The Human Body 101
Anatomy and physiology
Levels of Organization in the Human Body
5. Organ
Systems
6.Organism
1.Chemicals
4. Organs
2. Cells
3. Tissues
Chemicals in the Human Body
• Water
• Makes up 60 – 70 % of human body
• Protein
• Protein is the main component of muscles, bones, connective tissue, organs, skin, nails,
hormones, enzymes
• Lipids (fats)
• Stored under skin and around organs
• Carbohydrates
• Glucose and glycogen
• DNA
• Makes up your genes
• Gases
Cells. What are they?
• A cell is the simplest unit of life.
• It is the smallest part of an organism that can exist on its
own.
• All organisms are made up of cells
How many cells are in the human body?
• As much as 40 trillion (40,000,000,000,000) cells
5
Types of Cells in the Human Body
• Epithelial cell
• Nerve cell
• Muscle cell
• Connective tissue cell
Epithelial Cells
• They cover over the interior of hollow organs, like blood
vessels or digestive organs, or else form the surface of
things, like the skin
• They protect the more delicate tissue beneath
Nerve Cells
• Also called NEURONES.
• Carry electrical impulses through the nervous system
and allows us to sense and respond to our
environment
Muscle Cells
• Contract and relax to allow movement
• They also form the thick outer walls of hollow organs,
like blood vessels and digestive
Connective Tissue Cells
• Provide structural strength to the body
• Bone, cartilage, fat
• Defend against foreign invaders like bacteria.
• White blood cells
Tissues
• A tissue is a group of similar cells that perform
the same function. E.g muscle tissue, nerve
tissue
What is an Organ?
 An organ is made up of different types of
tissues that work together
E.g. heart, brain stomach
What are the five most important organs in the human
body?
• The brain
• The heart
• The lungs
• The liver
• The kidneys
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What is an Organ System?
An organ system is made up of several organs
that work together to perform a particular
function.
E.g. the digestive system
LEARNING ABOUT ORGAN SYSTEMS
How many body systems are in the human body?
11
16
Test Yourself: List the organ systems
• Integumentary
• Lymphatic
• Skeletal
• Respiratory
• Muscular
• Digestive
• Nervous
• Urinary
• Endocrine
• Reproductive
• Cardiovascular
The Digestive System
• Breaks down / digests food
• Organs include the stomach, pancreas, intestines, liver, gall
bladder
• Substances present include:
• Partially digested food, digestive juices, enzymes,
hydrochloric acid, feces, gases
Salivary glands
Oesophagus
Stomach
Liver
Gall bladder
Pancreas
Small intestine
Rectum
Large intestine
(colon)
Anus
What happens in digestive tract after death?
• The location and state of partially digested food in the digestive tract gives an
indication of the time of their last meal
• Enzymes and bacteria present begin to breakdown cells and tissues (autolysis)
• Bacteria expel gases like methane and ammonia that create the bloating
frequently seen in the abdomen after death.
• Any partially digested food in stomach and intestines and feces is removed
The Cardiovascular /Circulatory System
• Transports substances around the body
The Heart
• The pump of the system
• Made of CARDIAC
muscle
• Is made up of FOUR
chambers
The Blood
• Blood is a constantly flowing transport medium (fluid)
• Contains dissolved substances that provide the body
with nutrition, oxygen, hormones, water
• Helps with waste removal and control of body
temperature
What is the approximate volume of blood in an adult
human?
• 1.2 – 1.5 gallons / 5 litres
Livor mortis
• Livor mortis is the gravitational settling of blood which is no longer
being pumped through the body after death
• Damaged blood cells begin to spill out of broken vessels and, aided by
gravity, settle in the capillaries and small veins,
• Causes a bluish-purple discoloration of the skin
• Sets in 20- 30 minutes after death
Blood Vessels
ARTERIES
• Takes blood from •
heart to body
•
• Have thick,
muscular walls
•
• Have a narrow
lumen
•
VEINS
Brings blood from
body back to heart
Have thinner walls
than arteries
Have a wide
lumen
Have valves
CAPILLARIES
• Brings blood with
nutrients, oxygen,
water directly to
body cells and
tissues
• Walls are very
thin. Only 1 cell
thin.
Test Yourself
VEIN
CAPILLARY
ARTERY
Major Arteries and Veins
Body part/organ
Brain
Heart
lungs
Liver
Arms
stomach
intestines
kidneys
legs
Artery
Carotid artery
Coronary artery
Pulmonary artery
Hepatic artery
Subclavian artery
Celiac artery
Mesenteric artery
Renal artery
Iliac artery
Vein
Jugular vein
Coronary vein
Pulmonary vein
Hepatic vein,
Subclavian vein
Hepatic portal vein
Hepatic portal vein
Renal vein
Iliac vein
The Cardiovascular system and the Embalming
Process
• The act of pumping arterial embalming fluid into arteries
forces the person's blood out through the venous system
• Embalming fluid pumped through carotid artery or iliac
artery
• Embalming machine acts like the heart to push fluid through
all the blood vessels to all of the tissues
The Respiratory System
• Allows breathing. Brings oxygen into the body and gets rid of
carbon dioxide
• Includes organs like the
• Lungs
• Trachea
• Bronchi
Pharynx
Epiglottis
Right lung
Larynx
Trachea
Left bronchus
Left lung
Diaphragm
Integumentary System
• The integumentary system is the
largest organ of the body that
forms a physical barrier between
the external environment and the
internal environment
• Includes:
• The skin
• Hair
• Glands
• Nails
• Nerves and blood vessels
Functions of the skin
• Physical, water proof barrier against pathogens
• Temperature control
• Excretion of wastes
• Sensation
The Skin
• Has three layers
• Epidermis (top layer)
• Dermis: glands, hair
follicles
• Subcutaneous (fat) layer
Skin Slippage
• Skin slippage is a part of the decomposition process
when the top layers of skin become disconnected
from layers below
The Muscular System
• The muscular system is an organ system consisting of skeletal, smooth, and
cardiac muscle.
• Permits movement of the body,
• Maintains posture,
• Circulates blood throughout the body.
• Controlled by the nervous system although some muscles can be completely
autonomous.
Rigor mortis
• Stiffening of the joints and muscles of a body a few hours
after death,
• Usually lasts from one to four days.
• Body relaxes again once muscle tissue breaks down
Rigor mortis
• In life, muscle cells contract and relax due to the actions of two
proteins (actin and myosin), which slide along each other.
• After death, the cells are depleted of their energy source and
the protein filaments become locked in place.
• This causes the muscles to become rigid and locks the joints.
The Skeletal System
• Allows movement and support of the body
• Protects organs
• Makes red blood cells
• Includes organs like the
• Bones
• Cartilage
• Tendons
• Ligaments
• Joints
The Reproductive System
• Produces offspring
• Includes organs like the
• Penis
• Testes
• Ovaries
• Uterus
The Urinary System
• Filters the blood and removes metabolic wastes
• Produces urine
• Includes organs like the
• kidneys
• bladder
The Nervous System
• Controls the activities of the body
• Includes organs like the
• Brain
• Spinal cord
• Nerves
The Endocrine System
• Made up of hormone producing glands
• Hormones control
• metabolism,
• growth
• sexual development.
The Lymphatic System
The lymphatic system has three main parts:
• The lymphatic vessels: the tubes along which the lymph
flows. Resembles veins
• The lymph: the fluid
• The lymph nodes: to clean the lymph
Functions of the Lymphatic System
• Drains tissue fluid from cells and tissues as lymph
• Returns clean fluid back to the blood
• The lymph vessels return the fluid to the bloodstream
through the subclavian vein in the upper arm and neck
THE END