ANP1105 Homeostasis Flashcards
What is Homeostasis
the ability to maintain relatively stable internal conditions even though the outside world changes continuously.
REMAIN @ AN EQUILIBRIUM
What two systems play a major role in maintaining homeostasis?
Nervous and Endocrine
What do the nervous and endocrine systems use to communicate within the body?
Neural electrical impulses or bloodborne hormones, as information carriers
The VARIABLE – of at least three components that work together for homeostasis
- Receptor
- Control Center
- Effector
Receptor
Senses change (STIMULUS) and sends info (AFFERENT PATHWAY) to the control center
Control Center
Determines the SET POINT (normal level) for variable maintenance
and
Receives and analyzes INPUT from RECEPTOR and DETERMINES appropriate response
Effector
Receives OUTPUT from Control Center
Provides means for response
Feedback (negative feedback) or enhances stimulus (Positive feedback) allows for regulation within a range/enhances response
Negative Feedback Mechanisms
- MOST USED feedback mechanism
- response REDUCES or SHUTS OFF original stimulus
What is the goal of a negative feedback mechanism?
Prevent sudden, sever changes
Examples of stimuli
Heat or Cold
What is an example of a negative feedback mechanism
Thermoregulation: This is what our bodies do to regulate our temperature
Positive Feedback Mechanism
Response ENHANCES or EXAGGERATES the original stimulus, so the output is further stimulated, occurs in the SAME DIRECTION as original response
What is an example of a positive feedback mechanism?
Blood clotting - add more to spot that is broken (more platelets are added)
Contractions and birth
Homeostatic imbalance
A DISTURBANCE of homeostasis
What is a change associated with homeostatic imbalance?
Aging!
When control systems become less efficient, there is a greater risk for illness
Autonomic nervous system
This is a system of motor neurons
- also called involuntary nervous system or general visceral motor system
- innervate (supplies) smooth muscles, cardiac muscle, and glands
Somatic VS Autonomic
Somatic – effects Skeletal muscle, Always stimulatory
Autonomic – effets Smooth muscle, Stimulatory or Inhibitory
Somatic - specifics
Has a thick, myelinated axon from spinal cord to skeletal muscle; rapid conduction of impulses (no ganglia)
ACh is the NT at effector
ANS
Has both Sympathetic and Parasympathetic neurons
Has a Two-neuron chain from CNS to effector organs
Parasympathetic neuron
ACh is the NT
Has a LIGHTLY myelinated preganglionic axon
and a NON-myelinated postganglionic axon
Sympathetic neuron
LIGHTLY myelinated preganglionic axons, NON-myelinated postganglionic axon
as well as going to blood vessels – produces NE (neon)
Parasympathetic division
REST and DIGEST (more regulation)
“D” system: digestion, defecation, diuresis
Sympathetic division
FIGHT or FLIGHT
“E” system: exercise, excitement, emergency, embarrassment
True or false - Visceral organs have dual innervation/counterbalance one another
TRUE
Give an example of a cooperative interaction
regulation of external genitalia during intercourse
PNS: dilation of blood vessels in penis/clitoris
SNS: ejaculation, reflex contraction of females vagina
Roles of SNS
- Thermoregulatory responses to heat
- Renin release from kidneys (increases blood pressure)
- Metabolic effects (e.g. raises blood glucose levels, increases mental alertness)
Anatomical differences between ANS divisions
- sites or origin or nerves
- Relative lengths of pre- and post- ganglionic fibers
- locations of ganglia
Brain Stem and Spinal Cord Controls
- motor centres in ventro-lateral medulla (eg. heart rate, blood)
- spinal cord controls defecation and micturition but are subject to conscious override
Hypothalamic Controls
Hypothalamus = integration centre of ANS
Cortical Controls
eg: biofeedback to improve management of migraine headaches, stress and cardiac function
In the Endocrine system, what are the 5 things it controls and integrate?
- reproduction
- growth and development
- maintenance of electrolyte, water, and nutrient balance of blood
- regulation of cellular metabolism and energy balance
- mobilization of body defenses
What is the main difference between Endocrine gland vs Exocrine glands
Endocrine glands secrete substances directly into the Bloodstream whereas exocrine glands secrete substances into a ductal system to an epithelial surface
What is a hormone?
a chemical substance released into the ECF that regulates the metabolic function of the other cells in the body
