LEARN MORE ABOUT HUMAN PHYSIOLOGY
|Number of Assignments
A course designed for health therapists and all those working in health care that want or need to develop a deeper understanding of the human body processes and health maintenance.
There are 9 lessons in this module as follows:
1. Cellular Physiology
- Membrane transport
- Simple passive transport
- Facilitated passive transport
- Active transport
- Transcription, translation and post transcriptional modification
- Cellular metabolism
- Cellular energy production
- Homeostatic balance
- Feedback system
- Body temperature
- Effect of temperature on enzymes
- Adenosine triphosphate
- Physiology of tissue
- Epithelial tissue
- Connective tissue
- Dense connective tissue
- Bone tissue
- Bone physiology
- Compact bone
- Spongy bone
- Muscle tissue
- Muscle fibre: filament types
- Nervous tissue
3. Systems Physiology
- Central and peripheral nervous systems
- Somatic and autonomic nervous systems
- Sensory, motor and integrated systems
- General senses
- The process of sensation
- Special senses
- Autonomic nervous system
- Autonomic reflexes
- Parasympathetic nervous system
- Sympathetic nervous system
- Structure of the nervous system
- Parts of a neuron
- Classification of different neurons
- Neuron function
- Action potentials
- Graded potentials
- Synapses: electrical, chemical
- Neural circuits
- Different functions of the brain
- Homeostatic reflex arc
- Spinal chord and spinal nerves
- Functions of endocrine system
- Actions of hormones
- Hormone target cells
- Anterior pituitary gland hormones
- Actions of posterior pituitary
- Actions of adrenal gland: cortex and medulla
- Pancreatic hormones
- Thyroid gland
- Adrenal glands
- Hormone receptors
6. Cardiovascular Physiology
- Heart function
- Cardiac cycle
- Heart muscle cell contraction
- Blood vessels
- Blood: regulation, erythrocyte physiology, leucocytes
- Lymphatic system
- Blood flow
- Gas transport
- Arterial alveolar gradient
- Oxygen transport
- Factors affecting oxygen release by haemoglobin
- Immune system structure
- Lymphatic organs and tissues
- Types of resistance
- Non specific cellular and chemical defences: phagocytes, natural killer cells
- The inflammatory response
- Specific defence mechanisms
- Humoral immunity
8. Respiratory Physiology
- Respiratory epithelium
- The lungs
- Airway anatomy
- Nasal and oral cavities
- Larynx, trachea, bronchial tree
- Function of respiratory system
- Pulmonary ventilation
- Lung volumes and capacity
9. Renal Physiology
- Urinary system
- Blood and nerve supply
- Nephrons Kidney functions
- Renal processes
- Glomerular filtration
- Electrolyte and Acid base balance
- Tubular reabsorption
- Tubular secretion
- Urinary bladder
- Micturition process
LEARN ABOUT THE VARIOUS SYSTEMS THAT TOGETHER CAUSE A BODY TO FUNCTION
The human body is a very complex thing; made up of many different functioning systems, all interacting with each other to support the entire organism, maintaining and operating it's component parts to achieve an overall function. In many respects, the systems within a body are like the parts of a machine such as a car - if one fails, it impacts on the rest.
The Lymphatic System
The lymphatic system is an example of one of these component parts in a human body. Lymphatic organs and tissues are classified into two groups – primary and lymphatic organs where the stem cells divide and become immunocompetent (red bone marrow and the thymus) and secondary lymphatic organs and tissues which are sites where the most immune responses happen (Lymph nodes, spleen and lymphatic nodules or follicles).
The Immune System is responsible for the following activities:
- Immunity as in defence against pathogens. Pathogens are foreign, disease-causing organisms such as viruses and bacteria.
- Maintenance of fluid balance in the internal environment. Plasma filters into interstitial spaces from blood flowing through the capillaries. Most of this fluid is absorbed by tissue cells or reabsorbed by blood The lymphatic vessels act as a drain to collect the excess
- Removal of old cells and tissue debris (after damage or disease).
- Identification and destruction of abnormal or mutant cells (e.g. cancer).
- Inappropriate immune responses that lead to allergies.
- Rejection of tissue cells of foreign origin (e.g. transplantations).
A person’s immune system protects the body from intruders: bacteria, viruses, parasites, cancer cells, etc. We have both non-specific and specific defence mechanisms to fight invaders. To maintain homeostasis, the body must continually combat against harmful agents in our internal and external environment. Although we are subjected to different microbes that produce disease, most of the time we are able to fight them off and remain healthy. This is due to the body’s ability to develop a resistance, which is the warding off damage or disease through our defences.
Types of Resistance
The body has two general types of resistance, specific resistance system, also known as defence mechanisms or non specific resistance mechanisms.
Non-specific immunity is a general response to a variety of pathogens (skin and mucous membranes, production of antimicrobial substances, natural killer cells, phagocytosis, inflammation, and fever) Non-specific defence mechanisms work against a wide variety of invaders. These defence mechanisms include the barrier formed by our skin; chemicals in perspiration, skin oil, saliva, tears, etc.; the hairs in our nostrils; the ciliary escalator (the cilia and mucus that clean out dust and debris from our lungs and trachea) in our respiratory tracts; the inflammatory response which is the dilation of blood vessels and accumulation of WBCs at the site of an injury (the signs of which are that the area is red, hot, and swollen); and fever, a raised body temperature to inhibit the growth of pathogens. Note that a fever is caused by your body to inhibit the growth of bacteria, etc., not by the “germs” themselves, per se.
Surface Membrane Barriers
The skin and mucous membranes are the first line of defence of the body as a mechanical barrier to pathogens or disease causing organisms. There is also a chemical line of defence in the form of sebum, perspiration, and gastric juices. Transferrins (chemicals that discourage bacterial growth) are found in the blood and interstitial fluid, and provide a second line of defence. The skins secretions are very acidic with a pH balance of 3-5 in general which helps to stop bacterial forming. Vaginal secretions are also very acidic. The mucosa of the stomach secretes hydrochloric acid to kill any pathogens that may be in food, and the respiratory tract protects the lungs with cilia to sweep bacteria and dust upwards towards the mouth. Even saliva contains lysozyme with is an enzyme which destroys bacteria.
Non Specific Cellular and Chemical Defences
There are a variety of nonspecific processes that the body will use to protect itself from pathogens. Some mechanisms include inactive proteins in the blood and on cell membranes that when activated enhance certain immune reactions such as inflammation. Natural killer cells and phagocytosis have the ability to combat a wide variety of infectious microbes. They may release chemicals like the NK cells or they may ingest the microbe as in phagocytosis. Fever is also considered a non specific reaction.
These cells are white blood cells that find waste material, toxins or other harmful material in the blood stream and engulf and attack the foreign object. The main phagocytes are called macrophages – these are found in nearly every organ and roam through tissue spaces looking for waste matter. Neutrophils form the largest amount of white blood cells and also become phagocytic on infectious matter.
Natural Killer Cells
These cells are another type of lymphocyte that contain granules filled with chemicals. They are a unique group which circulate the blood and lymph. This type of cell is known as ‘natural killers’ because they do not need to recognise a specific virus- infected or cancerous cell like the other lymphocytes – natural killer cells seek out and destroy any cancerous or infectious cells. There killing activity is therefore non specific.
When the body cells do become infected with a virus, they produce proteins called interferon (IFN). IFN then diffuses to un-infected nearby cells and binds to surface receptors and make anti-viral proteins.
The Inflammatory Response
Inflammation is the body’s second line of defence and is triggered whenever body tissues are injured or when cells are damaged or affected by microbes.
- Once the body is injured, chemical are released into intracellular fluid – these can be phagocytes, lymphocytes, mast cells and blood proteins such as histamine, prostoglandins and lymphokines
- The chemicals also increase capillary permeability around the area, allowing larger immune cells to pass through
- Exudate which consists of fluid and protein containing clotting agents and antibodies seeps into the surrounding tissues causing swelling
- This swelling pushes on nerve endings and creates pain in combination with lack of nutrients and bacterial toxins in the injured area. Release prostoglandins can also cause pain
- Blood circulation is increased around the damaged area of the body, regardless of what that area or type of damage may be. This dilates blood vessels which allows for increased blood flow and thus strengthen the immune presence.
- Protective leucocytes enter the are
- Fibrin walls off the area and tissue repair begins
The four cardinal symptoms of inflammation are:
Fever is classified as an abnormally high body temperature which is the body’s systemic response to invading microorganisms. It is not an illness but the sign of an illness. Generally, the body temperature is regulated by the hypothalamus which is set at approximately 37 degrees. Pyrogens are the substances that cause fever – they are secreted usually by macrophages exposed to bacteria and other foreign substances in the body. When the hypothalamus is activated, the temperature of the body rises by blood being shunted from the skin to the interior of the body – thus reducing heat loss. Shivering also increases the production of heat through muscle contractions. The elevated temperature will stimulate the defensive actions of the body and repair processes. Fevers are not always caused by infection, however they can be caused by inflammation, cancer or allergic reactions.