An introduction to the human body

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Anatomy

the structure or study of the strucutre of the body and the relation of its parts to each other

Physiology

science that deals with the functions of an organism or its parts

Embryology

the study of the first eight weeks of development following the fertilization of an egg in humans

Developmental biology

the study of the complete development of an individual from fertilization of an egg to death

Cell biology

the study of cellular structure and functions

Histology

the study of microscopic structure of tissues

Surface anatomy

the study of surface markings of the body to understand internal anatomy through visualization and palpation (gentle touch)

Gross anatomy

the study of structures taht can be examined withough using a microscope

Regional anatomy

teh study of specific regions of teh body such as teh head or chest

Radiographic anatomy

the study of body structures that can be visualized with x-rays

Pathological anatomy

the study of structural (from gross to microscopic) associated with disease

Neurophysiology

the study of functional properties of nerve cells

Endocrinology

the study of hormones (chemical regulators in the blood) and how they control body functions

Cardiovascular physiology

the study of functions of the heart and blood vessels

Immunology

the study of how the body defends itself against disease-causing agents

Respiratory physiology

the study of functions of the air passageways and lungs

Renal physiology

the study of the functions of the kidneys

Exercise physiology

the study of changes in cell and organ functions as a result of muscular activity

Pathophysiology

the study of functional changes associated with disease and aging

Levels of structural organization in the human body

chemical, organelle, cellular, tissue, organ, system, and organismal

Chemical level

includes atoms, and molecules; carbon, hydrogen, oxygen, nitrogen, phosphorus, calcium, and sulfur are essential for maintaining life

Cellular level

molecules combine to form cells (contains organelles), the basic structural and functional units of an organism; (ex of cells, muscle, nerve, and epithelial)

Tissue level

tissues are group of cells and the materials surrounding them that work together to perform a particular function; there are 4 basic types of tissue in the human body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue

Organ level

different types of tissues are joined together; organs are stuctures taht are composed of two or more different types of tissues; they have specific functions and usually have recognizable shapes (e.g., the stomach, skin, bones, heart, liver, lungs, and brain)

System level

a system consists of related organs with a common function; an example of a system is the digestive system, which breaks down and absorb food; its organs include teh mouth, salivary glands, pharynx (throat), esophagus, stomach, small intestine, large intestine, liver, gallbladder, and pancreast

Organismal level

an organism is a living individual; all the parts of the human body functioning together constitue the total organism

Organelle level

molecules aggregate to form organelles, which are subcellular structures

Eleven systems of the human body

integumentary, skeletal, muscular, nervous, endocrine, digestive, cardiovascular, urinary, lymphatic and immunity, reproductive, and respiratory

Integumentary system

components: skin and structures associated with it, such as hair, nails, sweat glands, and oil glands; functions: protects teh body; helps regulate body temperature; eliminates some wastes; helps make vitamin D; and detects sensations such as touch, pain, warmth, and cold

Skeletal system

components: bones and joints of the body and their associated cartilages; functions: supports and protects the body; provides a surface area for muscle attachments; aids body movements; houses cells taht produce blood cells; stores minerals and lipids (fats)

Muscular system

components: muscles composed of skeletal muscle tissue, so -named because it is usually attached to bones; functions: produces body movements, such as walking; stabilizes body position (posture); generates heat

Nervous system

components: brain, spinal cord, nerves, and special sense organs, such as the eyes and ears; functions: generates action potentials (nerve impulses) to regulate body activities; detects changes in the body's internal and external environments, interprets the changes, and responds by causing muscular contractions or glandular secretions

Endocrine system

components: hormone-producing glands (pineal gland, hypothalamus, pituitary gland, thymus, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries, and testes) and hormone-producing cells in several other organs; function: regulates body activities by releasing hormones, which are chemical messengers transported in blood from an endrocrine gland or tissue to a target organ

Cardiovascular system

components: blood, heart, and blood vessels; functions: heart pumps blood through blood vessels; blood carries oxygen and nutirents to cells and carbon dioxide and wastes away from cells and helps regulate acid-base balance, temperature, and water content of body fluids; blood components help defend against disease and repair damaged blood vessels

Digestive system

components: organs of gastrointestinal tract, a long tube that includes teh mouth, pharynx (throat), esophagus, stomach, small and large intestines, and anus; also includes accessory organs that assist in digestive processes, such as salivary glands, liver, gallblader, and pancreas; functions: achieves physical and chemical breakdown of food; absorbs nutrients; eliminates solid wastes

Urinary system

components: kidneys, ureters, urinary bladder, and urethra; functions: produces, stores, and eliminates urine; eliminates wastes and regulates volume and chmical composition of blood; helps maintain the acid-base balance of body fluids; maintains body's mineral balance; helps regulate production of red blood cells

Lymphatic system and immunity

components: lymphatic fluid (lymph) and vessels; also includes spleen, thymus, lymph nodes, and tonsils; functions: returns proteins and fluid to blood; carries lipids from gastrointestinal tract to blood; includes structures where lymphocytes that protect against disease-causing microbes mature and proliferate

Respiratory system

components: lungs and air passageways such as the pharynx (throat), larynx (voice box), trachea (windpipe), and bronchial tubes leading into and out of the lungs; functions: transfers oxygen from inhaled air to blood and carbon dioxide from blood to exhaled air; helps regulate acid-base balance of body fluids; aire flowing out of lungs through vocal cords produces sounds

Reproductive systems

components: gonads (testes in males and ovaries in females) and associated organs (uterine tubes, uterus, and vagina in femals and epididymis, ductus deferens, and penis in males); functions: gonads produce gametes (sperm or oocytes) that unite to form a new organism; gonads also release hormones that regulate reproduction and other body processes; associated organs transport and store gametes

Characteristics of life

metabolism, responsiveness, movement, growth, differentiation, reproduction, evolution

Metabolism

the sum of all the chemical processes that occur in the body; including catabolism (the breakdown of complex chemical substances into simpler components) and anabolism (the building up of complex chemical substances from smaller, simpler components

Responsiveness

the body's ability to detect and respond to changes; for example, a decrease in body temperature represents a change in teh internal environment (within the body), and turning your head toward the sound of squealing brakes is a response to change in teh external environment (outside the body); different cells in teh body respond to environmental changes in characteristic ways; nerve cells respond by generating electrical signals known as nerve impulses (action potentials); muscle cells respond by contracting, which generates force to move body parts

Movement

includes motion of the whole body, individual organs, single cells, and even tiny structures inside cells

Growth

an increase in body size that results from an increase in teh size of existing cells, an increase in teh number of cells, or both; in addition, a tissue sometimes increases in size because the amount of material between cells increase

Differentiation

teh development of a cell from an unspecialized to a specialized state; for example, red blood cells and several types of white blood cells all arise from teh same unspecialized precuror cells in red bone marrow

Reproduction

refers eitehr to the formation of new cells for tissue growth, repair, or replacement, or to the production of a new individual

Homeostasis

the condition of equilibrium in teh body's internal environment due to the constant interaction of the body's many regulatory processes

Body fluids by the numbers

make up 55% to 60% of human body (42 liters); 2/3 of fluid is intracellular fluid; 1/3 of fluid is extracellular fluid [80% is insterstitial, 20% (2L) is blood plasma]

Extracellular fluid

composed of insterstitial fluid, blood plasma, and transcellular fluid

Instertitial fluid

the extracellular fluid that fills the narrow spaces between cells of tissues

Transcellular fluid

makes up <1% of extracellular fluid; encompasses lymph (ECF within lymphatic vessels), cerebrospinal fluid (ECF in and around the brain), synovial fluid (ECF in joints), aqueous humor (ECF of teh eyes), vitreous body (ECF of the eyes)

Feedback system

a cycle of events in which the status of a body condition is monitored, evaluated, changed, remonitored, reevaluated, and so on; includes a receptor, a control center, and an effector

Receptor

a body structure that monitors changes in a controlled condition and sends input to a control center; typically the input is in the form of nerve impulses or chemical signals

Control center

sets the range of values within which a controlled condition should be maintained, evaluates teh input it receives from receptors, and generates output commands when they are needed; output from the control center typically occurs as nerve impulses, or hormones, or other chemical agents

Effector

a body structure that receives output from the control center and produces a response or effect that changes the controlled situation

Operation of a feedback system

some stimulus disrupts homeostasis by increasing or decreasing a controlled condition that is monitored by receptors; receptors send input (nerve impulses or chemical signals) to the control center, which receives the input and provides the output (nerve impulses or chemical signals) to effectors, the output brings about change in the effector or creates a response that alters the controlled condition; there is a return to homeostasis when the response brings the controlled condition back to normal

Negative feedback system

most common form; reverses a change in a controlled condition; returns the value to normal range

Homeostatic regulation of blood pressure by a negative feedback system

some stimulus disrupts homeostasis by increasing blood pressure; baroreceptors (receptors) in certain blood vessels send nerve impulses (input); the brain (control center) interprets input and sends nerve impulses (output) to the heart and blood vessels (effectors), which lead to a decrease in heart rate, which then leads a decrease in blood pressure; the condition returns to homeostasis when response brings blood pressure back to normal

Positive feedback system

tends to strenghten or reinforce a change in one of the body's controlled conditions

Positive feedback control of labor contraction during birth of a baby

contraction of wall of uterus force baby's head or body into the cervix, thus increasing the stretching of cervix; stretch-sensitive nerve cells in cervix (receptors) send nerve impulses (input); the brain (control center) interprets the input and releases oxytocin (output); muscles in the wall of the uterus contract more forcefully; the baby's body stretches the cervix more; increased stretching of cervix causes release of more oxytocin which results in more stretching of the cervix; the birth of the baby decreases the stretching of the cervix, thus breaking the cycle

Epidemiology

the science that deals with why, when, and where diseases occur and how they are transmitted among individuals in a community

Anatomical position

the subject stands erect facing the observer, with the head level and the eyes facing directly forward; the feet are flat on the floor and directed forward, and the upper limbs are at the sides with the palms turned forward; the body is upright

Insulin

removes excess glucose from the blood

Glucagon

stimulates the release of stored glucose

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