ANP 1105 Study Guide - Midterm Guide: Facilitated Diffusion, Passive Transport, Negative Feedback
14 Nov 2018
School
Department
Course
Professor
HOMEOSTASIS AND DIFFUSION LECTURE
What are the 4 types of passive transport mechanisms?
1. Simple diffusion
2. Osmosis
3. Facilitated diffusion
4. Filtration
Definition of diffusion
• Tendency of molecules or ions to scatter evenly throughout the environment
• Diffusion is based on gradient slope (high to low concentration), molecular size,
and temperature
What is homeostasis, and what are some examples?
• A system in which variables are regulated so that internal conditions remain
relatively constant
• Examples: temperature regulation, blood ion concentration
• Translation of homeostasis is unchanging but it is actually a dynamic state in
which conditions vary but within narrow limits, this involves many systems:
o Adequate blood levels of vital nutrients
o Heart activity/blood pressure monitored and adjusted as needed
What are the 3 essential components of a homeostatic control mechanism?
1. Receptor: senses change (stimulus) and sends info (afferent pathway) to…
2. Control center: determines set point for variable maintenance, analyzes info and
determines correct response
3. Effector: provides means for response (output along efferent pathway)
• Feedback: negative or positive allows for regulation within a range/enhanced
response
Negative feedback mechanisms
• Output reduces or shuts off stimulus
• Goal of negative feedback is to prevent sudden, severe changes
• 1 hormone regulating a process: negative feedback secretion
• process regulated in opposite directions by 2 different hormones: ex. blood
glucose
• Example: As blood sugar rises, receptors in the body sense this change, and the
pancreas (the control center) secretes insulin into the blood. This change in turn
prompts body cells to absorb more glucose, removing it from the bloodstream. As
blood sugar falls, the stimulus for insulin release ends
Positive feedback mechanisms
• Response of mechanisms enhances original stimulus so output is further
stimulated
• Change occurs in the same direction as the original response
• Goal is to be attained, often called a cascade (amplifies original stimulus)
• Example: oxytocin causes contractions to become more frequent and powerful,
and these contractions causes more oxytocin to be released, and so on until the
baby is born
• Example: blood clotting
Homeostatic imbalance
• Most diseases are seen as a disturbance of homeostasis = homeostatic imbalance
• Aging is associated with progressive decrease in our ability to maintain
homeostasis therefore greater risk for illness
What regulates body temperature?
• The control center for regulating body temperature is the hypothalamus of the
brain. When the body is fighting an infection, the hypothalamus allows body
temperature to climb higher than the normal value of 38C, this process involves
both positive and negative feedback, good to have the balance fluctuate a bit so
that you are able to battle off infection
What is the autonomic nervous system?
• Auto = self, nom = govern
• System of motor neurons to smooth muscle, cardiac muscle, and glands allow
responses usually without our awareness
• Also called involuntary NS and general visceral motor system
• Both an afferent and efferent system because it has both sensory input and motor
output
• 2 divisions of the ANS which is the parasympathetic NS and sympathetic NS
What are the differences and similarities in the ANS and somatic NS?
• Similarities:
o Both have motor fibers
o Both systems are controlled by higher brain centers
• Differences:
o Their effectors
o Their efferent pathways and ganglia
o Their target organ responses to their neurotransmitters
Document Summary
What are the 4 types of passive transport mechanisms: simple diffusion, osmosis, facilitated diffusion, filtration. Definition of diffusion: tendency of molecules or ions to scatter evenly throughout the environment, diffusion is based on gradient slope (high to low concentration), molecular size, and temperature. This change in turn prompts body cells to absorb more glucose, removing it from the bloodstream. As blood sugar falls, the stimulus for insulin release ends. Homeostatic imbalance: most diseases are seen as a disturbance of homeostasis = homeostatic imbalance, aging is associated with progressive decrease in our ability to maintain homeostasis therefore greater risk for illness. What regulates body temperature: the control center for regulating body temperature is the hypothalamus of the brain. Motor fibers are thick and heavy myelinated, conduct nerve impulses rapidly, no ganglia required: ans: uses a 2 neuron chain. The cell body of the first neuron (preganglionic neuron) resides in brain stem or spinal cord.
