Medical Physiology: An Overview of the Human Body

The human body is an amazing machine — of systems all interacting in harmony to keep man alive. How it works­—from the tiniest cell to the most intricate system in the body—is the territory of medical physiology. The scientific study of mechanical, physical, and biochemical properties of humans in good health is the domain of this science. For those in or planning to be in the healthcare field an understanding of medical physiology is essential.

This guide will help make the basic elements of medical physiology a little more comprehensible. We will investigate our most important systems upon which we rely for life and proper function, from the cellular level on up to the whole integrated being. But by the end, you’ll have a better sense of just how our bodies accomplish the amazing feat of daily existence — and why that knowledge is essential for modern medicine.

Cellular Physiology: The Basic Building Blocks

Every single process in the human body starts with its cells. The science of cellular physiology focuses on individual cells and how they function. These tiny machines are the building blocks of all life, each having its own set of specialised structures, known as organelles, to help it do its job.

• The Cell Membrane: This outside layer of the egg is a barrier that allows only certain things to enter or exit. It’s a lipid bilayer studded with proteins that help transport things across and communicate in and out.
• The Nucleus: Known as the cell’s “control center,” the nucleus contains our DNA — the blueprint for everything a cell does, from generating proteins to reproducing.
• Mitochondria: The cell’s “power plants,” mitochondria produce most of the cell’s supply of adenosine triphosphate (ATP), used as a source of chemical energy.
• Ribosomes and Endoplasmic Reticulum: Ribosomes and the endoplasmic reticulum collaborate to make, fold and modify those proteins — the doers of pretty much everything blooming at the cellular level.

If you want to understand how tissues and organs work, the first thing you must master is cell physiology. When cells fail to function properly, disease processes start, which is why research in this area is key to diagnosing and curing diseases.

Nervous System Physiology

Your nervous system is the master control center in your body, a complex network that connects all parts of the body and sends out messages. It includes the CNS, which is made up of the brain and spinal cord, and the PNS, which encompasses all other nerves.

Physiology here is concerned with how nerve cells, or neurons, generate and convey electrical signals known as action potentials. This system enables very effective long-distance communication.

• Central Nervous System (CNS): The brain perceives, acts, and sends signals to the rest of the body. The spinal cord serves as a superhighway for signals passing back and forth between the brain and the rest of the body, as well as controlling reflexes.
• Peripheral Nervous System (PNS): Extensions of the CNS to limbs and organs. It’s divided into the somatic system (which controls voluntary movements) and the autonomic system (which regulates involuntary activities like heartbeat and digestion). The autonomic system itself is divided into the sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) branches, working in opposition to each other to modulate homeostasis.

Cardiovascular Physiology

The blood circulatory system is made up of the heart. The vessels and blood, transport nutrients and oxygen (O2), hormones and waste.

• The Heart: This muscle is a double pump. The right side pushes deoxygenated blood to the lungs. And the left side pushes oxygen-rich blood out into the rest of the body. The series of systole (contraction) and diastole (relaxation) that occurs in the heart. Known as the cardiac cycle, are precisely orchestrated by an internal electrical conduction system.
• Vessels: Arteries move blood away from the heart, veins bring it back. And capillaries are small vessels that exchange materials between the blood and tissues. The physiology of blood vessels is to keep blood pressure within a healthy range while directing blood where it is most needed.
• Blood: This fluid connects all tissues and is composed of plasma, red cells (carry oxygen), white cells (fight infections), and platelets.

Cardiovascular physiology is a cornerstone of medicine, as diseases of this system are a leading cause of morbidity and mortality worldwide.

Respiratory System Physiology

The main job of the respiratory system is gas exchange, to move oxygen into the body and remove carbon dioxide. This is a crucial step for cellular respiration, which forms the energy that powers our cells.

The primary organs concerned with respiration are the lungs which work in conjunction with the diaphragm and other muscles to effect ventilation.

• Ventilation: The pumping of air into and out of the lungs.
• Gas Exchange:oxygen diffuses from the air into the blood, and carbon dioxide diffuses from the blood into the air where the body can exhale it.
• Carriage of Gas: Oxygen combines with hemoglobin in RBCs and transports the oxygen to tissue sites.

Respiratory physiology covers the neurological aspects of the rest and activity of other organ systems. In response to the body’s relaxing breathing and their arousal during a more strenuous exercise.

Renal Physiology: Kidney Function

The body naturally rids itself of toxins through the kidneys, the bodies’ plumbing system. Its function is much more than just urine production.

• Filtration and Excretion: The kidneys filter waste products from the blood to produce urine. Which is then excreted from the body.
• Maintaining Homeostasis: They perform a central role in controlling blood volume. Blood pressure and the balance of electrolytes (such as sodium and potassium) and pH in the blood.
• Hormone Production: Your kidneys make hormones that are critical to your well-being. Including erythropoietin (which stimulates red blood cell production) and renin (which regulates blood pressure)..

The functional unit of the kidney is the nephron. Where a complex process of filtration, reabsorption, and secretion takes place to finely tune the composition of the blood.

Endocrine System Physiology

The Endocrine System comprises a group of glands that produce hormones. Which are chemical substances that control various body functions. The endocrine system grants slow. Longer-lasting control compared to the rapid signals of the nervous system.

• Large Endocrine Organs: These are the pituitary, thyroid, adrenal, pancreas and gonads.
• Action of Hormones: After hormones circulate in the blood to target cells. They bind to specific receptors and cause an effect. This can influence growth, metabolism, mood and sexual function.
• Negative (and Positive) Feedback Loops: The endocrine system is controlled through positive and negative feedback systems. Based on the body’s need. To maintain homeostasis balance of various hormones in the blood.

The Integrated Human Body

Though we may concentrate on these systems one at a time. It’s important to recognise they don’t work in silos. Medical physiology focuses on the systems themselves. The nervous system sends rapid electrical signals, which direct immediate adjustments. A stable internal environment that need to be present for survival.

During a workout, for example, the respiratory system takes oxygen into the body as it works harder to demand more. The cardiovascular system pumps blood faster to get that oxygen quickly to muscles. And the endocrine system produces hormones like adrenaline that amp up performance. The renal system, meanwhile, contributes to controlling fluid balance as you sweat. It’s that beautiful, complex coordination that allows the human body to respond to an incredibly rich variety of challenges. A thorough understanding of this unity is what enables doctors to successfully treat and heal the human body.