Introduction to human body

1. Introduction to the human body
The body is a very complex organism
It consists of many components
Starting with the smallest component and working towards the largest
Atoms & molecules-chemical level
Cells- the smallest structural units; organizations of various chemicals
Tissues-organizations of similar cells
Organs-organizations of different kinds of tissues
Systems- organizations of many different kinds of organs
Systems of the body
Circulatory
Respiratory
Skeletal
Muscular
Digestive
Excretory
Reproductive These organ systems are woven together because one can not work without other
Integumentary
Nervous
Endocrine
Immune
Lymphatic

2. Directional terms of the body
Body regions
Axial region - head, neck, and trunk which comprise the main vertical axis of our body
Appendicular region- limbs, or appendages, attach to the body’s axis
Quadrans of the body
Body cavities
Body cavities are spaces within the body.
Protect, separate , and support internal organs
Separate body cavities by Bones, muscles, ligaments, and other structures.

3. Cranial cavity contains brain
Spinal cavity contains spinal cord
Thoracic cavity contains heart, esophagus, trachea, thymus and several large blood vessels
Abdominal cavity, contains the stomach, spleen, liver, gallbladder, small intestine, and most of the large
intestine.
pelvic cavity, contains the urinary bladder, portions of the large intestine, and internal organs of the
reproductive system
Circulatory system
Contain the heart and all the blood vessels
Responsible for movement of blood, nutrients and gases
Heart pumps blood to lungs to receive oxygen and
to the rest of the body
Remove waste products
Major organs
Heart, Veins, Arteries, Capillaries, Blood
1.Heart
Size of your fist
Thick muscular walls
Divided in to two chambers
Upper chamber – atrium receives blood coming from the veins
Lower chamber- ventricles squeezes blood into the arteries
Blood
Pumps by the heart
Travel through thousands of miles of blood vessels
Carries nutrients, water, oxygen and waste products to and from the body cells
Contain blood cells and plasma

4. Plasma
Is straw colored liquid component of blood
It contain 90-92 of water and 8-9 of solid
Red blood cells
Carry oxygen from the lungs to all the cells of the body
Take carbon dioxide and transport it
back to the lungs
About 5,000,000 red blood cells in one blood drop
White blood cells
protect the body from germs
Attack and destroy germs when they enter the body
Contain neutrophils, lymphocytes, eosinophils, basophils
Platelets
Prevent and stop bleeding
Smallest component of blood and known as “thrombocytes”
Hemoglobin
Average Hb content is 14-16 gm/dl
Varies by gender and age
Need for carrying oxygen
ESR
ESR is the rate which the erythrocytes settle down
PCV
Amount of red cells in blood
Blood vessels
Hollow tubes that circulate the blood. There are three kind of blood vessels
Respiratory System
Situated in the thorax
Provide route for gain oxygen & excrete carbon dioxide (Gaseous exchange)
External respiration
Exchange of gases between the lungs and the blood
Internal respiration
Exchange of gases between the blood and the cells
Nasal cavity
Para nasal sinuses
Pharynx Upper respiratory tract
Larynx
Trachea
Bronchi Lower Respiratory tract
Bronchioles
Lungs (alveoli)
Pleura
Arteries
Veins
Capillaries

5. Nose
The air is Warming by high vascularity, Filter and Moistening (humidification)
Paranasal sinuses
A group of four paired air-filled cavities
Continue with the nasal cavity by tiny opening
Pharynx
A 12 -14 cm long muscular tube. Extends from the posterior nares (base of the skull) to the level of the C6
Three regions
The Nasopharynx -Lies behind the nose above the level of the soft palate
The Oropharynx- Oral part of the pharynx
The Laryngopharynx -Opening into the larynx and esophagus.
Functions
Passageway for air and food
Warming and humidifying air
Taste- oral and pharyngeal parts
Hearing -
Speech - acting as a resonating chamber
Larynx
Produce sound. By the intermittent release of expired air(exhalation) and
vibrating vocal cord
The epiglottis.
A leaf-shaped fibroelastic cartilage
Attached to the thyroid cartilage
That covers the glottis (superior opening of the larynx) during swallowing,
Preventing the entrance of food and drink into the larynx.
Trachea
Size – 10-12 cm long, 2cm diameter
Extend from end of Larynx (C6) to level of T5
Lies median plane in front of the oesophagus
It divides (bifurcates) into the right and left bronchi at the carina
Function
Passageway of air
Mucociliary escalator.
A defiance mechanism
Continues beating of cilia towards larynx
Maxillary sinuses
Frontal sinuses
Sphenoidal sinuses
Ethmoidal sinuses

6. Remove foreign particles from lungs (swallowed or expectorated)
Warming, humidifying and filtering of air
Cough reflex
Stimulate cough receptors in trachea & larynx
Nerve impulse travel to brain stem
Deep inspiration & close glottis
Contract diaphragm
Sudden forceful air release
Bronchi & bronchioles (Broncheal tree)
Trachea divides into two main (primary) bronchus
at T5 level
The alveoli are surrounded by a network of capillaries
The gases exchange takes place across alveolar and
capillary membranes
Lungs
Two lungs
Corn shaped
Composed with Bronchi and broncheoles, alveoli, connective tissue, blood vessels, lymph vessels and nerves
Right lung
Divided into three lobes
Superior, middle and inferior
Left lung
Divided into two lobes
Superior and inferior.
Pleural cavity
Space between visceral & parietal pleura
Contains a small amount of pleural fluid.
Preventing friction between two layers during breathing
Respiratory mechanism
Contract respiratory muscles
Increase capacity of thoracic cavity
Reduce pleural cavity pressure than atmospheric pressure
Visceral pleura follows the parietal pleura pulling the lung
Drawing air into the lungs
Air in the pleural cavity – Pneumothorax
Fluids in the pleural cavity – pleural effusion
Blood in the pleural cavity – Hemothrax
Pus in the pleural cavity – emphyema

7. Skeletal System
Includes bones, cartilage, ligament and bone marrows. About 206 bones in the adult human body
Bones are connected to each other by ligaments.
4 major functions
protection- protect vital organs
Organ are protected by skeleton
brain by skull
heart and lungs by ribs
2. Storage- store minerals and fat
3. Blood cell formation- make blood cells
4. Provide shape and support
Bones
Bones are made of calcium, mineral salt, cells and living parts
They are also made of stringe like material called ‘Collagen’
Bones have a red and yellow tube called ‘marrow’
The bone marrow produce red cells and store fat
The outer layer is called hard bone, the spongy bone is like a honeycomb
Bone is a strong and durable type of connective tissue
Joints
Where 2 or more bones come together
Some move- hip, Some don’t- skull
3 types of joints
Sliding joints- bones slide each other (hand)
Ball and socket joints- like a joystick in a computer game (Shoulder)
Hinge joint- like a door hinge, flex and extends (Knee)
Skull
Synonym- cranium
Protective cover of the brain
Provide structure for face and head
Consist 28 bones (Face and head)
Closely fitted together
Arms
Consist of three main bones and 15 small bones
Hand
27 bones and five fingers in each hand
The hand is very flexible with lots of joints
Spine
Contain 33 bones (Vertebra)
There are main 3 parts of the spine
Cervical, Thoracic, Lumbar
In the center of the spine is the spinal cord

8. Rib cage
The ribs, the spine and the sternum combine to make up the ribcage
Leg
The human leg contain 4 bones
Possible diseases
Osteoporosis
Rickets
Arthritis
Muscular system
Specialized tissue that enable the body and its parts to move
3 types
Smooth muscle- found only in digestive tract and blood vessels
Cardiac muscle- only found in hearts. Blood pump when contract
the muscle
Skeletal muscle- muscles attach to the bones
Functions
Movement
Maintenance of posture
Heat production
Protect the bones and internal organs
Use to give injections (Intra muscular injections)
Tendons- connect muscle to bones
Ligaments- connect bone to bone
Digestive system
The food passes through a continues canal which is divided in to various compartments
Major organs
Mouth
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
Salivary gland
Pancreas
Liver
Gall bladder
Functions
Ingestion of food
Digest food into smaller molecules and absorb nutrients
Remove undigested food from the body

9. Buckle cavity
The food chew and break down mechanically into small pieces
Esophagus
The swallowed food passes into the food pipe (Esophagus)
Food is pushed down by movement of wall of the esophagus
Stomach
Receive the food from esophagus
At the end of the esophagus it open into the stomach
Small intestine
It receive digestive secretions from the liver and pancreas
Liver- secreta bile and add to the small intestine
Bile stored at gallbladder
Large intestine
It absorb water and some salts from the undigested food materials
The remaining waste passes into the rectum and remaining there as semi
solid faeces
Anus
The faeced matter is removed through the anus from time to time
Excretory system
Remove waste products from the body
Major organs
Kidneys
Ureters
Bladder
Urethra
Lungs
Liver
Skin
Excretion by other organs
lungs- remove carbon dioxide and water vapor
Skin- excrete water, salts, and some wastes. Remove heat of the body
Liver- excrete many substances like bile pigments, heavy metals, drugs and toxins, bacteria etc…
The excretory function of these are limited.
Renal system has maximum capacity
Process of renal system
Kidneys produce the urine
Nephron is the functional unit of kidney and filter the urine and waste
Ureters transport the urine to the bladder
Urinary bladder stores the urine until it voided
Urine voided from bladder through urethra

10. Nervous system
Gather and interpret information
Responds to the information
Help maintain homeostasis
Coordinates activities of other organs and systems
Major organs
Brain
Spinal cord
Nerves
Diseases
Paralysis
Brain tumor
Psychiatric disorders
Alzheimer’s disease
Dementia
Endocrine system
Regulate body activities using hormones
Glands secrete hormones that regulate
processes such as growth, reproduction,
and nutrient use (metabolism) by body
cells.
Major organs
Hypothalamus
Pituitary gland
Thyroid gland
Thymus gland
Adrenal gland
Pancreas
Ovaries
Testes
Immune system
Fight for foreign invades for body.
Include white blood cells and macrophages
Defense mechanism help to prevent from infection
First line- skin, mucus membrane, hair, tears, saliva, ear Wax
Second line- phagocytoses fight with the germ
Cardinal signs- redness, heat, pain, swelling
Third line- when first line and second line unable to fight activate
The third line
Get the infection and produce antibodies

11. Integumentary system
Organs
Epidermis
Dermis
Sweat gland
Sebaceous gland
Hair follicle
Blood vessels
Nerves
Functions
Barrier against infection
Help to regulate body temperature
Remove excretory waste
Protect against sun UV rays
Production of vitamin D
Possible problems
Pressure ulcers
Lymphatic system
Picks up fluid leaked from blood vessels and returns it to blood. Disposes of debris in the lymphatic stream.
Houses white Blood cells (lymphocytes) involved in immunity. The immune response mounts the attack against
foreign substances within the body.
Include
Lymph
Lymph vessels
Lymph nodes
Spleen
Thymus
Reproductive system
Overall function is production of offspring.
Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female
reproductive tract.
Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization
and development of the fetus.
Mammary glands of female breasts produce milk to nourish the newborn.
Major organs
Ovaries
Uterus
Testes
Prostate gland
External genitalia
Mammary glands

12. Why diseases occurred
Disease is a disordered or incorrectly functioning organ, part, structure, or system of the body.
Causes of disease:
• Genetic or developmental errors
Aging
• Infection
• Poisons
• Nutritional deficiencies or imbalance
• Toxicity
• Unfavorable environmental factors
Signs of disease are objective; they can be measured.
Signs of Disease:
• Fever
• High blood pressure
• Rash
Symptoms of disease are subjective. Symptoms can’t be observed by another person; but a person that is
ill experiences them.
Symptoms of Disease:
• Dizziness
• Pain
• Blurry vision