Introduction HAP: Complete Notes and PDF

Introduction and Scope of Human Anatomy & Physiology

Human Body

INTRODUCTION:

Anatomy and physiology are concerned with the structures and functions of the human body.

Anatomy describes the structures of the body -- their scientific names, composition, location, and associated structures. Anatomy (a cutting open) is a plan or map of the body.
Physiology studies the function of each structure, individually and in combination with other structures.
Anatomy and physiology always work together. As we examine each part of the body, always consider both its structure and its function.

The study of anatomy is divided into 2 major fields:

1. Gross anatomy is the study of large visible structures.
2. Microscopic anatomy is the study of structures that are too small to see, such as cells and molecules.

1. Gross anatomy

also called macroscopic anatomy, is separated into 5 major divisions:

A. Surface anatomy describes surface forms and marks.

B. Regional anatomy describes the organization of specific areas of the body such as the head or hand. This approach is used mostly in professional schools: medical, dental, and physical therapy.

C. Systemic anatomy describes groups of organs that function together for a single purpose.

D. Developmental anatomy describes the structural changes in an organism from fertilized egg to maturity. Embryology is the anatomical study of early development.

E. Clinical anatomy describes various medical specialties, including medical anatomy (changes that occur during illness), and radiographic anatomy.

2. Microscopic anatomy is divided into two major divisions:

A. Cytology- is the study of cells and their structures.

B. Histology- is the study of tissues and their structures.

Physiology has many specialties. The 4 basic divisions are:

1. Cell physiology, including chemical and molecular processes within and between cells.
2. Special physiology, is the study of specific organs such as the heart.
3. Systemic physiology, the cooperative functions of all the organs in an organ system.

4. Pathological physiology, the effects of diseases on organs and organ systems.

Levels of Organization

Our bodies are organized at many different levels. The levels of organization of living things, from smallest to largest, are:

1. Atoms, are the smallest functional units of matter.
2. Molecules, active chemicals.
3. Organelles, are specialized structures within a cell.
4. Cells, are the smallest living units.
5. Tissues, are a group of similar cells that work together.
6. Organs, two or more tissue types working together.
7. Organ systems, are two or more organs working together.
8. Organism, a single individual, including all of the above

Level of Organization

Showing the different levels of Organization

The human body is divided into 11 interconnected organ systems. All organ systems work together, and many organs function in more than 1 organ system. These are as follows-

1. The Integumentary System: includes the skin & derived structures, it protects internal organs & helps maintain body temperature.
2. The Skeletal System: includes the bones & joints, it provides support & protection to internal organs.
3. The Muscular System: includes the skeletal muscle and it provides movement.
4. The Nervous System: includes the brain, spinal cord, and nerves. It provides regulation of body functions & sensory perception.
5. The Endocrine System: includes hormone-producing cells & glands. It regulates homeostasis, growth & development.
6. The Cardiovascular System: includes blood, heart, & blood vessels. It is responsible for the delivery of oxygen & nutrients to the tissues.
7. The Lymphatics & Immune System: includes lymphatic vessels & fluid. It is involved in the defense against infection.
8. The Respiratory System: includes the lungs & airways. It is involved in the absorption of oxygen & release of carbon dioxide.
9. The Digestive System: includes organs of the gastrointestinal tract. It is responsible for the absorption of nutrients.
10. The Urinary System: includes the kidneys, ureters, and bladder. It is responsible for electrolyte balance & waste removal.
11. The Reproductive System: includes the reproductive organs in males and females. It controls the biological process by which new individuals are produced.

HOMEOSTASIS:

• Ability to maintain relatively stable internal conditions despite a changing external environment. The dynamic state of equilibrium, or balance.
• The body is said to be in homeostasis when its cellular needs are adequately met and functional activities are occurring smoothly.
• Virtually every organ system plays a role in maintaining the internal environment. A homeostatic regulatory mechanism consists of 5 parts:

1. Receptors: It acts as sensors/receiver that responds to a stimulus. It monitors changes in control conditions.
2. Sensory Neurons: They send the input information/message to the control center, which means information from cells/tissue organs etc. to an integrated system i.e. brain and spinal cord.
3. Integrated System: analyzes the incoming message received from the sensory neurons and sends out commands/messages. In the body, there are hundred controlled conditions. A few examples are heart rate, blood pressure, temperature, and breathing rate.
4. Motor Neurons: The output information/message from the integrated center (brain and spinal cord) to cell/tissue/organ etc. are traveled by motor neurons.
5. Effectors: The cell/tissue/organ etc. act as an effector that responds according to the output command of the control/integrated center. Receptors, control center, and effectors maintain homeostasis by two mechanisms:

1. Negative feedback:

• When the response of effectors opposes the original stimulus, it is called negative feedback because it negates the stimulus.
• An example of negative feedback is the temperature thermostat in your home.
• Temperature sensors turn the air conditioner off and on to maintain air temperature within a specific, limited range.
• In the same way, the brain controls normal body-temperature homeostasis by negative feedback.
• Some stimulus (Stress) disrupts homeostasis (control condition) by an increase in body temperature.
• Due to this condition thermoreceptors (temperature-sensitive receptors) in the skin and brain activate and send input messages via nerve impulses to the control center.
• Control center analyzes the input message and sends the output message e to the effectors (skin).
• Effectors according to the output message of the control center increase sweating from sweat glands and causes increased heat loss by evaporation.
• Finally, decreases the temperature in the form of response and normalize the body temperature (control condition).

Feedback system

2. Positive feedback:

• The effector adds to the initial stimulus instead of negating it, speeding up the process.
• Labor contraction is an example of a positive feedback system.
• Labor contractions force the baby’s head or body into the birth canal.
• It produces an effect on the control condition and increases distention of the cervix of the uterus.
• It activates the stretch receptors of the cervix and sends an input message to the control center via sensory nerve impulse.
• Control center activates the hypothalamus and pituitary gland and sends the output message to increase oxytocin secretion in blood.
• Oxytocin produces its effect on the effector (cervix of the uterus) and causes distension of the cervix of the uterus than the normal value to push the baby further into the birth canal.
• Birth of the baby decreases distention of the cervix of the uterus and interrupts the positive feedback cycle.

BODY CAVITIES AND SEROUS MEMBRANES

• The body maintains its internal organization by means of membranes, sheaths, and other structures that separate compartments.
• The dorsal (posterior) cavity and the ventral (anterior) cavity are the largest body compartments.
• These cavities contain and protect delicate internal organs, and the ventral cavity allows for significant changes in the size and shape of the organs as they perform their functions.
• The lungs, heart, stomach, and intestines, for example, can expand and contract without distorting other tissues or disrupting the activity of nearby organs

Subdivisions of the Posterior (Dorsal) and Anterior (Ventral) Cavities

Body cavity

The posterior (dorsal) and anterior (ventral) cavities are each subdivided into smaller cavities. In the posterior (dorsal) cavity, the cranial cavity houses the brain, and the spinal cavity (or vertebral cavity) encloses the spinal cord

1. Superior thoracic cavity, containing:

A. Pleural cavity (left and right, divided by the mediastinum) organs: lungs membranes: visceral and parietal pleural

B. Pericardial cavity organs: heart membranes: visceral and parietal pericardium

2. Inferior abdominopelvic cavity, containing the

A. Peritoneal cavity membranes: visceral and parietal peritoneum

B. Abdominal cavity (superior peritoneal) organs: liver, stomach, spleen, intestine

C. Pelvic cavity (inferior peritoneal) organs: intestine, bladder, reproductive organs

Membranes of the Anterior (Ventral) Body Cavity:

• The walls of the ventral body cavity and the outer surfaces of the organs are covered with a thin, double-layered membrane – serosa or serous membranes.
• Part of the membrane lining the cavity walls - parietal serosa -folds on itself to form the visceral serosa which covers the organs in the cavity.
• Parietal - "parie"- means wall
• Visceral - "viscus"- means an organ in a body cavity

Chest (Ribs, Lungs, and Diaphragm,)

BODY FLUIDS:

The water content of the body is divided into:

1. Intracellular compartment (67%) - Inside the cell
2. Extracellular compartment (33%) - Outside the cell

Body fluids

 1.      Intracellular Fluid (ICF)

• Comprises, 2/3 of the body water.
• the If your body has 60% water, ICF is about 40% of your weight.
• The ICF is primarily a solution of potassium and organic anions, proteins, etc.
• The cell membranes and cellular metabolism control the constituents of this ICF.

2.  Extracellular compartment (ECF):

• It is the remaining 1/3 of your body's water.
• ECF is about 20% of the body weight.
• The ECF is primarily a NaCl and NaHCO3 solution.
• The ECF is further subdivided into three sub-compartments:
• Interstitial Fluid (ISF).
• Plasma.
• Transcellular fluid

Interstitial Fluid (ISF)

• Interstitial Fluid (ISF) surrounds the cells but does not circulate.
• It is the main component of the extracellular fluid
• It comprises about 3/4 of the ECF.
• Interstitial fluid is found in the interstitial spaces, also known as the tissue spaces.

Composition of Interstitial fluid

Functions of interstitial fluid

• Intercellular communication
• Interstitial fluids bathe the cells of tissues
• Removal of metabolic waste

B.     Plasma:

• It is the yellow liquid component of blood in which the blood cells in whole blood are normally suspended.
• 55% of the total blood volume.
• It is the intravascular fluid part of extracellular fluid (all body fluid outside of cells)
• It makes up about 1/4 of the ECF.

Composition of Plasma

Functions of Plasma

functions of Plasma

C.     Transcellular fluid

• Transcellular fluid is the portion of total body water contained within epithelial lined spaces.
• Smallest compartment.
• It is about 2.5% of the total body water.  Examples are-
• Cerebrospinal fluid
• Ocular fluid (Aqueous humor)
• Joint fluid (Synovial fluid)
• Urine

Composition of transcellular fluid-

                                I. Cerebrospinal fluid (CSF):

• The CSF is mainly produced by the choroid plexus
• The entire nervous system contains between 80-150 ml of CSF.
• It is a clear colorless liquid that contains White blood cells, glucose, protein, lactic acid, urea, cations (Na+, K+, Ca+, etc.), and, anions (Cl-, and HCO3-).

                             II. Ocular fluid (Aqueous humor):

• The aqueous humor is a transparent, gelatinous fluid similar to plasma.
• It is located in the anterior and posterior chambers of the eye, the space between the lens and the cornea.
• It contains Amino acids (transported by ciliary muscles), 98% water, Electrolytes, Ascorbic acid, Glutathione

                          III. Joint fluid (Synovial fluid):

• Synovial fluid is clear, pale yellow, viscid, and does not clot.
• The principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement.
• It contains Normal 3–4 mg/ml hyaluronic acid, a polymer of disaccharides, WBC, RBC, and proteins

                          IV. Urine:

• Urine is a typically sterile liquid by-product of the body secreted by the kidneys through a process called urination and excreted through the urethra.
• It contains 95% water, Organic solutes like urea, creatinine, uric acid, and trace amounts of enzymes, carbohydrates, hormones, fatty acids, pigments, and mucins, and inorganic ions such as sodium (Na+), potassium (K+), chloride (Cl-), magnesium (Mg2+), calcium (Ca2+), ammonium (NH4+), sulfates (SO42-), and phosphates (e.g., PO43-).

SOME DEFINITIONS RELATED TO HUMAN ANATOMY AND PHYSIOLOGY SUBJECT:

CELL: It is a \living structural and functional unit of the concerned body enclosed by a membrane.

CYTOLOGY: It is the branch of science with the study of cells.

TISSUE: It is a group of cells that usually have a common embryonic origin and function together for special activities.

BLOOD: It is a liquid connective tissue.

LYMPH: It is a thin, watery, clear, modified tissue fluid formed by the passage of substance from the blood capillaries into the tissue space (interstitial space) and enters into the closed system of lymphatic capillaries to lymphatic vessels and lymphatic sinus.

CARDIOVASCULAR SYSTEM: Cardiovascular is the system that includes the study of the heart, blood vessels, and blood.

IMMUNE SYSTEM: It is the collection of cells, tissues, and molecules that protects the body from numerous pathogenic microbes and toxins in our environment.

Terms used in Clinical Anatomy

1. The suffix, '-itis', means inflammation, e.g. appendicitis, tonsillitis, arthritis, neuritis, dermatitis, etc.
2. The suffix, '-ectomy', means removal from the body, e.g. appendicectomy, tonsillectomy, gastrectomy, nephrectomy, etc.
3. The suffix, '-otomy', means to open and then close a hollow organ, e.g. laparotomy, hysterotomy, cystotomy, cystolithotomy, etc.
4. The suffix, '-ostomy', means to open a hollow organ and leave it open, e.g. cystostomy, colostomy, tracheostomy, etc.
5. The suffix, '-oma’ means a tumor, e.g. lipoma, osteoma, neurofibroma, hemangioma, carcinoma, etc.
6. Puberty: The age at which the secondary sexual characters develop, being 12-15 years in girls and 13-16 years in boys.
7. Symptoms are subjective complaints of the patient about his disease.
8. Signs (physical signs) are objective findings of the doctor on the patient.
9. Diagnosis: Identification of a disease, or determination of the nature of a disease.
10. Prognosis: Forecasting the probable course and ultimate outcome of a disease.
11. Pyrexia: Fever.
12. Lesion: Injury, or a circumscribed pathologic change in the tissues.
13. Inflammation is the local reaction of the tissues to an injury or abnormal stimulation caused by a physical, chemical, or biological agent. It is characterized by: (a) Swelling; (b) pain; (c) redness; (d) warmth of heat; and (e) loss of function.
14. Oedema: Swelling due to accumulation of fluid in the extracellular space.
15. Thrombosis: Intravascular coagulation (solidification) of blood.
16. Embolism: Occlusion of a vessel by a detached and circulating thrombus (embolus).
17. Hemorrhage: Bleeding which may be external or internal.
18. Ulcer: A localized breach (gap, erosion) in the surface continuity of the skin or mucous membrane.
19. Sinus: A blind track (open at one end) lined by epithelium.
20. Fistula: A track open at both ends and lined by epithelium.
21. Necrosis: Local death of a tissue or organ due to irreversible damage to the nucleus.
22. Degeneration: A retrogressive change causing deterioration in the structural and functional qualities. It is a reversible process but may end in necrosis.
23. Gangrene: A form of necrosis (death) combined with putrefaction.
24. Infarction: Death (necrosis) of a tissue due to sudden obstruction of its artery of supply (often an end-artery).
25. Atrophy: Diminution in the size of cells, tissue, organ, or a part due to loss of its nutrition.
26. Dystrophy: Diminution in the size due to defective nutrition.
27. Hypertrophy: Increase size without any increase in the number of cells.
28. Hyperplasia: Increase in size due to an increase in the number of cells.
29. Hypoplasia: Incomplete development.
30. Aplasia: Failure of development.
31. Syndrome: A group of diverse symptoms and signs constituting together the picture of a disease.
32. Paralysis: Loss of motor power (movement) of a part of the body due to denervation or primary disease of the muscles.
33. Hemiplegia: Paralysis of one-half of the body.
34. Paraplegia: Paralysis of both lower limbs.
35. Monoplegia: Paralysis of any one limb.
36. Quadriplegia: Paralysis of all four limbs.
37. Anaesthesia: Loss of touch sensibility.
38. Analgesia: Loss of pain sensibility.
39. Thermanaesthesia: Loss of temperature sensibility.
40. Hyperaesthesia: Abnormally increased sensibility.
41. Paraesthesia: Perverted feeling of sensations.
42. Coma: Deep unconsciousness.
43. Tumour (neoplasm): A circumscribed, noninflammatory, abnormal growth arising from the body tissues.
44. Benign: Mild illness or growth which does not endanger life.
45. Malignant: Severe form of illness or growth, which is resistant to treatment and ends in death.
46. Carcinoma: Malignant growth arising from the epithelium (ectoderm or endoderm).
47. Sarcoma: Malignant growth arising from connective tissue (mesoderm).
48. Cancer: A general term used to indicate any malignant neoplasm which shows invasiveness and results in the death of the patient.
49. Metastasis: Spread of local disease (like cancer cells) to distant parts of the body.
50. Convalescence: The recovery period between the end of a disease and restoration to complete health.
51. Therapy: Medical treatment.