Human Organ Systems

• Organ systems are groups of organs working together to perform major bodily activities.

Skeletal System

• Made of bones, cartilage, and joints
• Forms the body's framework
• Protects internal organs
• Stores minerals
• Provides attachment points for muscles

Muscular System

• Composed of:
  • Smooth
  • Cardiac
  • Skeletal muscle tissue
• Skeletal muscle:
  • Attached to the skeleton via tendons
  • Responsible for body part movement
• Smooth muscle (visceral muscle):
  • Found in internal organs
  • Lines blood vessel walls
  • Makes up the iris
  • Forms the gut wall
• Cardiac muscle forms the bulk of the heart, controlling blood circulation.

Circulatory System

• Consists of:
  • Blood
  • Blood vessels
  • Heart
• Transports oxygen, carbon dioxide, nutrients, wastes, hormones, vitamins, minerals, and water throughout the body
• Aids in temperature regulation

Digestive System

• Converts food to simple substances the body can use.
• Composed of:
  • Mouth
  • Pharynx
  • Esophagus
  • Stomach
  • Small and large intestines
• Aided by accessory organs:
  • Liver
  • Gall bladder
  • Pancreas

Excretory System

• Made up of:
  • Skin
  • Lungs
  • Sweat glands
  • Kidneys
• Removes metabolic wastes from the body
• Kidneys eliminate the bulk of wastes

Reproductive System

• Generates reproductive cells (gametes)
• Provides a mechanism for fertilization
• Maintains the developing embryo until it can survive outside the body
• Ovaries are female primary reproductive organs
• Testes are male primary reproductive organs

Nervous System

• Regulates and coordinates the body’s responses to internal and external environmental changes.
• Major structures include:
  • Brain
  • Spinal cord
  • Nerves.

Endocrine System

• Consists of:
  • Hypothalamus
  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenal glands
  • Pancreas
  • Ovaries
  • Testes
• Helps maintain homeostasis, regulates temperature, and controls growth, development, metabolism, and reproduction by secretion and releasing hormones

Integumentary System

• First line of defense, protecting the body
• Composed of:
  • Skin
  • Hair
  • Nails
  • Sweat and oil glands
• Protects against injury, infection, and fluid loss
• Aids in temperature regulation

Human Skeletal System Functions

• Forming a sturdy internal framework of 206 bones
• Providing a base for muscle attachment and leverage for movement
• Protecting vital organs like the brain, spinal cord, heart, and lungs
• Storing vitamins and minerals, especially calcium and phosphorus
• Housing red bone marrow, which produces blood cells
• Bone is connective tissue made of osteocytes in a calcified matrix
• Compact bone has a periosteum and surrounds spongy bone; cavities contain red/yellow marrow
• Movement occurs at joints
• Slightly movable joints act as cushions
• Freely movable (synovial) joints allow range of motion
• Ligaments are inelastic connective tissues that hold bones together at joints

Diagram of Human Skeleton

• Provides support
• Axial skeleton (skull, ribs, sternum, vertebral column) is rigid
• Appendicular skeleton (arms, legs, shoulders, hips) is movable
• Articulation of bones forms joints for flexibility

Diagram of Human Bone

• Two-thirds of bone is calcium and phosphorus salts, providing rigidity
• Collagen makes up the nonliving bone matrix
• Osteoblasts produce new bone by secreting collagen
• Osteocytes are trapped osteoblasts
• Osteoclasts reorganize bone
• Osteoporosis is severe bone loss
• Compact bone structures as concentric rings (lamellae) around a haversian canal
• The circular Haversian system allows bone to withstand stress

Human Muscular System Functions

• Primarily produces movement
• Generates heat
• Maintains body positions and postures
• Muscles controlled by stimuli from the nervous system
• Sarcomere is muscle tissue's functional unit
• Muscle contracts shortening the sarcomere from actin sliding over myosin
• Muscles work in antagonistic pairs, since they can only pull, not push
• Flexors decrease joint angles
• Extensors increase joint angles
• Skeletal muscle:
  • Attached to skeleton with tendons
  • Controlled consciously
  • Long, fiber-like, multinucleated cells
• Lack of use causes muscle atrophy
• Smooth muscle:
  • Found in internal organs
  • Movement is usually involuntary
  • Spindle-shaped cells with one nucleus
• Cardiac muscle:
  • Involuntary
  • Found only in the heart
  • Contain gap junctions for ion diffusion and electrical impulse spread
• There are more than 600 voluntary muscles in the body, with skeletal muscles being the strongest
• Skeletal muscles account for ~23% of a woman’s weight and ~40% of a man’s

Three Types of Human Muscle Tissue

• Skeletal muscle: long, striated, multinucleated cells under voluntary control that attach to the skeleton
• Smooth muscle: spindle-shaped cells with a single nucleus, surrounding hollow internal structures, and are involuntary controlled
• Cardiac muscle: striated and involuntary, found only in the heart

Skeletal Muscle Contraction

• Muscles contains bundles of muscle fibers made of actin/myosin protein
• The myosin filament attaches to actin to form a "crossbridge"
• ATP powers the crossbridge, pulling the actin filament to the sarcomere's center

Human Circulatory System

• Transports nutrients, gases, wastes, water, and hormones
• Distributes heat
• Composed of:
  • Heart
  • Vessels
  • Blood
  • Lymphatic system
• Consists of the heart, blood vessels, and blood
• Blood vessels include arteries, veins, and capillaries
• Heart rate is usually 60-70 beats/min from the sinoatrial node

Blood Components

• Plasma:
  • Liquid matrix
  • 90% water, 10% solutes
  • Maintains osmotic pressure
• Cellular portion:
  • Red blood cells (erythrocytes) transport oxygen
  • White blood cells (leukocytes) defend against infection
  • Platelets aid in blood-clotting reactions
• Erythrocytes (RBCs):
  • Lack a nucleus as mature cells
  • Contain hemoglobin to bind and transport oxygen
• Leukocytes (WBCs):
  • Have nuclei and are larger than RBCs
  • Neutrophils, eosinophils, and basophils are granular
  • Monocytes and lymphocytes are non-granular
• Platelets:
  • Cytoplasm pieces
  • Pinched off megakaryocyte cells
• Lymphatic system is a series of vessels and nodes, filtering out bacteria/microorganisms

Diagram of the Human Heart

• The atria are receiving chambers
• The ventricles are pumping chambers
• Blood collects from the body into the right atrium
• Right atrium blood goes through the tricuspid valve, then the right ventricle
• The right ventricle contracts, forcing blood via the pulmonary valve into the pulmonary arteries and the lungs.
• Blood returns to the left atrium via pulmonary veins
• Blood flows past the mitral valve into the left ventricle
• Left ventricle blood exists through the aortic valve to the body(systemic circulation
• Heart rhythm originates in the sinoatrial node (pacemaker)
• Autonomic nervous system affects heart rate, but cannot initiate it
• Pulse, blood pressure and electrocardiograms can be used for tracking heart/blood vessel health

Human Immune System

• Composed of cells and tissues which defend the body against pathogens
• Initial responses are nonspecific
• Skin and mucous membranes are the body’s first defense line
• Inflammatory response initiates histamine and prostaglandin release upon pathogen entry to increase blood circulation to the infection site
• Increased body temperature prevents pathogens from reproduction
• Interferon prevents viral synthesis of proteins/RNA in surrounding cells
• Nonspecific defense is mounted by neutrophils, macrophages and natural killer cells which attack and destroy pathogenic organisms
• Specific immune responses are triggered when pathogens survive nonspecific defenses
• Specific defenses include humoral/cell-mediated immunity
• Antigens trigger the immune response
• Humoral immunity protects against pathogens in blood/lymph through B cells
• Cell-mediated immunity involves killer T cells which cause pathogenic cells to rupture and die

Disease Control

• Robert Koch connected specific bacteria to diseases and established criteria for identifying pathogenic bacteria; guidelines used for medical microbiology today
• Edward Jenner’s experiments led to the modern vaccination
• A vaccine contains dead/modified pathogens injected to create immunity
• Smallpox eradicated through vaccination in 1977
• Allergic responses occur when antigens attach to mast cells
• Mast cells release histamines, increasing blood flow and fluid secretion, resulting in an allergic reaction
• Autoimmune disorders are when the body attacks own cells
• Acquired Immune Deficiency Syndrome (AIDS) compromises the immune system

Human Respiratory System

• O2 is vital for metabolism
• Gas exchange between body cells, blood, and air in lungs is called respiration that is cellular
• Cellular Respiration is when energy from food molecules is released
• O2 is transported by hemoglobi while binding to red blood Cells
• CO2 also transported by diffusing into plasma, binding to hemoglobin and forming bicarbonate compound in blood
• Human respiratory system consists of the nose, pharynx, larynx, trachea, bronchi, and lungs, which are framed by the rib cage and diaphragm
• Breathing produced by pleural cavity size differences, creating a partial vacuum
• Diaphragm contracts and rib cage raises, increasing pleural cavity volume
• Average breathing rate in humans is ~14 breaths per minute
• Lung diseases such as Bronchitis, pneumonia, emphysema, asthma and lung cancer can occur from bacteria
• Lung disease can be inflicted by either smoking, breathing of containing air or bacteria

Diagram of Human Respiratory System

• Air (mostly nitrogen, ≈21% oxygen) enters nose, filtered by hairs
• Tissues moisturize and warm air
• Air travels from the pharynx, larynx (with vocal cords), trachea, left/right bronchi, bronchioles, and alveoli
• Airways have mucous membranes and cilia
• Bronchioles open into alveoli
• Alveoli are one-cell thick and contact capillaries for gas exchange
• The Alveoli creates an enormous surface area for sufficient O2/CO2 for the whole body

Human Digestive System

• Digestion breaks down nutrients for cellular use
• Digestion involves:
  • Mechanical digestion
  • Chemical digestion
  • Absorption
• Process begins in mouth, with chewing and saliva secretion
• Swallowing reflex initiates peristalsis to transport food to stomach
• Stomach contains muscle layer to aid mechanically mixing food, and turns into chyme
• Chemical digestion begins through hydrochloric acid and pepsin
• Small intestine absorbs nutrients and digestion
• Villi and microvilli in small intestine increase the surface area for absorption and secretion
• Large intestine absorbs water and vitamin K, synthesized by bacteria
• Undigested or unabsorbed food is then eliminated
• Nutrients must be broken down (carbohydrates -> monosaccharides, proteins -> amino acids, lipids -> fatty acids and glycerin)
• Vitamins are organic molecules
• Water allows metabolism/chemical reactions and transport

Diagram of Human Digestive System

• Digestive system includes the mouth, pharynx, esophagus, stomach, small and large intestines, as well as accessory organs
• Nutrients are used for metabolism, building, and repair; some are stored within the body
• The lining of the small intestine contains villi, which have brush border enzymes and contain capillaries and lymphatic vessels

Human Excretory System

• Excretion removes metabolic wastes such as carbon dioxide, salts, water, and chemicals
• Excretory organs consist of the skin, lungs and kidneys
• CO2 generated from cellular respiration is removed from the lungs
• The skin excretes water, salts & sweat
• The kidneys excrete most of the metabolic waste and have about one million nephrons

Human Urinary System

• Consists of kidneys, ureters, urinary bladder, urethra
• Eliminates most metabolic wastes from the body
• Functional unit is nephron
• Nephron consists of the Bowman’s capsule, tubules, and capillaries
• Blood pressure increases within the glomerulus, causing blood fluid to enter Bowman’s capsule
• Filtrate passes tubule portion, reabsorbing materials the body needs and filters out waste
• Kidneys ensure proper homeostasis

Human Reproductive System

• Produces gametes (eggs and sperm)
• Facilitates fertilization producing a zygote
• Testes produce sperm (male gamete) in the seminiferous tubules
• Sperm travels through epididymus and vas deferens, past the seminal vesicle, through prostate, and out through the urethra.
• Testosterone is primary male androgen, regulated through biofeedback
• Ovaries produce eggs before birth

Diagram of Human Male Reproductive System

• Semen is ejaculated during sexual intercourse
• Testes produce sperm in seminiferous tubules
• Sperm is transported into the epididymis which improves sperm fertility
• Sperm moves through the vas deferens to the urethra, where seminal vesicle and prostate gland adds nutrients, creating semen

Diagram of Human Female Reproductive System

• Ovaries contain eggs
• Eggs are released monthly and swept into the fallopian tube by cilia, for fertilization.
• Vagina deposits semen during sexual intercourse
• A fertilized egg implants in the endometrium of the uterus

Human Endocrine System

• Ductless glands produce hormones that are released into the bloodstream
• Glands include the hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, adrenal, pancreas, ovary
• Exocrine glands secrete through a duct or tube to specific locations
• Hormones are chemical messengers that bind which affect other cell activities
• Hormones are controlled through negative feedback system
• Steroid hormones are produced from lipid, cholesterol
• Nonsteriod hormones are made from amino acids

Human Endocrine System Diagram

• the Hypothalamus, Pituitary gland, Thymus, Thyroid and Parathyroid glands, Adrenal gland, Pancreas, Testis, and the Ovary are all major regulatory system components of the human body