HomeostasisCh. 19
The Human Body – An Orientation
• Anatomy – study of the structure and shape of the body and its parts
• Physiology – study of how the body and its parts work or function
Levels of Structural Organization
Anatomy – Levels of Study
• Gross Anatomy
– Large structures
– Easily observable
• Microscopic Anatomy
– Very small structures
– Can only be viewed with a microscope
Survival Needs
• Nutrients
– Chemicals for energy and cell building
– Carbs, proteins, lipids, vit. & minerals
• Oxygen - required for chemical reactions
• Water
– Provides for metabolic reaction
– Stabilizing body temperature
Homeostasis
• Internal Equilibrium (or balance)
• Maintenance of a stable internal environment = a dynamic state of equilibrium
• Homeostasis must be maintained for normal body functioning and to sustain life
• Homeostatic imbalance – a disturbance in homeostasis resulting in disease
Maintaining Homeostasis
• The body communicates through neural and hormonal control systems
– Receptor are stimulated to:
• Responds to the changes in the environment (stimuli)
• Sends information to control center
This is achieved mostly by the nervous system & the endocrine system
Maintaining Homeostasis
– The Control center:
• Analyzes information that is received from the receptors (affector)
• Determines the appropriate response
– Effector
• Provides a means for response to the stimulus (sends a reaction message to the effector)
Feedback Mechanisms
• Homeostasis is maintained in the body through Negative feedback
– It works in response to a change that counteracts another change.
– Its output response that affects the initial input feedback decreases its effect
– Works like a household thermostat: it can shut off the original stimulus, or reduces its intensity
– Includes most homeostatic control mechanisms
Feedback Mechanisms
• Positive feedback:
– Is the opposite of negative feedback
– It intensifies the original change by increasing the original stimulus to push the variable farther, rather than reversing itself to return to a set point.
– In the body this only occurs in blood clotting and birth of a baby
Homeostasis (Positive Feedback)
Body Tissues
• Cells are specialized for particular functions
• Tissues
– Groups of cells with similar structure and function
– Four primary types
• Epithelium
• Connective tissue
• Nervous tissue
• Muscle
Cell Diversity
Cell Diversity
Cell Diversity
Cell Diversity
Epithelial Tissues
• Layers of tissue
– Simple – one layer
– Stratified – more than one layer
• Found in different areas
– Body coverings
– Body linings
– Glandular tissue
• Functions
– Protection
– Absorption
– Filtration
– Secretion
Classification of Epithelium
• Shape of cells
– Squamous – flattened
– Cuboidal – cube-shaped
– Columnar – column-like
Glandular Epithelial Tissues
• Cells that produce and release substance
• Exocrine glands
– Have ducts
– Sweat glands, oil glands, salivary glands
• Endocrine glands
– Ductless
– Produce hormones
– Excrete hormone into the extracellular fluid & diffuse into nearby capillaries.
– Pancrease: glucogon & insulin
Connective Tissue Characteristics
• Supports and binds other tissues
• Variations in blood supply
– Some types are well vascularized and other types have poor blood supply
• Cartilage: flexible & resilient
– Consists of spaced cells and extracellular matrix – a non-living material that surrounds living cells
Cartilage tissue
Connective Tissue Types
• Bone (osseous tissue) is composed of:
• Bone cells in lacunae (cavities)
• Hard matrix of calcium phsophate
Adipose Tissue
• Insulates the body
• Protects some organs
• Serves as a site of fuel storage
Connective tissue: Blood
• 3 types of connective tissues in blood:
– RBC
– WBC
– Platelets
• Blood cells surrounded by fluid matrix called: Plasma
Muscle Tissue
• Function is to produce movement
• Three types: Skeletal, Cardiac, Smooth muscle
Nervous Tissue
• Neurons and nerve support cells
• Function is to send impulses to other areas of the body
– Irritability
– Conductivity
Regeneration of Tissues
• Tissues that regenerate easily
– Epithelial tissue
– Fibrous connective tissue and bone
• Tissues that regenerate poorly
– Skeletal muscle
• Tissues that are replaced largely with scar tissue
– Cardiac muscle
– Nervous tissue within the brain and spinal cord
The Skin
Organ System Overview
• Circulatory System
(Cardiovascular)
– Transports materials in bodyvia blood pumped by heart
• Carbon dioxide
• Nutrients
• Wastes
– Includes heart, blood vessels & blood
Organ System Overview
• Lymphatic System
– Returns fluids to blood vessels
– Disposes of debris
– Involved in immunity
• Includes lymph, lymph nodes & vessels, WBC
Organ System Overview
• Digestive System
– Breaks down food
– Allows for nutrient absorption into blood
– Eliminates indigestible material
Includes: mouth, esophagus, stomach, sm. & lg. Intestines, anal, rectum
Organ System Overview
• Excretory/ Urinary System
– Eliminates nitrogenous wastes
– Maintains acid – base balance
– Regulates water and electrolytes
Includes: kidneys, ureters, bladder, urethra
Organ System Overview
• Respiratory System
– Keeps blood supplied with oxygen
– Removes carbon dioxide
• Includes: nose, trachea, & lungs; (gills in fish & some amphibians)
Organ System Overview
• Endocrine System
– Secretes regulatory hormones for:
• Growth
• Reproduction
• Metabolism
• Includes: various hormone secreting glands
Organ System Overview
• Nervous System
– Fast-acting control system
– Responds to internal andexternal change
– Activates muscles andglands
• Includes: brain, spinal cord, peripheral nerves
Organ System Overview
• Muscular System
– Allows locomotion
– Maintains posture
– Produces heat
– Contractibility
• Includes: skeletal, cardiac & smooth muscle
Organ System Overview
• Skeletal System
– Protects internal organs
– Supports body structure
– Provides attachment site for muscles, so they can move
– Site of blood cell formation
– Stores mineral
– Bone is live and functional tissue
• Includes: bones, cartilage, tendons & ligaments
Organ System Overview
• Integumentary System
– Forms the external bodycovering
– Protects deeper tissue frominjury
– Synthesizes vitamin D
– Location of cutaneous (skin)nerve receptors
• Includes: skin, hair, nails,
Organ System Overview
• Reproductive System
– Production of offspring
– Spermatogenesis, oogenesis
• Includes: male/female reproductive organs
– Penis, testes, seminal vesicles
– Mammary glands, vagina, uterus, ovaries & oviducts
Abdominopelvic Major Organs