Chapter 1: Orientation to the Human Body

Anatomy

Studies the “structure'“ of body parts and their relationships to one another, includes three subparts

Physiology

Focuses on the “function” of body systems and how they work together (encompasses processes such as metabolism, homeostasis and regulation)

How do anatomy and physiology relate to each other?

They are complementary since function depends on structure. Anatomy provides the physical design and framework, while physiology explains how that design works to keep the body alive.

Gross (macroscopic) Anatomy

The study of large physical structures visible to the naked eye. Has three subdivisions; regional, structural, systemic

Regional Anatomy

Study of body’s specific structures by focusing on specific parts/areas ex. head, chest, limbs

Systemic Anatomy

Study of specific organ systems ex. nervous system, cardiovascular system

Surface Anatomy

Study of external body features/landmarks that can be seen or felt through the skin ex. clavicle (collarbone), patella (kneecap)

Microscopic Anatomy

Study of fine, detailed structures that are not visible to the naked eye; biological cells, tissues, organs using a microscope (two subdivisions: histology and cystology)

Histology

Study of tissues

Cytology

Study of the structure, function and chemistry of individual cells (a way to diagnose/screen for diseases with a small amount of tissue or body fluids)

Developmental Anatomy

Study of structural changes an organism undergoes from fertilization to adulthood

Topics of Physiology

Organ Systems, Cellular & Molecular Events (cells interacting to create tissues), Basic Physical Principles (electricity, pressure), Basic Chemical Principles (chemical bonds, biochemistry)

Which approach to gross anatomy is used in an A&P course?

Regional approach, studying all structures in a specific body area together

Levels of Organization (that makeup the body)

atoms → molecules → organelles → cells → tissues → organs → organ systems → organism

Explain the relationships between the levels of organization

Atoms combine to form molecules → cells are made up of molecules → tissues consist of similar types of cells → organs are made up of different types of tissues → organ systems consist of different organs that work together closely → the human organism is made up of organ systems

Integumentary System (main functions & components)

Forms the external covering, protects deeper tissues from injury, synthesizes vitamin D, houses receptors (pain, pressure) and sweat and oil glands

Main components: skin, hair, nails

Skeletal System

Protects and supports body organs, provides a framework the muscles use to cause movement; blood cells are formed within bones, bones store minerals (calcium)

Muscular

Allows manipulation of the environment, locomotion (the ability of an organism to move itself from one place to another) and facial expression; maintains posture and produces heat

Nervous System

Fast-acting control system of the body, it responds to internal and external changes by activating appropriate muscles and glands

Homeostasis

A dynamic steady state that regulates the body and maintains equilibrium

Significance: keeps the body’s internal environment stable & safe, required for survival

Positive Feedback

Occurs when the initial response enhances the original stimulus so that further responses are even greater or amplified (the change that results proceeds in the same direction as the initial change)

Negative Feedback

A control system that counteracts a change in the body to bring conditions back to a stable point

Steps in the Homeostatic Control System (5 steps)

1.Stimulus produces change in variable 2.receptor detects change 3.input: information sent along afferent pathway to control center (afferent “approaches”) 4.output: information sent along efferent pathway to effector (efferent info “exits”) 5.response of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level

Effectors for body temperature regulation

Sweat glands: secrete sweat on the skin surface

Skeletal muscles: contract rapidly during shivering to generate heat

Receptors for body temperature regulation

Thermoreceptors (specialized sensory neurons)

Location of Control Center for Homeostasis

Hypothalamus: monitors and regulates core body temperature, blood pressure, thirst, hunger, sleep cycles and hormone levels

Examples of Positive Feedback

Childbirth: Stronger contractions push the baby harder against the cervix during childbirth, repeating the cycle until delivery

Blood clotting: damaged blood vessels release signals that recruit platelets, which release more signals to bring in even more platelets until the leak stops

3 Components of all Homeostatic Systems

Receptor: a sensor that monitors the environment and detects change (known as stimuli)

Control center: the component that analyzes the input received from the receptor, compares it to the normal set point and determines the right response

Effector: an organ, gland or muscle that receives output from the control center and acts to bring about the change needed to restore balance

Anatomical Position

Body is erect, feet slightly apart, palms facing forward, thumbs pointed away from the body

Directional Terms (definition & significance)

Allows us to explain where one body structure is in relation to another; creates a universal standard that prevents confusion when describing body structures and locations

Axial

Regional term, makes up the main “axis” of our body: head, neck, trunk

Appendicular

Regional term, consists of the “appendages” or limbs (arms, legs) which are attached to the body’s axis

3 Body Planes

Sagittal, coronal, transverse

Sattigal (body plane)

Left to Right

Coronal (body plane)

Front (anterior) & Back (posterior)

Transverse (body plane)

Up (superior) & Down (inferior)

Dorsal Body Cavity (2 subdivisions)

Function: protects the fragile nervous system

Cranial cavity: contains brain

Spinal cavity: contains spinal cord

Ventral Body Cavity (2/3 subdivisions)

Thoracic cavity: contains heart and lungs

Abdominal-pelvic cavity: abdominal contains stomach, intestines, spleen, liver and other digestive organs; pelvic cavity contains urinary bladder, reproductive organs and rectum)

Superior (cranial)

Toward the head/upper part of the body or a structure (ex. the head is ___ to the abdomen)

Inferior (caudal)

Away from the head or toward the lower part of the body or a structure (ex.the heel is ___ to the thigh)

Anterior (ventral)

Toward the front of the body (ex. the breastbone is ____ to the spine)

Posterior (dorsal)

Toward the back of the body (ex. the heart is ____ to the breastbone)

Medial

Toward or at the midline of the body (ex. the heart is ___ to the arm)

Lateral

Away from the midline of the body (ex. the arms are ___ to the heart)

Intermediate

Between a more medial and more lateral structure (ex. the collarbone is ___ between the breastbone and shoulder)

Proximal

Closer to the center of attachment/ the body, trunk, or point of attachment (ex. the shoulder is ___ to the elbow)

Distal

Farther from the origin of a body part (ex. the knee is ___ to the thigh)

Superficial (external)

Toward or at the body surface (ex. the skin is ___ to the skeletal muscles)

Deep (internal)

Away from the body surface, more internal (ex. the lungs are ___ to the skin)

Organs in RUQ

Liver, gallbladder, right kidney, head of pancreas

Organs in LUQ

Largest part of the stomach, spleen, body and tail of pancreas, left kidney, adrenal gland

Organs in RLQ

Appendix, right ovary and fallopian tube, right ureter

Organs in LLQ

Descending colon, left ovary and fallopian tube, left ureter