1. An introductory to Human Body

Anatomy & Physiology

Anatomy structure: Human anatomy is the scientific study of the body’s structures.

Physiology - Functions: Human physiology is the scientific study of the chemistry and physics of the structures of the body and the ways in which they work together to support the functions of life.

Subspecialties of Anatomy & Physiology

Cell biology: cellular structure & functions

Histology: Microscopic structure of tissues.

Surface anatomy: surface marking of the body to understand internal anatomy through visualization and palpation (gentle touch)

Gross anatomy: a structure that can be examined without using a microscope.

Pathological anatomy: structural changes (from gross to microscopic) associated with the disease.

The Levels of Organization

Atoms → Molecule → Cells → Tissues → Organs → Organisms 

 

• Atoms: the simplest unit of subatomic particles.
• Molecular: the chemical building blocks of body structure. (2 or more atoms)
• Cells: the smallest independently functioning unit of living organisms.
• Tissues: a group of many similar cells (through sometimes composed of a few related types) that work (e.g. Epithelial, Muscle, Nerves, etc
• Organs: an anatomically distinct structure of the body composed of 2 or more tissue types. Heart, Stomach, gonads.
• Organ System: A group of organs that work together to perform major functions. (e.g. Cardiovascular, Respiratory, Reproductive, Endocrine System, etc).
• Organisms: the highest level of organization.
• Biosphere

8 Characteristics of Human Life

1. Organization: A human body consists of trillions of cells organized in a way that maintains distinct internal compartments.
A variety of cell membrane keeps the intracellular environment (the fluids & organelles inside) from the extracellular environment.

 

2. Metabolism:

Metabolism is the sum of all Anabolism & Catabolism reactions that take place in the body.
Basic function as an organism is to consume (ingest) energy & molecules in the foods you eat, convert some into fuel for movement, sustain body functions & build & maintain body structures.
Every cell in the body makes use of a chemical compound, adenosine triphosphate (ATP), to store & release energy. Anabolism 

Anabolism: Anabolism is the process whereby smaller, simpler molecules are combined into larger, more complex substances.
Absorb energy, ATP 

 

Catabolism: Catabolism is the process by which larger more complex substances are broken down into smaller simpler molecules Release energy, ATP 

 

3. Responsiveness
Responsiveness is the ability of an organism to adjust to changes in its internal & external environments.

 

4. Movement The human body is coordinating the action of the entire muscle groups to enable you to move air into & out of your lungs, to push blood throughout your body. & contract skeletal muscle to move the bones of the skeleton to get from one place to another.

 

5. Development
All the changes the body goes through in life. The development includes the process of differentiation, in which unspecialized cells become specialized in structure & function to perform certain tasks in the body.

 

6. Growth
With the increase in body size, all multicellular organisms, grow by increasing the number of existing cells.

 

7. Reproduction
The formation of a new organism from parent organisms.

 

8. HomeostasisThe human body maintains a relatively constant internal environment. To create optimal conditions for the chemical reactions of metabolism.  e.g. body temperature, PH, Blood nutrient concentration, blood pressure

 

Setpoint is the restricted set of value around which the normal range fluctuate / optimal level (preferred level) for us (e.g. T: 37℃Range (Normal Range) is the restricted set of values that is optimally healthful & stable/deviation from set point that allows normal function.

Negative feedback system is the mechanism that reverses a deviation from the set point which regulates homeostasis. Receptor (Sensor) → Control Center → Effector

 

Example. Heat loss

Stimulus: body temperature exceeds 37℃ 

Receptor (Sensor): Nerve cells in skin & brain
Control Center: Temperature regulatory center in the brain
Effector: sweat glands throughout body and sweat evaporate from the skin surface into the surrounding air, it takes heat with it, blood vessels in the skin begin to dilate allowing more blood from the body core to flow the surface of the skin increases. Depth of respiration increases & a person may breathe through an open mouth instead of through the nasal passageways. This further increases heat loss from the lungs.

 

Positive feedback
A change in the body’s physiological condition rather than reversing it. A deviation from the normal range results in more change and the system moves further away the normal range.

 

Example: Childbirth
Stimulus: the first contraction of labor pushes the baby toward the cervix
Sensor: Nerve impulses from the cervix transmitted to the brain
Control Centre: Brain stimulates the pituitary gland to secrete oxytocin

Effector: Oxytocin causes stimulates uterine contractions & pushes the baby towards the cervix
The cycle of stretching, oxytocin release, and increasingly more forceful contractions stops only when the baby is born.

Anatomical Terminology

• Anatomical position: the body standing upright, with the feet at shoulder width and parallel, toes forward. The upper limbs are held out to each side and the palms of hands face forward.
  
• Prone: face-down orientation
  
• Supine: face-up orientation

Directional Terms 

• Anterior (or ventral): the front or direction toward the front of the body 
• Posterior (or dorsal): the back or direction toward the back of the body.
• Superior (or cranial): a position above or higher than another part of the body proper.
• Inferior (or caudal): a position below or lower than another part of the body proper.
• Lateral: the side or direction toward the side of the body.
  
• Medial: the middle or direction toward the middle of the body
• Proximal: a position in a limb that is nearer to the point of attachment to the trunk of the body.
• Distal: a position in a limb that is farther from the point of attachment or the trunk of the body.
  
• Superficial: a position closer to the surface of the body.
• Deep: a position farther from the surface of the body.
  

Body Planes 

There are 3 planes commonly referred to in anatomy and medicine.

• Sagittal plane: plane divides the body or an organ vertically into the right & left sides.
• Frontal plane (coronal plane): plane divides the body or an organ into an anterior (front) portion & a posterior (rear) portion.
• Transverse Plane: a plane that divides the body or organ horizontally into upper & lower portions.

Body Cavities 

 

• Ventral (anterior) cavity
  Thoracic cavity: contains lungs & heart (heart locates in the mediastinum), The diaphragm forms the floor of the thoracic cavity & separates it from the more inferior abdominopelvic cavity.
• The abdominopelvic cavity: The largest cavity in the body. No membrane physically divides the abdominopelvic cavity, it can be useful to distinguish between the abdominal cavity, the division that houses the digestive organs, and the pelvic cavity, the division the houses the organs of reproduction.
• Dorsal (posterior) cavity
  Cranial cavity: Houses the brain & the spinal cavity encloses the spinal cord.

Membranes of the anterior (ventral) Body Cavity

• Serous membrane (also referred to as a serosa):  thin membranes that cover the walls & organs in the thoracic & abdominopelvic cavities.
  
• Parietal layers of the membranes line the walls of the body cavity
  
• The visceral layer of the membrane covers the organs (the viscera).Between the parietal & visceral layers is a very thin, fluid-filled serous space, or cavity. 

 

Pleura: the serous membrane that surrounds the lungs in the pleural cavity

The pericardium is the serous membrane that surrounds several organs when they move, such as when the lungs inflate or the heartbeats

The peritoneum is the serous membrane that surrounds several organs in the abdominopelvic cavity.

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