Notes for Chapter 1 Slides
Form and Function of Anatomy & Physiology
Anatomy – study of the structure of body parts and their relationships to one another.
Physiology – study of the function of body parts; how they work to carry out life-sustaining activities.
Anatomy and physiology are inseparable – function always reflects structure; what a structure can do depends on its specific form.
Principle of complementarity of structure and function: function follows form.
Structural Organization
The human body is highly organized, from the smallest chemical level to the whole organism level.
Levels include atoms, molecules, cells, tissues, organs, organ systems, and the organism.
Necessary Life Functions
Maintenance of life involves several essential activities:
Maintaining boundaries: separation between internal and external environments must exist.
Movement: muscular system allows movement of body parts and substances.
Responsiveness (irritability): ability to sense and respond to stimuli.
Digestion: breakdown of ingested food and absorption of nutrients.
Metabolism: all chemical reactions that occur in the body; includes anabolism and catabolism.
Excretion: removal of wastes produced by metabolism and digestion.
Reproduction: cell division for growth or repair; production of offspring.
Growth: increase in size of body parts.
Organ Systems
Humans are multicellular; organ systems service the cells.
There are 11 organ systems that cooperate to maintain life:
Integumentary System
Skeletal System
Muscular System
Nervous System
Endocrine System
Cardiovascular System
Lymphatic/Immune System
Respiratory System
Digestive System
Urinary System
Reproductive System (Male and Female)
System-by-System Overview
(a) Integumentary System
Forms the external body covering; protects deeper tissues from injury.
Synthesizes vitamin D; houses cutaneous receptors (pain, pressure, etc.) and sweat/oil glands.
(b) Skeletal System
Protects and supports body organs; provides framework for muscles to cause movement.
Blood cells form within bones; bones store minerals.
(c) Muscular System
Allows manipulation of the environment, locomotion, and facial expression.
Maintains posture and produces heat.
(d) Nervous System
Fast-acting control system; responds to internal/external changes by activating muscles and glands.
(e) Endocrine System
Glands secrete hormones that regulate growth, reproduction, and metabolism in body cells.
(f) Cardiovascular System
Blood vessels transport blood carrying oxygen, carbon dioxide, nutrients, wastes, etc.; heart pumps blood.
(g) Lymphatic System / Immunity
Returns leaked fluids to blood; disposes of debris; houses lymphocytes involved in immunity.
Immune response mounts attacks against foreign substances.
(h) Respiratory System
Keeps blood supplied with oxygen and removes carbon dioxide; gas exchange occurs in alveoli.
(i) Digestive System
Breaks down food into absorbable units entering the blood for distribution to cells; eliminate indigestible wastes as feces.
(j) Urinary System
Eliminates nitrogenous wastes; regulates water, electrolyte, and acid-base balance of the blood.
(k) Male Reproductive System
Overall function: production of offspring. Testes produce sperm and male hormones; ducts/glands aid in delivering sperm.
(l) Female Reproductive System
Overall function: production of offspring. Ovaries produce eggs and female hormones; remaining structures serve as sites for fertilization and fetal development; mammary glands produce milk.
Homeostasis
Homeostasis is the maintenance of relatively stable internal conditions despite continuous changes in the environment.
It is a dynamic state of equilibrium, always readjusting as needed.
The nervous and endocrine systems, along with other systems, regulate homeostasis.
Variables are factors that can change (e.g., blood sugar, body temperature, blood volume).
Homeostatic Control Components
Three components: receptor, control center, effector.
Receptor (sensor): monitors environment; responds to stimuli that cause changes in a controlled variable.
Control center: determines set point; receives receptor input; decides on an appropriate response.
Effector: receives output from control center; provides means to respond; action reduces (negative feedback) or enhances (positive feedback) the stimulus.
Homeostatic Controls
Negative feedback – Most common in the body; response reduces or shuts off the original stimulus.
Variable changes in the opposite direction of the initial change.
Examples: regulation of body temperature; regulation of blood glucose by insulin and glucagon.
Positive feedback – Response reinforces or exaggerates the original stimulus.
Typically controls infrequent, short-lived events; not a continuous adjustment.
Examples: platelet plug formation and blood clotting; enhancement of labor contractions by oxytocin.
Negative Feedback Mechanism (Example: Body Temperature)
Control Center (thermoregulatory center in brain).
Receptors: temperature-sensitive cells in skin and brain.
Effectors: sweat glands, skeletal muscles.
Process:
Stimulus: heat -> sweat production increases -> body temperature falls -> stimulus ends.
Stimulus: cold -> shivering begins -> body temperature rises -> stimulus ends.
Balance vs. imbalance is achieved through this loop.
Negative Feedback to Control Blood Sugar
Blood glucose rises: pancreatic glucagon is released; liver breaks down glycogen and releases glucose.
Pancreas also releases insulin to promote glucose uptake by cells and conversion of glucose to glycogen in the liver.
Result: blood glucose level falls.
Positive Feedback (Detailed Example)
Example: Labor contractions during childbirth.
Sequence leads to increased contraction, leading to more oxytocin release, etc., until birth; feedback cycle breaks when cervix stretching ceases.
Anatomical Position and Directional Terms
Standard anatomical position: body erect; feet slightly apart; palms facing forward; thumbs pointing away from body.
This position serves as a reference point for describing anatomical terms.
Orientation and Directional Terms (Table 1.1)
Superior (cranial) vs Inferior (caudal)
Superior: toward the head end or upper part of a structure; e.g., the head is superior to the abdomen.
Inferior: away from the head end toward the lower part; e.g., the navel is inferior to the chin.
Anterior (ventral) vs Posterior (dorsal)
Anterior: toward or at the front of the body; e.g., the breastbone is anterior to the spine.
Posterior: toward the back of the body; e.g., the heart is posterior to the breastbone.
Note: In humans, ventral and anterior are synonymous; in four-legged animals, anterior refers to the leading/ventral surface.
Medial vs Lateral
Medial: toward or at the midline of the body.
Lateral: away from the midline; toward the outer side.
Intermediate
Between a more medial and a more lateral structure.
Proximal vs Distal
Proximal: closer to the origin of a body part or limb attachment to the trunk.
Distal: farther from the origin of a part or attachment of a limb to the trunk.
Superficial vs Deep
Superficial: toward or at the body surface.
Deep: away from the body surface; more internal.
Regional Terms
Axial region: head, neck, trunk.
Appendicular region: limbs (arms and legs).
Regional terms designate specific areas within body divisions.
Cephalic, Facial, and cervical terms; thoracic, abdominal, pelvic; as well as upper and lower limbs with subregions (acromial, brachial, antecubital, antebrachial, carpal, manus, palmar, pollex, digital; etc.).
Examples:
Upper limb: acromial, brachial, antecubital, antebrachial, carpal, manus; palmar, pollex, digital.
Lower limb: femoral, patellar, crural, fibular (peroneal), tarsal, metatarsal, digital, calcaneal, plantar, etc.
Back/vertebral column areas: scapular, vertebral, lumbar, sacral, gluteal, perineal, etc.
Note on terminology: cephalic (head), otic (ear), occipital (back of head), etc.; dorsal/posterior versus ventral/anterior terminology distinctions.
Body Planes and Sections
Body planes are surfaces along which the body or structures may be cut for study:
Sagittal plane: divides body vertically into right and left parts.
Midsagittal (median) plane: along the midline.
Parasagittal plane: off-center.
Frontal (coronal) plane: divides body vertically into anterior and posterior parts.
Transverse (horizontal) plane: divides body horizontally into superior and inferior parts.
Oblique section: cuts at an angle other than 90° to the vertical plane.
Body Cavities and Membranes
The body contains internal cavities that are closed to the environment and protect organs.
Two major sets of cavities:
Dorsal body cavity
Ventral body cavity
Dorsal Body Cavity
Cranial cavity: encases brain.
Vertebral (spinal) cavity: encases spinal cord.
Ventral Body Cavity
Houses internal organs (viscera) and is divided by the diaphragm into compartments:
Thoracic cavity
Pleural cavities: each surrounds one lung.
Mediastinum: contains pericardial cavity; encloses heart; surrounds other thoracic organs.
Abdominopelvic cavity
Abdominal cavity
Pelvic cavity
Abdominopelvic Quadrants and Regions
Abdominopelvic region is divided into four quadrants (quadrants not listed here but implied): RUQ, etc.
Abdominopelvic Regions (nine regions):
Right hypochondriac, Epigastric, Left hypochondriac
Right lumbar, Umbilical, Left lumbar
Right iliac (inguinal), Hypogastric, Left iliac (inguinal)
Abdominopelvic Organs (illustrative example from region image)
Anterior view shows several superficial organs in the nine regions, including:
Liver, Gallbladder, Ascending colon of large intestine, Small intestine, Cecum, Appendix
Diaphragm, Spleen, Stomach, Transverse colon of large intestine
Descending colon of large intestine, Initial part of sigmoid colon, Urinary bladder
Other Body Cavities
Cavities exposed to the environment:
Oral cavity (and digestive cavities)
Nasal cavity
Orbital cavities
Middle ear cavities
Cavities not exposed to the environment:
Synovial cavities (joint cavities)