Chapter 1: The Human Body: An Orientation

What is x-ray imaging used for?

• detecting broken bones

• finding breast tumors

• screening for osteoporosis

What are the light areas in x-ray imaging?

dense structures

What are the dark areas in x-ray imaging?

hollow air-containing organs

What are the drawbacks of x-ray imaging?

• radiation exposure

• 2D images

What is a Computed Tomography (CT) scan?

a computerized reconstruction of a series of x-ray images that provide detailed cross-sectional pictures of scanned body regions

What is a Computed Tomography (CT) scan used for?

images of bone, soft tissues, and blood vessels

What is the drawback of a Computed Tomography (CT) scan?

more radiation exposure than x rays

What is Digital Subtraction Angiography?

digitally subtracting images from before and after injection of an x-ray-absorbing contrast agent that yields very clear images of blood vessels

What is Digital Subtraction Angiography used for?

detecting blood vessel abnormalities such as blockages in the arteries that supply the heart

What are the drawbacks of Digital Subtraction Angiography?

• time-consuming and expensive

• adverse reactions to the contrast medium can occur

How do Positron Emission Tomography (PET) scans work?

they use gamma rays that are emitted by radioactively tagged tracer molecules that are injected into the body

What are Positron Emission Tomography (PET) scans used for?

• detecting the spread of cancer

• monitoring the response to cancer treatment

• may help diagnose Alzheimer’s

What are the drawbacks of Positron Emission Tomography (PET) scans?

• radiation exposure

• relatively poor image resolution

How does Magnetic Resonance Imaging (MRI) work?

it uses powerful magnets and radio waves to image the location of hydrogen atoms in the body, distinguishing body tissues based on water content and producing high-contrast images of soft tissues

What does a functional MRI (fMRI) do?

tracks blood flow into various parts of brain

What is Magnetic Resonance Imaging (MRI) used for?

• imaging of brain, spinal cord and nerves detect abnormalities

• fMRI allows visualization of the activity in specific brain regions

What are the drawbacks of Magnetic Resonance Imaging (MRI)?

• more expensive and much slower than CT scans

• cannot be used in patients with most types of metal implants

How does ultrasound imaging work?

it uses high-frequency sound waves that reflect off of the body’s tissues

What is ultrasound imaging used for?

• monitoring a fetus during pregnancy

• diagnosing abdominal or pelvic disorders

• detecting atherosclerosis and heart valve disorders

What is the drawback of ultrasound imaging?

images tend to be lower resolution

x-ray imaging

CT scan

digital subtraction angiography

PET scan

MRI

ultrasound imaging

What is anatomy?

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

What is physiology?

the function of the body; how the body parts work and carry out their life-sustaining activities

What is the major difference between anatomy and physiology?

anatomy is concrete and tangible while physiology is explainable only in terms of the underlying anatomy

What is the weight of a healthy young reference male?

155 lb (70 kg)

What is the weight of a healthy young reference female?

125 lb (57 kg)

Why do we rarely see extreme anatomical variations from person to person?

because they are incompatible with human life

What is sex?

a set of biological attributes

What is sex ultimately based on?

chromosomes, gene expression, and the actions of hormones

What is sex generally reflected in?

an individual’s reproductive anatomy and physiology

What is gender?

a psychosocial construct consisting of behaviors, expressions and identities

What is gross anatomy?

the study of large body structures visible to the naked eye (e.g. heart, lungs, kidneys)

What Greek word does the term “anatomy” come from?

anatomia, meaning to cut apart

What are the subdivisions of gross anatomy?

regional, systemic and surface anatomy

What is regional anatomy?

when all the structures in a particular region of the body (e.g. abdomen or leg) are examined at once

What is systemic anatomy?

when body structure is studied system by system

What is surface anatomy?

the study of internal structures as they relate to the overlying skin surface

What is microscopic anatomy?

the study of structures too small to be seen with the naked eye

How is microscopic anatomy usually carried out?

exceedingly thin slices of body tissues are stained and mounted on glass slides to be examined under the microscope

What are the subdivisions of microscopic anatomy?

cytology and histology

What is cytology?

the study of the cells of the body

What is histology?

the study of tissues

What is developmental anatomy?

the study of structural changes that occur throughout the life span

What is a subdivision of developmental anatomy?

embryology

What is embryology?

the study of the developmental changes that occur before birth

What is palpation?

feeling organs with your hands

What is auscultation?

listening to organ sounds with a stethoscope

What are some subdivisions of physiology?

renal physiology, neural physiology, and cardiovascular physiology

What is renal physiology?

the study of kidney function and urine production

What is neurophysiology?

the study of the workings of the nervous system

What is cardiovascular physiology?

the study of the operation of the heart and blood vessels

Why does physiology often focus on events at the cellular or molecular level?

because the body’s abilities depend on those of its individual cells, and a cell’s abilities ultimately depend on the chemical reactions that go on within it

Why does physiology rest on principles of physics?

to explain electrical currents, blood pressure, and the way muscles use bones to cause body movements

What is the principle of complementarity of structure and function?

the function of a certain body structure depends on its specific form

What is an example of the principle of complementarity of structure and function?

the urinary bladder can store urine because it stretches and expands as urine accumulates

What is the simplest level of the structural hierarchy?

the chemical level

What takes place at the chemical level?

atoms combine to form molecules

What is the order of structural organization from simple to complex?

chemical, cellular, tissue, organ, organ system, organism

What are cells?

the smallest units of living things

What are tissues?

groups of similar cells that have common function

What are the four basic tissue types?

epithelial, muscle, connective, and nervous

What does muscle tissue do?

provides movement

What does connective tissues do?

supports and protects body organs

What does nervous tissue do?

provide a means of rapid internal communication by transmitting electrical impulses

What is an organ?

a discrete structure composed of at least two tissue types that perform a specific function of the body

What become possible at the organ level?

extremely complex functions

What is an organ system?

a group of organs that work together to accomplish a common purpose (e.g. cardiovascular system – heart and blood vessels)

What is the highest level of organization?

the organism

What does the organismal level represent?

the sum total of all structural levels working together to keep us alive

Why are all body cells interdependent?

because humans are multicellular organisms and our vital body functions are parceled out among different organ systems

What are the functions of the integumentary system?

• forms the external body covering

• protects deeper tissues from injury

• houses cutaneous receptors and sweat and oil glands

What are the functions of the skeletal system?

• protects and supports body organs

• provides a framework the muscles use to cause movement

• serves as location where blood cells are formed

• stores minerals

What are the functions of the muscular system?

• allows manipulation of the environment, locomotion and facial expression

• maintains posture

• produces heat

What are the functions of the nervous system?

• serves as the fast-acting control system of the body

• responds to internal and external changes by activating appropriate muscles and glands

What is the function of the endocrine system?

secretes hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells

What are the functions of the cardiovascular system?

• transports blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc., via blood vessels

• pumps blood via the heart

What are the functions of the lymphatic system?

• picks up fluid leaked from blood vessels and returns it to blood

• disposes of debris in the lymphatic stream/houses white blood cells (lymphocytes) involved in immunity

• its immune response mounts the attack against foreign substances within the body

What are the functions of the respiratory system?

keeps blood constantly supplied with oxygen and removes carbon dioxide

What are the functions of the digestive system?

• breaks down food into absorbable units that enter the blood for distribution to body cells

• eliminates indigestible foodstuffs as feces

What are the functions of the urinary system?

• eliminates nitrogenous wastes from the body

• regulates water, electrolyte, and acid-base balance of the blood

What are is the function of the reproductive system?

producing offspring

What are the specific functions of the male reproductive system?

• testes produce sperm and male sex hormone

• male ducts and glands aid in delivery of sperm to the female reproductive tract

What are the specific functions of the female reproductive system?

• ovaries produce eggs and female sex hormones

• the remaining female structures serve as sites for fertilization and development of the fetus

• mammary glands produce milk for the newborn

How does the plasma membrane serve as a boundary?

it separates the intracellular fluid inside cells from the extracellular fluid outside

How does the integumentary system (skin) serve as a boundary?

it protects our internal organs from drying out, infection, and the damaging effects of heat, sunlight, and chemicals in the external environment

How does the skeletal system aid movement?

by providing the bony framework that the muscles pull on as they work

What is contractility?

the muscle cell’s ability to move by shortening

What is responsiveness (a.k.a. excitability)?

the ability to sense changes (stimuli) in the environment and then respond to them

Why is the nervous system most involved with responsiveness?

because nerve cells are highly excitable and communicate rapidly with each other via electrical impulses

What is digestion?

the breaking down of ingested foodstuffs to simple molecules that can be absorbed into the blood

What is metabolism?

the broad term for all chemical reactions that occur within body cells

What is catabolism?

breaking down substances into simpler building blocks

What is anabolism?

synthesizing more complex substances from simpler building blocks

What is cellular respiration?

using nutrients and oxygen to produce ATP

What does metabolism depend on the digestive and respiratory systems to do?

make nutrients and oxygen available to the blood