Body Systems

11.1: Animal bodies are organized into a structural hierarchy

  • Form and Function

    • Provide insight into correlation between both

  • Anatomy Versus Physiology

    • Anatomy

      • study of the structure of an organism’s body parts (its form)

    • Physiology

      • study of the functions of those parts

    • two disciplines complement each other in helping us to better understand how the body works.

  • A Structural Hierarchy

    • individual cells are organized into larger and larger working units

    • At each level of organization, new functions emerge that were not present in the structures at lower levels

    • Cells - tissues - organs - systems —> organism

Core Idea: Form (anatomical structures) and function (physiological actions) relate to each other. Your body consists of a structural hierarchy running from cells to tissues to organs to organ systems to the whole organism.

Q: Your brain is an example of what level of the structural hierarchy?

A: An organ.

11.2: The human body contains several major types of tissues

  • Tissue

    • integrated group of similar cells that performs a specific function

  • Connective Tissue

    • consists of cells scattered throughout an extracellular matrix

    • provides support

    • Depending on type of connective tissue, matrix consists of protein fibers embedded in a liquid, jelly, or solid

  • Epithelium

    • Most body and organ surfaces are covered with epithelial tissue, also called epithelium

      • Consists of sheets of tightly packed cells that are fused together

    • epithelial cells release secretions, such as oil on your skin and mucus in your respiratory tract

  • Nervous Tissue

    • Nervous tissue communicates signals between different parts of the body.

    • Within your brain, spinal cord, and nerves, individual cells called neurons can transmit rapid electrical signals along spindly extensions. Such signals allow you to sense the world, formulate a response, and act on it.

  • Muscle Tissue

    • Muscle Tissue abundant in most animals - makes up “meat” of body

    • Muscle fibers contains specialized proteins that allow it to contract (shorten)

Core Idea: Most animal bodies contain a number of tissues. Each tissue consists of similar cells that work together to perform a specific function. Organs are in turn made up of two or more types of tissue.

Q: Poke your forearm with your finger. What types of tissue can you feel?

A: You can probably feel epithelium (in your epidermis), adipose (fat), skeletal muscle, and bone.

11.3: An animal’s internal environment remains relatively constant

  • Homeostasis

    • Animal bodies tend to maintain relatively constant internal conditions even when external enviro changes

    • Tendency called homeostasis, word meaning “steady state”

  • Diabetes: A Breakdown in Homeostasis

    • Body of a person with diabetes mellitus either fails to produce insulin (as in type 1, or insulin-dependent diabetes) or target cells don’t respond normally to insulin that is produced (as in type 2)

    • Without regulation by insulin, cells of individual with diabetes cannot obtain enough glucose from blood, even though thereis plenty

    • Type 1 patients require strict monitoring

    • Type 2 diabetes usually associated with obesity and can be controlled through diet + exercise, and medication

  • The Integumentary System and its Role in Temperature Homeostasis

    • Every system in body plays a role in homeostasis

    • Circulatory system carries hormones that help regulate glucose lelvels

    • Integumentary System, organ system that interacts most directly with the environment, organs such as skin, hair and nails that protect the body against physical harm

  • Homeostasis in Action: Temperature Regulation

    • Negative feedback - a form of regulation in which the result of a process inhibits the process of body detecting and responding to changes in environment

Core Idea: All animal bodies exchange chemicals and energy with the environment, but tend to maintain nearly constant internal conditions. Homeostasis, such as maintaining blood glucose levels and internal temperature, is often maintained by negative feedback.

Q: Flushing a toilet causes water to rush into the tank, which lifts a float until it turns off the water. Explain how this demonstrates negative feedback.

A: This is an example of negative feedback because the result of the process (water entering the tank) turns off that process.

11.4: The human digestive system consists of an alimentary canal and accessory organs

Digestive System: Consists of a long tube (called the alimentary canal) and a series of organs that secrete digestive chemicals into it. Breaks down food into smaller and smaller bits until all that remains are molecules tiny enough to pass into your body cells

  • Alimentary Canal

    • A long tube that is divided along its length into specialized digestive organs. At each stop along the alimentary canal, specific steps in the processing of food occur.

  • Accessory Organs

    • Secretes specific digestive chemicals into alimentary canal via ducts

  • Nutrient Absorption in the Small Intestine

    • Structure correlates with function of nutrient absorption

    • Epithelial tissue lining inside of small intestine folded into finger-like extensions (villi)

      • Each cell along villi has microscopic projections called microvilli

        • Structure gives small intestine huge surface area where absorption can occur

  • Peristalsis

    • Waves of contractions in the muscle that line the alimentary canal

    • Food squeezed into stomach, doesn’t fall in

Core Idea: The human digestive system consists of an alimentary canal (divided into organs along its length) and various accessory organs, including salivary glands and organs that release digestive juices into the small intestine.

Q: If the most important function of the digestive system is the absorption of nutrients, which one organ is primarily responsible?

A: The small intestine.

11.5: Food is processed in a series of stages

- Process of converting food to forms that body can use is divided into four stages

  • The Processing of Food

    • (1) Ingestion

      • First stage

      • All animals ingest other organisms, whole or by the piece

    • (2) Digestion

      • Breakdown of food into molecules small enough to be absorbed by the body

      • Mechanical digestion

        • Use of physical processes to break down food into smaller pieces

      • Chemical digestion

        • Use of enzymes to perform hydrolysis

    • (3) Absorption

      • Only after extensive digestion are food molecules small enough for cells to absorb

      • Uptake of these small nutrient molecules, primarily by the cells that line extensive folds of the small intestine

      • Nutrients enter blood vessels surrounding the small intestine

        • Transported to all cells of body

    • (4) Elimination

      • Disposal of undigested matter from body

      • Food waste accumulates as feces in rectum and later exits digestive tract via anus

(INSERT DIAGRAM INTO STUDY GUIDE)

11.6: Proper nutrition provides energy and building materials

  • Eating Right

    • MyPlate - reminds us of how to make healthy food choices!

    • Eat mostly whole grains, avoid sodium, drink water, high-fat foods on occasion, limit empty calories, be physically active

  • A table shows U S D A recommended daily amounts of the five food groups.

  • Essential Nutrients

    • Materials body can’t make itself

    • Absence causes disease

    • 4 classes

      • Minerals

        • Inorganic chemical elements required to maintain health.

      • Vitamins

        • Organic (carbon-containing) nutrient required in diet

      • Essential Fatty Acids

        • Fatty acids that can’t be produced by the body

      • Essential Amino Acids

        • Amino acids that must be obtained from diet because human cells can’t make them

11.7: An unbalanced diet or malfunctioning digestive system can lead to health problems

- Two broad categories of ailments are associated with the digestive system: those caused by a malfunctioning or diseased digestive organ, and those caused by improper diet.

  • What Can Go Wrong

    • Many illnesses are caused by infection or malfunction of the organs of the digestive system.

      • Acid Reflux

        • Caused by backflow of partially digested food into the esophagus.

      • Gallstones

        • Solid crystals of bile, can obstruct the gallbladder or its ducts

      • Constipation

        • Mvmt of feces through colon slows, too much water reabsorbed and feces become compacted

      • Appendicitis

        • Infection of the appendix by bacteria and indicated by sharp pains on right side of abdomen. Most ppl cured by surgery.

      • Cholera

        • Improper sanitation can lead to infection of small intestine. Bacterium releases toxin that produces diarrhea, so severe that it can quickly lead to dehydration, and if untreated, death.

      • Inflammatory Bowel Disease

        • Several intestinal disorders - including Crohn’s disease are caused by painful inflammation of intestinal wall

      • Ulcer

        • Harming of lining of the stomach.

  • Gastric Bypass

    • Most common weight loss surgery

      • Stomach is reduced in size to a small pouch

      • Portion of small intestine downstream attached, bypassing large portion of stomach

  • Nutritional Imbalances

    • An improper diet can have severe health consequences. A number of different nutritional disorders can arise, each with different causes

      • Obesity

        • Nutritional Imbalance of greatest concern.

        • Defined as high body mass index (BMI), ratio of weight to height

  • Malnutrition

    • Caused by diet that lacks sufficient calories or essential nutrients.

    • Most common is protein deficiency

    • Swollen bellies due to fluid accumulation in the abdomen

  • Eating Disorders

    • Malnutrition not always caused by lack of access to food

    • Anorexia nervosa

      • Caused by self-starvation due to fear of gaining weight, even when person is underweight

    • Bulimia

      • Pattern of binge eating followed by purging through induced vomiting, misuse of laxatives, or excessive exercise.

    • Culture, genetics, psychology, and brain chemistry tend to play a role but not exactly sure

11.8: The respiratory system exchanges gases between the environment and the body

- Humans can last a week without food, several days without water.

- If you don’t breathe for 10 minutes, you’ll die.

- Immediate survival thus depends on properly functioning respiratory system (several organs that facilitate exchange of oxygen (O2) and CO2 btwn body and enviro)

- Many structures contribute, but the actual exchange of gases occurs between blood capillaries and alveoli (tiny air sacs) in your lungs.

  • The Human Respiratory System

    • Breathing (alternation of inhalation (in) and exhalation (out) exposes lungs to air)

    • Airways highly branched, ending in a huge number of sacs, big surface area for O2 to diffuse into bloodstream and CO2 to diffuse out

      • Pharynx

        • Opening at back of throat, junction of respiratory and digestive systems

        • Food lodged in pharynx or trachea can cause choking unless freed via Heimlich maneuver

      • Trachea

        • Windpipe, conveys air from pharynx into lungs

      • Bronchioles

        • Bronchi branch into smaller and smaller tubes

      • Alveoli

        • Small sacs at end of each bronchiole, actual site of gas exchange

      • Diaphragm

        • Sheet of muscle that separates chest cavity from the abdomen. Movement controls inhalation and exhalation. Blow to diaphragm can shock muscle, preventing you from taking a breath

      • Nasal cavity

        • Air enters respiratory system through nostrils and mouth

        • As air is inhaled, it is filtered, passed over smell receptors, warmed, and moistened

      • Epiglottis

        • Entry of air into windpipe regulated by epiglottis

        • Movable flap covers trachea, preventing food from entering

      • Larynx

        • Contains a pair of vocal chords. During exhalation, air moves through the larynx and vibrates vocal chords producing sounds

  • Gas Exchange

    • Primary function of respiratory system to exchange gasses

    • Circulatory system transports oxygen from lungs to all body cells, and transports CO2 from body cells back to lungs

11.9: The circulatory system transports materials throughout the body

- Cells rely on circulatory system — a collection of organs and tissues that acts as an internal transport network. Circulating blood passes near every body cell, allowing materials to diffuse in and out

  • The Human Circulatory System

    • Cardiovascular system consists of heart (cardio) and blood vessels (vascular)

    • Heart pumps blood thru a series of branching tubes (arteries, arterioles, capillaries, venules, veins)

    • Blood carries nutrients and wastes between different bodily location

  • Double Circulation

    • Human cardiovascular system organized into 2 circuits:

      • Pulmonary circuit

      • Systemic circuit

  • Blood Vessels

    • 3 types of blood vessels make up “plumbing” of circulatory system

      • Arteries (and smaller arterioles) carry blood from heart

      • Veins (and smaller venules) carry blood to the heart

      • Capillaries join arterioles to venules, providing site for exchange of materials between blood and body’s cells

What Can Go Wrong

  • Hypertension (High blood pressure)

    • Persistent blood pressure higher than 140 and/or diastolic blood pressure higher than 90

  • Anemia

    • Occurs when there is abnormally low amt of hemoglobin (oxygen-carrying molecule within red blood cells) or a low number of red blood cells

The human cardiovascular system, including the heart and the blood vessels branching throughout the body: the arteries, arterioles, capillaries, venules and veins.

Double circulation has been illustrated.

Blood flows from the heart through arteries which branch into arterioles, and then through a network of capillaries; then through venules branching to veins as blood flows back to the heart

11.10: The heart is the hub of the human circulatory system

- Heart, fist-sized muscular organ located under sternum (breastbone), is central hub of human circulatory system.

  • Cardiac Anatomy

    • The human heart contains four chambers that control the movement of blood: one atrium and one ventricle on each side.

    • The atria collect blood returning to the heart through veins and squeeze it a short distance into the ventricles

      • Pump blood out

Path of blood through the heart is: from the body, to the right atrium, the right ventricle, the lungs, the left atrium, the left ventricle, then to the body.

  • Cardiac Cycle

    • Rhythmic contraction and relaxation of heart muscles

    • Natural electrical pace maker within heart coordinates steps in each cardiac cycle

      • Interferes with nervous system, allowing cycle to be sped up or slowed down in response to signals from the brain

The cardiac cycle consists of diastole and systole; regulated by the sinoatrial node, which is the heart’s pacemaker, and the atrioventricular node which ensures the ventricles contract strongly.

  • Coronary Arteries

    • When blood exits the heart via the aorta, several coronary arteries immediately branch off, running along outside of heart, and supply the heart muscle itself with oxygenated blood

    • If one or more of the coronary arteries become blocked, heart muscle cells quickly die from lack of oxygen

      • Myocardial infaraction (heart attack)

    • Treatment: Angioplasty (tiny balloon used to widen clogged arteries), stents (wire mesh tubes propping open clogged arteries), or bypass surgery (section of blood vessel from leg used to shunt around clog)

    • Healthy arteries: Healthy diet, losing weight, exercising, avoiding smoking, and (if needed) taking cholesterol-lowering medication

11.11:

  • Blood

    • fluid of the human circulatory system

    • Consists of many small molecules and several types of cells dissolved in plasma (liquid)

      • Yellowish liquid of blood in which blood cells are suspended

    • provides long-distance transportation for O2, CO2, nutrients, wastes, etc throughout body

  • Blood Types

    • based on carbs that may or may not be found on surface of red blood cells

    • Genes code for blood type - some genes code for production of carbohydrate called A, B, or none at all

    • Types: A,B,AB, O

  • Clotting

    • Platelets - bits of cells pinched off from larger cells in the bone marrow and begin healing process

      • A piece of cytoplasm from large cell in bone marrow, a blood clotting element

    • Makes sure we don’t bleed to death when cut

11.12: The immune system contains a huge number of defensive elements

- Environment teems w/ pathogens, disease-causing microorganisms

- Immune system - body’s system of protection against infectious diseases

  • External Defenses

    • First line of defense against infections — a set of barriers that prevent pathogens from penetrating deep inside body

    • Defenses always ready to act

External defenses include hairs and cilia, mucous membranes, stomach acid, skin, and sweat, saliva and tears.

  • The Inflammatory Response

    • If one is cut and doesn’t properly treat injury, site will probably become red, swollen, painful

      • Signs of inflammatory response

Diagram of the inflammatory response.

  • The Lymphatic System

    • When body fights an infection, lymphatic system kicks into high gear

      • Branching network of fluid-filled vessels and numerous small organs called lymph nodes

      • Produces lots of blood cells when needed

      • Invading microbes picked up by fluid (lymph), swept into lymph nodes, then attacked by lymphocytes (white blood cells)

Diagram of the lymphatic system.

  • Specific Immunity

    • If external defenses fail and infection occurs, specific immunity comes into play.

    • Components of specific immunity must first be primed by exposure to an antigen, a molecule that elicits an immune response.

      • Molecules on the surfaces of microorganisms such as the flu virus.

    • Depends on lymphocytes, white blood cells that reside in the lymphatic system. Lymphocytes come in two varieties: B cells and T cells.

  • Antibodies

    • Every white blood cell has, on its surface, many copies of a specific protein receptor that is capable of binding to one kind of antigen

    • The immune system contains a tremendous variety of lymphocytes, enough to bind to just about every possible antigen.

      • Once an antigen is bound, B cells secrete antibodies, proteins that circulate in the blood that are specific for that same antigen.

Antibodies are produced by the specific immune system.

  • Clonal Section

    • Particular antigen will activate only a few white blood cells happening to have matching receptors

    • Once activated, they multiply, producing large population of lymphocytes (white blood cells) all specific for the same invading antigen

      • Clonal selection — allows immune system to maintain a vast army of cells, but produces reinforcements only when they are needed.

Clonal selection occurs during the specific immune response.

  • Destroying ZE Invaders

    • Once antigens recognized, must be destroyed

    • Antibodies bind antigen, most likely neutralizing threat

    • If not, antibodies marshal several types of cells and molecules that work to destroy the invader.

    • One type of lymphocyte, helper T cells, can recognize antigens and then stimulate the production of several types of immune cells.

Invaders are destroyed as part of the specific immune system.

  • Memory

    • First time lymphocytes encounter a particular antigen, clonal selection produces memory cells that can live for decades

    • If the same invader is encountered again, the memory cells will instigate a vigorous and rapid immune response that neutralizes the invader before it causes illness

Memory forms a part of the specific immune system.