Anatomy: Body Structure basics

Learning Objectives

• Understand the structure of the body
• Apply the anatomical terminology for use in body positions, regions, and planes
• Identify the terms clinical relevance for anesthesia practice

Body Structure

• The body is organized starting at chemicals and finishing at a whole organism
• The order of the most simple to most complex is: Chemicals -> Cells -> Tissue -> Organ -> Organ System -> Body as a whole

The Cell

• It's the functional unit of a living organism
• Metabolism is carried out by the cell
• They provide energy for metabolic reactions, and ATP
• Organelles are subunits of cells

What is an Organelle?

• Different structures inside a cell that have different jobs to complete
• Cell membrane helps keep fluids and other organelles inside the cell, acting as a security guard
• Small holes in the cell membrane allow some molecules in but keep harmful ones out
• Cytoplasm is the fluid that fills a cell
• Cytoplasm is made up of many dissolved molecules that can be used in processes, taking place throughout the cell
• Nucleus is a large membrane-bound, dark-staining organelle near the center of the cell, containing chromosomes
• Chromosomes are hereditary units, and direct all cellular activities
• There are 46 chromosomes in each human cell, except for the sex cells (sperm and ova)
• Nucleolus is inside the nucleus, is formed of RNA and proteins, and makes ribosomes
• Mitochondria are large organelles with internal folded membranes, known as the "powerhouse" of the cell
• They perform cellular respiration, and convert nutrients into ATP
• The Golgi apparatus is a layers of membranes that modify proteins, and sorts/prepares proteins for transport around the cell
• The Endoplasmic Reticulum is a network of membranes within the cytoplasm, with both rough and smooth variations
• Rough ER has ribosomes and modifies, folds, and sorts proteins
• Smooth ER participates in lipid synthesis
• Vesicles are small membrane-bound sacs in the cytoplasm that contain stored food and nutrients the cell needs to survive
• Ribosomes are small bodies that are free in the cytoplasm or attached to the ER, composed of RNA and protein, also known as the "protein builders"
• A Peroxisome digests nutrients and break down toxic materials
• A Lysosome digests and breaks down food in animal cells with the help of enzymes stored there
• Microtubules provide structure to the cell and help with cell division in animal cells
• Centrioles help cells divide during mitosis and meiosis, made up of microtubules in animal cells
• Cytology means science of cells and referring to baskets containing organelles and cytologists are scientists

Tissues

• Tissues are any group of cells that perform a single function
• The body has four types of tissue
• Epithelial tissue covers the internal and external body surfaces
• Connective tissue is a fibrous substance that holds and connects body parts together
• Adipose tissue, a form of connective tissue, stores fat; cartilage, also connective, protects and reinforces
• Bone, also Connective tisssue, makes up the skeleton
• Muscle tissue contracts and expands to allow the body to move freely
• Skeletal muscle moves the skeleton, the muscle has visible striations that produce contraction
• Cardiac muscle makes up the wall of the heart
• Smooth muscle makes up the walls of hollow organs, ducts, and vessels
• Nervous tissue carries messages to and from the brain and spinal cord to all parts of the body
• The functional cell of the nervous system is the neuron
• Neuron fibers can join to form nerves and create spinal cords, and the brain itself
• Histology is the branch of biology that studies the microscopic structure of tissue, and the Greek root of the word histology is histo-, or "anything that stands upright"
• A liver transplant requires a histocompatible donor organ to be compatible with the recipient

The Organs and the Organ Systems

• Cells -> Tissues -> Organs -> Systems
• Includes the digestive system, the muscular system, the integumentary system, the lymphatic system, the endocrine system, and the nervous system
• Also includes the skeletal system, the male and female reproductive systems, plus the respiratory and urinary systems, plus the circulatory system

Roots to Cells and Tissue

• Morph/o means form, example polymorphous
• Cyto, -Cytes means cell, example cytologist
• Nucle/o means nucleus, example nuclear
• Kary/o means nucleus, example karyotype
• Hist/o, hist/I means tissue, example histocompatibility
• Fibr/o means fiber, example fibrosis
• Reticul/o means network, example reticulum
• Aden/o means gland, example adenoma
• Papill/o means nipple, example papilla
• Muc/o means mucus, mucous membrane, example mucorrhea
• Karyotype genetic test is a type of genetic testing that look for size, shape and chromosome numbers in body cells
• Chromosomes are found in the cell nucleus
• Chromosomes contain genes that carry information called DNA, that controls characteristics of the body

Roots for Cell Activity

• Blast/o, -blast means immature cell, productive cell, embryonic cell, example histioblast
• Gen means origin, formation, example karyogenesis
• Phag/o means cat, ingest, example autophagy
• Phil means attract, absorb, example basophilic
• Plas means formation, molding, development, example hyperplasia
• Trop means act on, affect, example chronotropic
• Troph/o means feeding, growth, nourishment, example atrophy
• Hypertrophic Cardiomyopathy indicates thicker walls, and less blood to the heart

Directional Terms

• Inferior (or caudal) means "away from the head," or "lower/under"
• Superior (or cranial) means "toward the head end of the body" or "higher/above"
• Posterior (or dorsal) means "back of" or "behind/on the back"
• Anterior (or ventral) means "front of" or "in the front"
• Lateral = away from the midline (middle) of the body
• Medial = toward the midline (middle) of the body
• Intermediate = between two structures
• Proximal = nearest point of attachment to limb or structure
• Distal = farthest away from attachment or origin, this is also known as superficial for the surface of the body
• Some key directional terms
  • Anterior (ventral) -> Toward or at the front (belly) of the body
  • Posterior (dorsal) -> Toward or at the back (dorsum) of the body
  • Medial and lateral -> Toward the midline and toward the side of the body
  • Proximal/distal are nearer to the point of reference or farther

Planes of Division

• Planes of division
  • Frontal (coronal) plane, dividing the body into front and back
  • Sagittal (lateral) plane divides the body into left and right sides
  • Transverse (axial) plane that divides into left and right sides.
• Knowing the planes are helpful when looking at studies such as x-rays or computed tomography
• Magnetic resonance images are used for coronal, axial(transverse plane), and sagittal.
• Prefixes for Position and Direction:
  • circum-: around, example: circumoral; around the mouth
  • peri-: around, example: periorbital; around the orbit
  • intra-: in, within, example: intravascular; within a vessel
  • epi-: on, over, example: epithelial; referring to epithelium, tissue that covers surfaces
  • extra-: outside, example: extrathoracic; outside the thorax
  • sub-: below, under, example: sublingual; under the tongue
  • inter-: between, example: intercostal; between the ribs
  • juxta-: near, beside, example: juxtaposition; a location near or beside another structure
  • para-: near, beside, example: parasagittal; near or beside a sagittal plane
  • retro-: behind, backward, example: retrouterine; behind the uterus
  • supra-: above, example: suprapatellar; above the patella

Body Cavities

• Internal organs are located within dorsal and ventral cavities
• The nine abdominal regions include right hypochondriac, epigastric, left hypochondriac region
• Also the right lumbar, the umbilical region plus the left lumbar region
• The right iliac, the hypogastric region and left iliac region

Word Parts Pertaining to Body Structure

• Cephal/o means head, for example Megacephaly
• Cervic/o means neck, for example cervicofacial
• Thorac/o means chest/thorax, example thoracotomy
• Abdomin/o means abodomen, example intra-abdominal
• Lapar/o means abdominal wall, example laparoscope
• Lumb/o means lumbar region, lower back, example thoracolumbar
• Periton/o means peritoneum, example peritoneal
• Acro- means extremity, end, for example Acrocyanosis
• Brachi/o means arm, for example Brachial artery
• Dactyl/o means finger, toe, for example Polydactyly
• Ped/o means foot, for example Pedometer
• Pod/o means foot, for example podiatric