, self-observation of reproduction, accuracy of feedback, and
(4) Motivation, including external, vicarious and self reinforcement.

Social learning theory explains behaviour patterns as having been learned through a process of operant conditioning and observational learning. According to social learning theorists, the reinforcement, punishment, and models are provided by the social environment.



Scope/Application
Social learning theory has been applied extensively to the understanding of aggression (Bandura, 1973) and psychological disorders, particularly in the context of behavior modification (Bandura, 1969). It is also the theoretical foundation for the technique of behavior modeling which is widely used in training programs. In recent years, Bandura has focused his work on the concept of self-efficacy in a variety of contexts (e.g., Bandura, 1997).

The most common (and pervasive) examples of social learning situations are television commercials. Commercials suggest that drinking a certain beverage or using a particular hair shampoo will make us popular and win the admiration of attractive people. Depending upon the component processes involved (such as attention or motivation), we may model the behavior shown in the commercial and buy the product being advertised.

Principles
1. The highest level of observational learning is achieved by first organizing and rehearsing the modeled behavior symbolically and then enacting it overtly. Coding modeled behavior into words, labels or images results in better retention than simply observing.

2. Individuals are more likely to adopt a modeled behavior if it results in outcomes they value.
3. Individuals are more likely to adopt a modeled behavior if the model is similar to the observer and has admired status and the behavior has functional value.

Glucose, a simple form of sugar, enters the blood from the intestines, where it is absorbed from food and sugary drink as a natural part of digestion. It is also produced by the liver, which acts as a store of energy.

One of the many functions of the blood is to carry glucose around the body. When it reaches the various body tissues, such as the muscle cells, it is converted into energy. The precise concentration of glucose in the blood is automatically regulated. Crucial to this is the hormone insulin, which is secreted into the blood by the pancreas – a gland found behind the stomach.

Insulin is required for the conversion of glucose into energy. With the digestive system and liver working normally, a shortage of insulin causes glucose to build up in the blood, leading to the symptoms of diabetes.

Blood glucose is the amount of glucose in your blood at a given time. It is important to check your blood glucose because it will:

* Give you a quick measurement of your blood glucose level at that time
* Alert you if your blood glucose level is too high or too low
* Show you how food, exercise, medication, illness and even stress affect your blood glucose levels
* Help you and your diabetes healthcare team make changes to your lifestyle and medication that will improve your blood glucose management and long-term health.

There are two main types of diabetes – Type 1 and Type 2.

Type 1 diabetes is also known as insulin- dependent diabetes mellitus (IDDM). It can develop at any age, although it usually develops in children and young adults and is also referred to as juvenile onset diabetes. The affected person does not produce any of their own insulin and needs to take it by injection every day. Once it has developed, it is a life-long disease.

Type 2 diabetes occurs later in life and is sometimes known as late-onset diabetes or non-insulin-dependent diabetes (NIDDM). It is described more fully in the separate BUPA factsheet.

There are about 1.4 million people in the UK who are known to have diabetes – and possibly nearly as many again who have not yet been diagnosed. Around 15% of these have type 1 diabetes, making it much less common than type 2.

The “typical” menstrual cycle occurs regularly over 28 days. Most women have cycles with an interval that lasts from 21 to 35 days. Frequently cycles are unusually short or long during adolescence.

THE FIRST HALF OF THE MENSTRUAL CYCLE (Day 1 to About Day 14 in a 28-Day Cycle)

The Menstrual Phase
The first day of your menstrual period is considered Day 1 of your cycle. The menstrual phase includes your period. During this time, the endometrium (the built-up lining of the uterus) is shed, along with a little blood. Many of the problems that women experience with their menstrual cycle occur during this phase. For example, some women experience menstrual disorders such as dysmenorrhea(painful periods) or menorrhagia (unusually heavy periods).

The Follicular/Proliferate Phase
During the proliferate phase, the body produces a hormone called follicle-stimulating hormone (FSH). Follicle-stimulating hormone promotes the growth of a follicle (egg sac) within the ovary. An ovum (egg) matures in the follicle during the proliferative phase. FSH also stimulates the ovary to produce increasing amounts of estrogen. In turn, the estrogen causes endometrial tissue to build up (or proliferate), lining the interior of the uterus.

THE MIDPOINT OF THE MENSTRUAL CYCLE (About Day 14 in a 28-Day Cycle)

The mature ovum bursts from the follicle about midway (approximately 2 weeks before onset of next menstrual period) through the menstrual cycle. This process is known as ovulation. The ovum then travels from the ovary down the fallopian tube, and into the uterus.

The Luteal/Secretory Phase
Once the ovum has been released, the follicle becomes a sac known as the corpus luteum (“yellow body,” because it contains yellowish, fatty matter). A hormone called luteinizing hormone (LH) causes the corpus luteum to grow and to secrete progesterone, another female hormone.

During the secretory phase, progesterone makes the endometrial lining stronger and spongy in texture. Progesterone also stimulates glands in the endometrium. These glands produce uterine fluid, and their purpose is to support embryonic development if fertilization has occurred at or around the time of ovulation. It is in this phase of the menstrual cycle that women who suffer from premenstrual syndrome (PMS) may begin to experience their symptoms. Generally symptoms are worse during the last seven to ten days of the cycle, ending at or soon after the start of the menstrual period. In a woman who hasn’t become pregnant, the level of progesterone peaks about a week after ovulation and then begins to drop along with the estrogen level. The flow of blood to the endometrium decreases, and its upper portion is broken down and shed during menstruation. At the same time, the corpus luteum withers.

The dip in estrogen and progesterone at the end of the cycle help let the body know that it’s time to start the cycle all over again. The menstrual cycle doesn’t have to be a drag, it actually shows how complex your body is and a sign that it is functioning properly! Congratulations, you are a woman and being a woman is terrific!

Picture showing the ovarian cycle

Picture showing the Uterine Cycle

When girls begin to go through puberty (usually starting between the ages of 8 and 13), their bodies and minds change in many ways. The hormones in their bodies stimulate new physical development, such as growth and breast development. About 2 to 2 1/2 years after a girl’s breasts begin to develop, she usually gets her first menstrual period.

About 6 months or so before getting her first period, a girl might notice an increased amount of clear vaginal discharge This discharge is common. There’s no need for a girl to worry about discharge unless it has a strong odor or causes itchiness.

The start of periods is known as menarche (pronounced: meh-nar-kee). Menarche doesn’t happen until all the parts of a girl’s reproductive system have matured and are working together.

Baby girls are born with ovaries, fallopian tubes, and a uterus. As a girl matures and enters puberty, the pituiary gland releases hormones that stimulate the ovaries to produce other hormones called estrogen and progesterone. These hormones have many effects on a girl’s body, including physical maturation, growth, and emotions.

About once a month, a tiny egg leaves one of the ovaries – a process called ovulation – and travels down one of the fallopian tubes toward the uterus. In the days before ovulation, the hormone estrogen stimulates the uterus to build up its lining with extra blood and tissue, making the walls of the uterus thick and cushioned. This happens to prepare the uterus for pregnancy: If the egg reaches the uterus and is fertilized by a sperm cell, it attaches to the cushiony wall of the uterus, where it slowly develops into a baby.

If the egg isn’t fertilized, though – which is the case during most of a girl’s monthly cycles – it doesn’t attach to the wall of the uterus. When this happens, the uterus sheds the extra tissue lining. The blood, tissue, and unfertilized egg leave the uterus, going through the vagina on the way out of the body. This is a menstrual period. This cycle happens almost every month for several more decades (except, of course, when a female is pregnant) until a woman reaches menopause and no longer releases eggs from her ovaries.

Picture showing the interactions of hormones and the ovarian cycle

How Often Does a Girl Get Her Period?
Just as some girls begin puberty earlier or later than others, the same applies to periods. Some girls may start menstruating as early as age 9 or 10, but others may not get their first period until later in their teens. The amount of time between a girl’s periods is called her menstrual cycle (the cycle is counted from the start of one period to the start of the next). Some girls will find that their menstrual cycle lasts 28 days, whereas others might have a 24-day cycle, a 30-day cycle, or even a 35-day cycle.

Irregular periods are common in girls who are just beginning to menstruate. It may take the body a while to sort out all the changes going on. Usually, after a number of months, the menstrual cycle will become more regular. Many women continue to have irregular periods into adulthood, though.

As a girl gets older and her periods settle down – or she gets more used to her own unique cycle – she will probably find that she can predict when her period will come.

How Long and How Much?
The amount of time that a girl has her period also can vary. Some girls have periods that last just 2 or 3 days; other girls may have periods that last 7 days or longer. The menstrual flow – meaning how much blood comes out of the vagina – can vary widely from person to person, too. Some girls have such light blood flow that they wonder if they even have their period at all.

Other girls may be concerned that they’re losing too much blood. It can be a shock to see all that blood, but it’s highly unlikely that a girl will lose too much: For most girls an entire period consists of anywhere from a few spoonfuls to less than 1/2 cup (118 milliliters) of blood – it just looks like a lot!

Cramps, PMS, and Pimples

Some girls may notice physical or emotional changes around the time of their periods. Menstrual cramps are pretty common – in fact, more than half of all women who menstruate say they have cramps during the first few days of their periods. Doctors think that cramps are caused by prostaglandin, a chemical that causes the muscles of the uterus to contract.

Depending on the person, menstrual cramps can be dull and achy or sharp and intense, and they can sometimes be felt in the back or the thighs as well as the abdomen. These cramps often become less uncomfortable and sometimes even disappear completely as a girl gets older. In the meantime, many girls and women find that over-the-counter pain medications (like acetaminophen or ibuprofen) can relieve cramps, as can taking a warm bath or applying a warm heating pad to the lower abdomen. Exercising regularly throughout the monthly cycle may help lessen cramps, too. If these things don’t help, ask your doctor for advice.

Some girls and women find that they feel depressed or easily irritated during the few days or week before their periods. Others may get angry more quickly than normal or cry more than usual. Some girls crave certain foods. These types of emotional changes may be the result of premenstrual syndrome (PMS).