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UNIT 13: BODY SYSTEMS
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UNIT 13:BODY SYSTEMS
An Overview of Anatomy and Physiology
Anatomy is the study of the structure and shape of the body and body parts and their relationship to one another.
Physiology is the study of how the body and its parts work or function.
Structure determines what functions can take place.
Levels of Structural Organization
• The human body exhibits many levels of structural complexity.
• The simplest level of the structural ladder is the chemical level. At this level, atoms, tiny building blocks of matter, combine to form molecules.
• Molecules associate in specific ways to form microscopic cells.
• Cells, the smallest units of all living things, are made up of atoms, elements, compounds, and molecules.
• Individual cells vary widely in size and shape, reflecting their particular functions in the body.
The Atom
Living and nonliving things are made up of tiny units called atoms.
The nucleus is the center core of an atom.
The Atom The nucleus is made up
of particles called protons and neutrons.
Protons have a positive charge (+1) and neutrons
have no electrical charge (0).
Electrons are negatively charged particles (-1)
that revolve around the nucleus at different distances from the nucleus.
Multicellular Organisms
A multicellular organism is a group of cells that live and work together in one organism.
There is differentiation and cell specialization.
Differentiation means cells or tissues change from relatively generalized to specialized kinds.
Cell Specialization means a cell becomes specialized for just one function.
Advantage of having cell specialization: A cell that only has to do one function can be much more efficient at that one job.
Disadvantage of cell specialization: The cells are dependent upon one another. If one group of cells fails to do its job, the other cells will perish.
Multicellular Organisms
LEVELS OF CELL ORGANIZATION:
Cell: the smallest unit of a living organism Tissue: a group of similar cells all
performing a similar activity Organ: several tissues functioning as a unit Organ systems: systems that form a
multicellular organism Organism: all the various systems that
form a multicellular organism
structural organization from cell to tissue to organ to organ system
(smallest to largest)
Organ System Overview▪ The integumentary system is the external covering
of the body, or skin.
▪ The skeletal system consists of bones, cartilages, ligaments, and joints.
▪ The muscular system are formed by the skeletal muscles.
▪ Tendons are part of the muscular system and connect muscles to bones.
▪ Ligaments are also part of the muscular system and connect bone to bone.
Integumentary System
Skeletal System
Organ System Overview The nervous system is the body’s fast-
acting control center that consists of the brain, spinal cord, nerves, and sensory receptors.
The endocrine system controls body activities by producing chemical molecules called hormones, and releasing them into the blood to travel to relatively distant target organs.
The cardiovascular system includes the heart and blood vessels.
Nervous System
The Human Brain The human brain weighs only about three pounds and
has three main parts:
1. The cerebrum fills up most of your skull. It is involved in remembering, problem solving, thinking, and feeling. It also controls movement.
2. The cerebellum sits at the back of your head, under the cerebrum. It controls coordination and balance.
3. The brain stem sits beneath your cerebrum in front of your cerebellum. It connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate and blood pressure.
The cerebrum, or cerebral cortex, is the largest part of the human brain. The cerebrum is associated with higher brain function such as thought, memory, consciousness, action, and intelligence. The cerebral cortex is divided into four sections, called "lobes“ and includes the frontal lobe, parietal lobe, occipital lobe, and temporal lobe.
Frontal Lobe - associated with reasoning, planning, parts of speech, movement, emotions, and problem solving
Parietal Lobe - associated with movement, orientation, recognition, perception of stimuli
Occipital Lobe - associated with visual processing
Temporal Lobe - associated with perception and recognition of auditory stimuli, memory, and speech
The cerebellum, or "little brain," is similar to the cerebrum in that it has two hemispheres and has a highly folded surface or cortex.
The cerebellum is associated with regulation and coordination of movement, posture, and balance.
The brain stem lies between the spinal cord and the rest of the brain. The brain stem is responsible for basic vital life functions such as breathing, heartbeat, blood pressure, movement of the eyes and mouth, relaying sensory messages (hot, pain, loud, etc.), hunger, consciousness, body temperature, involuntary muscle movements, sneezing, coughing, vomiting, and swallowing.
The brain stem is made of the midbrain, pons, and medulla.
Cardiovascular System
pituitary gland: small gland located at the base of the brain that secretes nine hormones to regulate homeostasis, one of which is a growth hormone
pineal gland: small gland in the vertebrae brain that produces the serotonin derivative melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions
thyroid gland: large gland is found in the neck and functions to control how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones.
thymus gland: a specialized organ of the immune system that "educates" T-lymphocytes (T cells), which are critical cells of the immune system
adrenal gland: sit atop the kidneys and chiefly function to release hormones in response to stress, particularly cortisol (increases blood sugar) and adrenaline (fight or flight response)
pancreas: a gland organ in the digestive system that functions in the endocrine system by producing several hormones including insulin, glucagon, somatostatin, and pancreatic polypeptide, and as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist the absorption of nutrients and the digestion in the small intestine
Glucagon raises blood glucose levels.
Insulin lowers blood glucose levels.
Organ Systems Overview The lymphatic system is complementary to
that of the cardiovascular system, and includes lymphatic vessels, lymph nodes, and other lymphoid organs.
The respiratory system keeps the body supplied with oxygen and removes carbon dioxide, and consists of the nasal passages, pharynx, larynx, trachea, bronchi, and lungs.
The digestive system breaks down food and delivers the products to the blood for dispersal to the body cells.
Lymphatic System
Respiratory System
Digestive System
The lymphatic system is the complementary system to that of the cardiovascular system, and includes lymphatic vessels, lymph nodes, and other lymphoid organs. The function of the lymphatic system is to remove excess fluid and some pathogens from the body.
major organs of the lymphatic system and
their locations
Organ System Overview
The urinary system removes the nitrogen-containing wastes such as urea and uric acid from the blood and flushes them from the body in urine.
The reproductive system exists primarily to produce offspring.
The Urinary System
Maintaining Life: Necessary Life Functions Every living organism must be able to
maintain the boundaries so that its “inside” remains distinct from its “outside.”
Movement includes all the activities promoted by the muscular system that propels the body from one place to another.
Responsiveness, or irritability, is the ability to sense changes (stimuli) in the environment and then to react to them.
Digestion is the process of breaking down ingested food into simple molecules that can then be absorbed into the blood for delivery to all body cells by the cardiovascular system.
Metabolism refers to all chemical reactions that occur within body cells.
Excretion is the process of removing excreta, or wastes, from the body.
Reproduction, the production of offspring, can occur on the cellular or organismal level.
Growth is an increase in size, usually accomplished by an increase in the number of cells.
Survival Needs The goal of nearly all body systems is to
maintain life.
To maintain life, and organism requires certain factors called survival needs:
1.) Nutrients 2.) Oxygen 3.) Water 4.) Body temperature must be maintained. 5.) Appropriate atmospheric pressure must
be maintained on the surface of the body.
Homeostasis Homeostasis is a type of biological balance.
Cells and organisms MUST maintain relatively stable internal conditions even though the outside world is continuously changing.
This includes maintaining:
- water levels- temperature- sugar, salt, and chemical
compositions
Homeostatic Control Mechanisms
Communication within the body is essential for homeostasis and is accomplished chiefly by the nervous and endocrine systems, which use electrical signals delivered by nerves or bloodborne hormones, respectively, as information carriers.
All homeostatic control mechanisms have at least three components:
a receptor a control center an effector
A receptor is a type of sensor that monitors and responds to changes in the environment. Information flows from the receptor to the control center along the afferent pathway.
The control center determines the level (set point) at which a variable is to be maintained, analyzes the information it receives and then determines the appropriate response or course of action.
The effector provides the means for the control center’s response (output) to the stimuli. Information flows from the control center to the effector along the efferent pathway.
Feedback Mechanisms In a negative feedback loop, the net effect of the
response to the stimulus is to shut off the original stimulus or reduce its intensity.
This is similar to a home heating system connected to a thermostat.
An example of a negative feedback loop would be the hypothalamus helping to regulate body temperature.
Another example of a negative feedback loop would be the regulation of blood glucose levels or pH levels within the body.
an example of a negative feedback mechanism
Feedback Mechanisms A positive feedback loop tends to increase the
original disturbance (stimulus) and to push the variable farther from its original value.
Examples of positive feed back mechanisms are much more rare in the body, such as blood clotting and the birth of a baby.
During blood clotting, the positive feedback loop is initiated when injured tissue releases signal chemicals that activate platelets in the blood.
An activated platelet releases chemicals to activate more platelets, causing a rapid cascade and the formation of a blood clot.
Feedback Mechanisms Another example of a positive feedback loop
occurs during childbirth.
During childbirth, when a contraction occurs, the hormone oxytocin is released into the body, which stimulates further contractions. This results in contractions increasing in amplitude and frequency to hasten childbirth.
Most homeostatic control mechanisms are negative feedback mechanisms.
Homeostatic Imbalance
Homeostatic imbalance results when internal body conditions become less efficient and less stable.
This can be caused by aging, which can lead to disease and a greater risk of illness.
Homeostatic imbalance in the body is brought about by abnormal conditions of the body’s physiological mechanisms.
That’s all, Folks!
NOTE: No animals were injured or
disfigured during the making of this
animation.
