BMS165 Topic 1: Major Anatomy

Anatomy – the study of the structure of body parts and their relationships to one another.

Physiology - the study of the function of the body’s structural machinery, often at the cellular or molecular level. Has multiple subdivisions, for example - renal physiology

Pathophysiology – The study of structural and functional changes in tissue and organs that lead to disease.

The Levels of Human Structure include:

• Chemical level: Atoms and molecules that make up the body.

• Cellular level: Cells, the basic unit of life, that perform various functions.

• Tissue level: Groups of similar cells working together to perform a specific function.

• Organ level: Structures composed of two or more types of tissues that work together to perform complex functions.

• Organ system level: Groups of organs that work together to carry out a broad function.

• Organismal level: The complete living entity that can function independently.

Organ Systems

• An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body

• The human body has 11 organ systems and (or plus) an immune system.

• The immune system is better described as a population of cells that inhabit multiple organs rather than as an organ system.

The Eleven Organ Systems

• Integumentary System: Protects the body from external damage and pathogens, regulates temperature, and provides sensory information.

• Skeletal System: Provides structure to the body, protects internal organs, facilitates movement through the attachment of muscles, and stores minerals such as calcium and phosphorus.

• Muscular System: Enables movement of the body and maintains posture through the contraction of muscles, while also generating heat.

• Nervous System: Coordinates and controls body activities by transmitting signals between different parts of the body, processing sensory information, and facilitating communication among various systems.

• Endocrine System: Regulates bodily functions through the release of hormones, which control processes such as metabolism, growth, and reproduction.

• Cardiovascular System: Responsible for transporting blood, nutrients, oxygen, carbon dioxide, and hormones throughout the body, thereby playing a crucial role in maintaining homeostasis.

• Lymphatic System: A network of tissues and organs that helps rid the body of toxins, waste, and other unwanted materials, while also playing a key role in immune function by transporting lymph, a fluid containing infection-fighting white blood cells.

• Respiratory System: Facilitates the exchange of gases, primarily oxygen and carbon dioxide, between the body and the environment, ensuring that oxygen is delivered to tissues and carbon dioxide is expelled.

• Digestive System: Responsible for breaking down food into nutrients, which are then absorbed into the bloodstream, while also eliminating waste products, thus playing a vital role in energy production and overall health.

• Urinary System: The urinary system is responsible for filtering blood to create urine, which removes waste products and excess substances from the body, thereby maintaining fluid and electrolyte balance, as well as regulating blood pressure.

• Male Reproductive System: Involved in the production of sperm and hormones, the male reproductive system plays a crucial role in sexual reproduction and the maintenance of male secondary sexual characteristics.

• Female Reproductive System: The female reproductive system is essential for ovum production, hormone regulation, and providing the necessary environment for fertilisation and fetal development, thus playing a key role in sexual reproduction and the continuation of species.

Anatomical Variation - The variation in position, number or structure of a particular organ or body part.

Homeostasis

• When you think about the fact that your body contains tril­lions of cells in nearly constant activity, and that remarkably little usually goes wrong with it, you begin to appreciate what a marvellous machine your body is.

• Homeostasis is the body’s ability to maintain relatively stable internal conditions even though the outside world changes continuously.

• Although the literal translation of homeostasis is “unchang­ing,” the term does not really mean a static, or unchanging, state. Rather, it indicates a dynamic state of equilibrium, or a balance, in which internal conditions vary, but always within relatively narrow limits.

• In general, the body is in homeosta­sis when its needs are adequately met and it is functioning smoothly.

Two types of homeostatic feedback loops

Negative Feedback Loops:

• Occur in biology when the product of a reaction leads to a decrease in that reaction

• In this way, a negative feedback loop brings a system closer to a target of stability or homeostasis

• Negative feedback loops are responsible for the stabilization of a system, and ensure the maintenance of a steady, stable state

Positive Feedback Loops:

• Occur in nature when the product of a reaction leads to an increase in that reaction.

• If we look at a system in homeostasis, a positive feedback loop moves a system further away from the target of equilibrium

• It does this by amplifying the effects of a product or event and occurs when something needs to happen quickly

Homostatic Control Mechanisms

The following 3 homeostatic control mechanisms aid in preventing homeostatic imbalances:

• Receptor – type of sensor that monitors the environment and responds to stimuli that produce imbalances in homeostasis (e.g., hormones, free nerve endings)

• Control Centre – determines the set point at which the variable is maintained. Analyses input from receptor and determines response (brain, spinal cord)

• Effector – provides the means for the Control Centre’s response to the original stimulus (smooth muscle, skeletal muscle, cardiac muscle or glands)