Download Class 3 The Human Body

The Human Body
- Introduction
Homework: Review Body Atlas Pg. 223-232
Study slides and notes for quiz next week
Body Systems
Structural
Organization
• Atoms – molecules – cell
organelles – cells – tissues –
organs – systems – person
Cells
• The smallest living unit in us
• 100 trillion in body
• 10x bacteria in and on us
• Need to reproduce
• Need to perform their work
• Need to live and die “healthy”
Maintaining Life –
External Boundaries
• Interdependence of all systems and
their organs, tissues, and cells
• Boundaries from environment
• Intensely separate but highly
interactive (selective) with outside
environment
• Keeps out physical and chemical
factors, microbes, dryness, and
radiation. Regulates temperature
• Integumentary System (skin, hair, nails)
• The external boundaries on the inside
– membranes and immune system
Maintaining Life – Internal Boundaries
• Internal boundaries also exist throughout the body to separate
systems, organs, tissues, cells yet allow them to interact with each
• Internal Boundaries created by
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Body cavities
Organ membranes, tissue membranes, and cell membranes
Cell compartments
Cytoskeletons
Internal Boundaries in the body and cell
Maintaining Life - Movement
• Macro movement
• Muscular System
• Skeletal System
• Internal System movement
• Blood, Urine, Respiration, Digestion, smooth muscle (heart, stomach, etc)
• Micro movement – cellular movements
• Cell generation
• Cell machinery
• Immune cells
Maintaining Life – Other Factors
• Digestion
• breakdown of food, also used at cellular level (catabolism)
• Metabolism
• All chemical reactions that occur in the body – anabolism, catabolism, power
(ATP synthesis)
• Excretion – waste disposal through respiratory, digestive, and urinary
systems
• Growth
• Reproduction
Maintaining Life - Responsiveness
• Stimuli → Response (effect)
• Response occurs at system, tissue, cell, etc
• Macro
• e.g. Injure hand – reflex
• e.g. Cut – vessels contract
• Homeostasis
• e.g. Temperature, Blood Pressure, CO2
Homeostasis - definitions
1. The body’s ability to maintain relatively stable internal conditions
even though the outside world changes continuously
2. A dynamic state of equilibrium or balance in which internal
conditions vary, but always within relatively narrow limits
3. When the body’s needs are adequately met and it is functioning
smoothly
4. Sickness is a lack of homeostasis
Homeostatic Precision
• Monitoring of “normal”
• Continually adjusts to normal by helping or hindering body processes
• Communication of this occurs through the
• Nervous System
• Endocrine System
Examples Targets (variables) for Homeostasis
• Hundreds of variables
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Body Temperature
Blood Pressure (BP), Heart Rate
Breathing, Blood Oxygen
Blood Volume
Blood Chemistry (e.g. Sodium levels, acid-base)
Homeostatic Components
• Stimulus – outside influence
• Variable– the factor or event being regulated
• Receptor
• Monitors environment and responds to stimuli (changes)
• Sends messages through afferent pathway
• Control Center
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Receives messages from receptor
Compares to set point (normal)
Determines correct response
Messages effector through efferent pathway
• Effector
• Body components that respond to Control Center
• Feedback (back and forth) through whole process
Homeostasis
Response to cold
Stimulus: Decreased room temp
Variable: Core body temperature
Receptor: Hypothalamus
Control: Brain
Effectors?
Response?
Negative Feedback Mechanisms
• Most responses are negative feedback (to push against the stimuli)
• Reduce or negate effect of stimuli
• Variable (target) goes in opposite direction
Positive Feedback
Mechanisms
• Infrequent events not requiring
continual adjustment are under
positive feedback
• Contractions during labor
• Blood Clotting
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Amplify or cascade effect
Allows effect of stimuli to increase
Variable deviates farther from origin
Negative feedback systems in place
to turn off positive mechanisms
Analogies to the Body of Christ – His Church
• Separate systems, organs, tissues, and cells
• All separate but meant to be highly integrative
• Love for one another is the integration – active love
• Homeostasis
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Jesus is the control center
We are or the church is the variable
Effects His children and churches as necessary to get to the “set point”
The life and character of Jesus is our “set point” that God wants in us
Our character – negative feedback loop
His love to others through us – positive feedback loop