Understanding the basic anatomy and physiology of the human body
Glossary 2
The organisation of the body 4
Internal cavities 5
Regions 6
Cells, tissues, organs and systems 6
The cardiovascular system 13
Heart 14
Blood vessels 16
Blood 18
The flow of blood through the heart 21
Pulse 23
The respiratory system 25
Structure 25
Function 26
The musculoskeletal system 29
Function 29
The skeletal system 29
The muscular system 33
The nervous system 38
Function 38
Structure 38
Central nervous system 39
Peripheral system 42
The sensory organs 44
Integumentary system 46
Structure 46
Function 46
Digestive system 48
Structure 48
Function 51
The urinary system 53
Structure 53
Function 54
The reproductive system 56
The female reproductive system 56
Male reproductive system 57
Endocrine system 59
The immune and the lymphatic system 62
Structure of the immune system 62
Function of the immune system 62
Structure of the lymphatic system 63
Function of the lymphatic system 63
Resources 64
Texts 64
Websites 65
Feedback 67
The human body is an amazing feat of biological architecture. It is designed to not only ensure its own survival, but the survival of the human species. The study of the human body is divided into two sections called anatomy and physiology. Anatomy is the study of the structure or parts that make up the body, whilst the physiology is concerned with their function.
Glossary
Anatomy
The study of body structures and their relationships to one another.
Physiology
The study of the functions of cells, tissues and organs of the living organism.
Histology
The study of the microscopic structure of tissue.
Pathology
The study of the nature and cause of disease which involves changes in structure and function.
Microbiology
The scientific study of microorganisms.
Pharmacology
The study of drugs or substances and their origin, nature, properties and effects upon living organisms.
The organisation of the body
The human body is organised into various levels that begin at the very small and basic and come together to form the complete body whose different parts work in unison. This can be seen as a kind of ‘ladder’ going from the basic to the very complex.
At the simplest level, the body is comprised of atoms.
Atoms to the human body
Activity 1
In this activity you will learn about the organisation of the body. Write the name of the level next to the picture. Choose from the following words:
Tissue level / Organ level / Human bodyChemical level / Cellular level / System level
See the end of the topic for feedback
Internal cavities
The body has two (2) sets of internal cavities that provide different degrees of protection to the organs that lie within them. These are the:
1 Dorsal cavity that encases the brain and the spine.
2 Ventral cavity which comprises the thorax (chest) – this encases the heart and the lungs and the abdominopelvic cavity which encases our abdominal organs and those of our reproductive system.
Regions
The body is also divided into regions. Examples of these include the:
· Epigastric region — which lies below the bottom of the breastbone and above the umbilicus (belly button).
· Inguinal region — which lies within the groin.
· The cervical region — which lies at the back of the neck.
· The gluteal region — which lies in the area of the buttocks.
Cells, tissues, organs and systems
The cell
The basic unit of body structure is the cell. All cells need food, water, and oxygen to live and function. As cells use or metabolise food and oxygen they give off carbon dioxide and other wastes. The cell is comprised of the cell membrane, which is the outer covering; it encloses the cell and helps it hold its shape.
The nucleus is the control centre; it directs the cell’s activities. Cytoplasm surrounds the nucleus. Organelles are structures that are suspended in the cytoplasm. The protoplasm refers to all structures, substances and water within the cell.
Chromosomes are threadlike structures within the nucleus. Each cell has 46 chromosomes. Chromosomes contain genes, which determine our physical and chemical makeup. (Sorrentino, 1997)
Here are the most common parts of the cell
Parts of the cell
Cell qualities
· The cell is the most basic unit of life.
· There are cells that are organisms themselves, such as bacteria cells.
· There are cells that only function when part of a larger organism.
· In the body, there are brain cells, skin cells, liver cells, blood cells and many more.
· All of these cells have unique functions and features.
Although cells may be very different and highly specialised, they all have the same basic structure. They all have:
· an outer covering called the membrane
· a main substance called the cytoplasm
· a control centre known as the nucleus
· organelles dispersed within their cytoplasm.
The cell membrane protects the cell and regulates the passage of materials into and out of the cell.
The nucleus is the control centre of the cell. DNA, which makes up the genes, is found within the chromatin granules and within the nucleolus is the RNA.
Organelles, which are structures found in the cytoplasm, are the:
· mitochondria, the “powerhouse” of the cell, function in cellular metabolism and respiration
· endoplasmic reticulum produces proteins and lipids and transports these substances within the cell
· lysosomes function in intracellular digestion and form the “self-destruct” system of the cell
· golgi complex concentrates some secretions, adds carbohydrates to some secretions and packages secretions for export from the cell
· vacuoles are small cavities within the cell used to store secretions or waste products
· centrioles, cilia and flagella are composed of microtubules
o centrioles are contained in the centrosome and are involved in mitosis (cell division)
o cilia aid in the movement of materials outside the cell. For example, trapping of dust particles in the respiratory tract.
o flagella are important in the locomotion of sperm cells.
Functions of the cell
1 Respiration — all cells require oxygen to metabolise food.
2 Ingestion and assimilation — cells are able to select chemicals from the surrounding fluid for their structure.
3 Growth and repair — cells can synthesise new cytoplasm so that growth can occur and repair worn out parts.
4 Excretion — waste products are eliminated into surrounding tissue to be transported by the blood for elimination via organs.
5 Irritability and activity — cells are able to respond to stimuli. For example a stimulus causes a muscle to contract or relax.
6 Metabolism — cells are able to break down and use substances from food as fuel.
7 Reproduction — cells reproduce by simple division but some cells can never be replaced once destroyed. For example, central nervous system cells.
Activity 2
In this activity you will learn about the structure and function of cells. Draw a line from the structure to the correct function
Structure / FunctionIngestion and assimilation / Cells are able to break down and use substances from food as fuel
Irritability and activity / Cells can synthesise new cytoplasm so that growth can occur and repair worn out parts
Respiration / Waste products are eliminated into surrounding tissue to be transported by the blood for elimination via organs
Metabolism / Cells are able to select chemicals from the surrounding fluid for their structure
Excretion / Cells reproduce by simple division but some cells can never be replaced once destroyed eg. Central nervous system cells
Growth and repair / All cells require oxygen to metabolise (process) food
Reproduction / Cells are able to respond to stimuli for example, a stimulus causes a muscle to contract or relax
See the end of the topic for feedback
Tissues
Groups of cells form tissues and there are four main types. The structure of tissues reflects their function.
Types / Function / ExampleEpithelial / Protection / Skin
Connective / Support / Bones
Muscular / Movement / Skeletal
Nervous / Communication / Brain
Epithelial tissue
This tissue covers the body surfaces and lines its cavities. Some specialise to form glands.
The functions of epithelial tissue include:
· protection
· absorption
· secretion
· excretion
· surface transport
· reception of sensory information.
A gland is one or more epithelial cells specialised to produce and discharge substances.
Endocrine glands secrete have no ducts and secrete hormones directly into the bloodstream, for example pituitary gland.
Exocrine glands release their secretions through ducts, for example salivary and sweat glands.
Connective tissue
This tissue joins other tissues of the body together, supports the body and protects underlying organs.
Some main types are:
· ordinary connective tissue - subcutaneous tissue and collagen
· adipose tissue - stores fat
· cartilage - protects joints and supports soft tissues
· bone - rigid supporting tissue of the skeleton
· blood - lymph and lymphoid tissue - produce blood cells
Muscular tissue
Muscle is composed of cells specialised to contract.
Skeletal muscle is striated (striped) and is under voluntary control.
Cardiac muscle is present only in the walls of the heart, is striated and is controlled by involuntary nerve messages from the brain.
Smooth muscle, also involuntary, is responsible for movement of food through the digestive tract, and changing the diameter of blood vessels.
Nervous tissue
Nervous tissue forms the brain, spinal cord and the nerves. The basic cell is called the neuron.
Specialised to receive stimuli and send impulses from one part of the body to another.
Organs
Groups of tissues come together to form organs. For example the heart is made up of cardiac muscle and nervous tissues, held together with connective tissues and lined with epithelium. Each organ has a specific function.
Organ / FunctionHeart / Circulation
Stomach / Digestion
Brain / Communication/coordination
Uterus / Reproduction
Systems
Several organs working together form a system. For example the urinary system is made up of the kidneys, bladder and ureters.
System / OrgansCardiovascular / Heart, blood, vessels
Respiratory / Nose, pharynx, trachea, bronchus, bronchiole, lungs, alveoli
Musculoskeletal / Muscles, joints, bones
Integumentary / Skin
Nervous / Brain, spinal chord, nerves
Digestive / Tongue, oesophagus, stomach, liver, pancreas, gall bladder, small intestine, large intestine, rectum, anus
Urinary / Kidneys, ureters, bladder, urethra
Reproductive / Male: Testes, scrotum, vas deferens, seminal vesicle, prostate, ejaculatory duct, urethra, penis, glans, perineum
Female: Ovaries, fallopian tubes, uterus, cervix, vagina, labia, urethra, clitoris, perineum
Endocrine / Glands: pituitary, hypothalamus, pineal, parathyroid, thyroid, adrenals, pancreas, gonads: ovaries ♀; testes ♂, and their hormones.
Lymphatic/Immune / Lymph glands and vessels, lymph, lymphocytes, T and B cells.
Activity 3
In this activity you will revise the functions of the different body systems.
Match the body system listed in Column 1 to the correct group of organs in Column 2. Write the letter next to the body system.
Column 1 / Column2____ Integumentary. / A. Heart, vessels, blood.
____ Cardiovascular. / B. Trachea, bronchus, lungs.
____ Nervous. / C. Brain, spinal chord
____ Urinary. / D. Skin
____ Reproductive. / E. Kidney, bladder
____ Digestive. / F. Glands, hormones
____ Lymphatic. / G. Lymph glands, vessels.
____ Respiratory. / H Ovaries, testes, uterus, penis
____ Musculoskeletal / I. Mouth, oesophagus, intestines, rectum
____ Endocrine. / J. Muscles, bones
See the end of the topic for feedback
The cardiovascular system
The cardiovascular system is one of the major body systems. It transports oxygen, carbon dioxide, waste products, nutrients and hormones to and from various parts of the body.
The cardiovascular system is made up of the heart, the blood vessels (arteries and veins and capillaries) and blood. The heart has major vessels that supply it with deoxygenated blood (travels back to the heart from the body), and major vessels that carry oxygenated blood away from the heart to all the parts of the body.
The major vessels that carry blood to and from the heart are:
· inferior vena cava conveys deoxygenated blood (blood low in oxygen) from the lower extremities of the body to the heart
· superior vena cava coveys deoxygenated blood from the upper extremities of the body to the heart
· aorta conveys oxygenated blood (blood high in oxygen) away from the heart
This information is important so that you can gain an understanding of how the heart works and some of the conditions that may affect the functioning of the heart.
Location of the heart and the major vessels that supply blood to the heart
Heart
The heart is a hollow organ about the size of a fist and is composed of special muscle tissue (cardiac muscle). It lies under the breast bone in the centre of the cardiothoracic cavity. In the average lifetime the heart beats 250 million times and pumps 340 million litres of blood. The heart is a sophisticated pump that is controlled by an electrical current that is initiated in the brain.
The heart is divided into a left and right side by a muscular wall called the septum and has four chambers.
Heart chambers and valves
The chambers of the heart include the:
· right atrium which receives deoxygenated blood (low in oxygen) from all over the body
· right ventricle receives blood from the right atrium and sends it to the lungs via the pulmonary artery to become oxygenated and get rid of carbon dioxide
· left atrium receives oxygenated blood from the lungs and sends it to the left ventricle
· left ventricle receives blood from the left atrium and sends it out to the body via the aorta.
The heart wall consists of three layers - the endocardium is the inner lining, the myocardium is the muscle layer and the pericardium is the outer covering.
The chambers of the heart are separated by valves:
· tricuspid valve is located between the right atrium and right ventricle
· bicuspid (mitral) valve is located between the left atrium and left ventricle