Midterm 2 Flashcards
What is homeostasis?
Ability to maintain a consistent internal environment so cells can function properly, even if the external environment changes
All organs work to maintain the internal environment
What is a homeostatically regulated variable?
The regulated variable has a sensor within the body, kept in range by physiological mechanisms (blood pressure) , operate continuously
Example of non-homeostasis variable
Heart rate
Parts of a negative feedback system? (5)
Set point, sensor, error detector, integrator, effector
Set point?
Normal range for regulated variable
Sensor?
Detects value, tranduces into some kind of stimulus
Error detector?
Compares actual value to set point
Integrator?
Interprets error and determines output of effectors
Effector?
Change value of regulated variable
Example of loss of homeostasis?
Diabetes, When homeostasis lost for one variable, it can trigger changes in other variables
Negative feedback?
returns variable to set point
Positive feedback?
pushes variable away from set point
Feed forward control?
anticipatory, minimizes changes to variable
What is the ANS?
Consists of motor neurons that innervate smooth muscle, cardiac muscle, glands
Makes adjumesnts to body as needed (shunts bloods, heart rate, digestive process)
Subconscious, also called involuntary nervous system or visceral motor system
ANS is part of the ______ pathway
Efferent, Motor
Both somatic and autonomic contain motor fibers but differ in?
Effectors, Efferent pathways/ ganglia, Target organ responses
Somatic nervous system?
Skeletal muscle, Cell body in CNS, myelinated axon travels in spinal/ cranial nerves to skeletal muscle
All somatic neurons release Ach (always stimulatory)
Autonomic nervous system?
Cardiac, smooth muscle, glands
Preganglionic: CNS: thick myleinated axon (ganglion)
Postganglionic: PNS: non-myleinated to effector
Pregang. Release AChm postgang. Release NE or ACh
What does dual innervated mean?
Visceral organs served by both divisions, with opposite effects
Parasympathetic?
Rest and digest, conserves energy, maintenance,
Sympathetic?
Fight or flight, mobilizes body, emergency
Anatomy of parasympathetic?
Crainoscaral, brain stem, sacral spinal cord
Long preganglionic, short postganglionic
Glangia near visceral effector organ
Anatomy of sympathetic?
Thoracolumbar, thoracuic, lumbar spinal cord
Short preganglionic, long postganglionic
Glanglia close to spinal cord
Para/sym. in sex?
Parasympathetic fibers cause erection or penis/ clitoris, sympathetic fibers cause ejactualtion of semen or contraction of vagina
Sympathetic tone?
BVs only innervated by sympathetic fibers, controls blood pressure, continual state of partial constriction
Blood goes where needed, Vasoconstriction of skin BVs minimizes bleeding during injury
Parasympathetic tone?
Tone slows heart, dictates activity of digestive tracts, activates most glands
Sympathetic can override during stress, some drugs block parasympathetic responses
3 other features of the sympathetic system?
Thermoregulatory in response to heat
Release renin from kidneys
Metabolic effects
Localized vs. diffuse effects?
Para.- short lived, ACH destryoed by ACHe
Symp- longer, NE and epinephrine take long time to come down
Brain stem and SC?
Reticular formation, medulla, relflexes
Hypothalamus?
Main integrative center, Heart rate, BP, emotional responses, activates fight or flight
Cerebral cortex?
Cortical input may modify ANS, works through limbic system
Disorders of the ANS? (2)
Hypertension (high blood pressure), ulcers (decreased blood to stomach wall)
What is smooth muscle?
alls of most hollow organs (respiratory, digestive, urinary, repoprductive, not in heart)
Sheets of tightly packed fibers
2 layers of smooth muscle?
Longitudinal- Run length of organ, when shortened shorten length
Circular layer- fiber runs arounds diameter of organ, when shortened shorten diameter
Gives contraction of GI tract to pass food
Components of muscle cells?
Thinner, shorter, Single nucleus, No striations, not alot of extracellular matrix tissues
Muscle cell axons contain…
varicosities, swellings which store and release NT’s into synaptic cleft/diffuse junction
2 types of muscle?
Unitary/ visceral, or multiunit
Unitary muscle?
All hollow organs minus heart
Has spontaneous action potentials, can contract on its own/ depolarize without external stimuli
Electrically coupled by gap junction, chemically stimulated
Multiunit muscle?
Large airways of lungs, large arteries, iris
No gap junctions, no spontaneous depolarization
Controlled by ANS, hormones
What is the intermediate filament network?
No contractile proteins, form lattice-like network
Transmit tension generated by contractile proteins to the sarcolemma
When actin and myosin contract energy is transmitted to IFN
How are filaments arranged?
Thin/ thick filaments arranged diagonally, connected by dense bodies to eachother and to intermidate filaments, for every thick filament their are 13 thin
How is contraction regulated? (4 steps)
Contraction regulated by Ca, but no T tubular system, less complicated SR
SR stores Ca but also comes from outside
Caveolae contain voltage gated Ca channels
Ca entry triggers Ca release form SR
4 steps of contraction?
Ca binds to calmodulin (CaM)
Causes inactive mysoin light chain kinase (adds phosphate group to something)
Binds to myosin, makes it active
Phosphorylates with mysoin cross bridge (can bind with actin)
What stimulates contraction?
Neural (nervous control/action potential), hormones
If you stretch smooth muscle it will…
immediately contract (stretch activated channels)
Contracts briefly, adapts to new length (allows organ to have huge volume changes)
Contraction speed of smooth muscle? (3 reasons)
Contraction speed: Slower to contract and relax
Slower ATPases
Each crossbridge lasts longer
Ca pumped more slowly
Elements of the endocrine system?
Activates with NS to coordinate, hormones released into blood with slower responses but longer lasting
Controls and integrates reproduction and development, blood-water nutrient balance, mobilizes body defenses
Examples of endocrine glands
Pituitary, thyroid, parathyroid, adrenal, pineal
Hypothalamus (neuroendocrine)
Pancreas, gonads, placenta (endocrine/ exocrine)
Also found in adipose cells, thymus, kidneys