Homeostasis and autonomic nervous system Flashcards

1
Q

What are the 5 steps in homeostatic balance?

A
  1. stimulus
  2. receptor
  3. input
  4. output
  5. response
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2
Q

What is homeostasis?

A

the maintenance of relatively stable internal conditions despite continuous changes in the environment.

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3
Q

What is dynamic state of equilibrium?

A

a balance or steady state, in which internal conditions are constantly adjusting to changes but kept within relatively narrow limits.

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4
Q

What is law of mass balance?

A

a steady state in which the total amount of a substance the body takes in must be equal to the amount it loses
- ensures total amount of substance in body remains constant

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5
Q

What are the 2 main regulator organs and what is the variable?

A
  • nervous and endocrine
    V: the factor being regulated in the system (blood sugar, body temp etc.)
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6
Q

What are the 3 homeostatic control variables?

A

receptor, control center, effector

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7
Q

Explain receptor, control center and effector.

A

R(sensor): Monitors environment, responds to stimuli—changes in a variable that evoke a response, Sends information to the control center (input)
C: Receives input from receptor, determines set point (range of levels which a variable is maintained) and appropriate response to input, sends information to the effector (output)
E: Receives output from control center, provides the means to respond (via muscle or gland), response either reduces (negative feedback) or enhances (positive feedback) the effect of the stimulus

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8
Q

What is a negative feedback mechanism?

A

Uses the afferent and efferent pathways
- response reduces or shuts off original stimulus
- variable changes in the opposite direction of initial change, bringing it back to original state

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9
Q

What are some examples of negative feedback?

A
  • regulation of body temperature (nervous system)
  • regulation of blood glucose by insulin (endocrine system)
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10
Q

What is a positive feedback mechanism?

A

Response enhances or exaggerates the original stimulus
- change in the same direction of initial change

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11
Q

Examples of positive feedback.

A
  • enhancement of labor contractions by oxytocin
  • platelet plug formation and blood clotting
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12
Q

What is homeostatic imbalance?

A

a disturbance of homeostasis
- increases risk of disease
- contributes to changes with aging (system becomes less effective)
- if negative is overwhelmed, positive may take over (e.g., heart failure)

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13
Q

What is the automatic nervous system (ANS) also called and visceral motor system?

A
  • involuntary NS
    consists of motor neurons that:
  • innervate smooth and cardiac muscles and glands
  • adjusts to ensure optimal support (heart rate, blood pressure, digestive processes)
  • operate via subconscious control
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14
Q

What is different between the somatic and autonomic nervous system?

A
  • effectors
  • number of neurons between CNS and the effectors
  • actions of their neurotransmitters at the effectors
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15
Q

Describe the SNS.

A
  • cell body is in CNS and a single, thick myelinated group A axon extends in spinal or cranial nerve directly to skeletal muscle
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16
Q

What are the 2 pathways in the ANS?

A
  1. preganglionic neuron: cell body in CNS with thin, lightly myelinated preganglionic axon extending to ganglion
  2. postganglionic neuron (outside CNS): cell body synapses with preganglionic axon in autonomic ganglion with nonmyelinated postganglionic axon that extends to effectors
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17
Q

What is released in the ANS and what is their effect?

A

preganglionic fibers: release ACh
postganglionic fibers: release norepinephrine (sym) and ACh (para)
- can be excitatory or inhibitory - depending on the receptor

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18
Q

what fibers do most spinal and cranial nerves contain?

A

somatic and autonomic fibers

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19
Q

What are the 2 arms of the ANS?

A

Parasympathetic division: promotes maintenance functions, conserves energy
Sympathetic division: mobilizes body during activity

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20
Q

What is dual innervation?

A

all visceral organs are receive input from both (para and sym), they are both partial active to counter balance and maintain operations
- Dynamic antagonism between two divisions maintains homeostasis

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21
Q

What does the sympathetic system do?

A
  • mobilizes body during activity
  • fight- or - flight
  • exercise, excitement, emergency and embarrassment activate SS
  • Effects: heart rate, dry mouth, sweaty skin, dilated pupils, increased blood pressure, dilated bronchioles, liver releases glucose.
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22
Q

What is the difference in the site of origin in the sym and para?

A

S: are thoracolumbar; originate in thoracic and lumbar regions of the spinal cords
P: are craniosacral; originate in brain and sacral spinal cord

23
Q

What is the difference in the lengths of fibers in the sym and para?

A

S: are short preganglionic and long postganglionic

P: long preganglionic and short postganglionic

24
Q

What is the difference in the location of ganglia in the sym and para?

A

S: ganglia lie close to spinal cord
P: ganglia are located in or near the visceral effectors

25
Q

How is branching different in pre and post ganglionic fibers?

A

pre: minimal branching
post: extensive branching

26
Q

What parts of the CNS effects the ANS?

A

brain stem and spinal cord, hypothalamus, and cerebral cortex

27
Q

What are the effects of cerebral input?

A
  • modify the ANS but not subconsciously
  • works with the limbic system
28
Q

What does the brain stem and spinal cord control?

A

BS: regulates ANS through reticular formation
- medulla center regulates heart and vessel diameter, gastrointestinal activates
- midbrain controls muscles of pupil and lens
SC: controls defection and urination but are subject to conscious override

29
Q

What does the hypothalamus control?

A
  • ant regions direct para functions; post region directs sym
  • control may be direct or indirect through reticular system or spinal cord
  • controls: heart activity, blood pressure, temp, water balance, and endocrine activity
30
Q

How does the hypothalamus effect emotional responses?

A

Activated through the limbic system signals hypo to cortical controls (motor cortex)
- connections of hypo to limbic lobe allow cortical influence on ANS
- voluntary cortical control of some visceral activities is possible

31
Q

What are the voluntary cortical control?

A

biofeedback: awareness of physiological conditions with goal of consciously influencing them
- allows some people to control their migraines and manage stress

  • activates fight-or-flight
32
Q

What are the 3 conditions?

A

Hypertension (high blood pressure) - heart in over drive

Raynaud’s disease - fingers turn white, then cyanotic

Autonomic dysreflexia - life threating activation of auto neurons in quadriplegics and people with injury above t6 - blood pressure is high (stroke)

33
Q

What does the endocrine system control?

A

Reproduction
- growth and development
- maintenance of electrolytes, water and nutrient balance in blood
- regulation of cellular metabolism and energy balance
- mobilization of body defenses

34
Q

What is the difference between endo and exo crine glands?

A

EN - produces hormones - lack ducts
EX - produce nonhormonal substances (sweat, saliva) - have ducts to carry secretion to membrane surface

35
Q

What is a hormone and what are the 2 types?

A

Hormones: long-distance chemical signals; travel in blood or lymph
- Autocrines: chemicals that effects the same cells that secrete them
- Paracrines: locally acting chemicals that affect cells other than those that secrete them
- Autocrines and paracrines are local chemical messengers; not considered part of endocrine system

36
Q

What are the 2 major classes of hormones and 1 lesser class?

A

Amino acid–based hormones
- Amino acid derivatives, peptides, and proteins
Steroids
- Synthesized from cholesterol
Eicosanoids
- considered a hormone by some but not others

37
Q

Which hormones use second messengers?

A

amino acid-based hormones

38
Q

What are the 2 main second-messenger systems?

A

cyclic AMP
PIP2-calcium

39
Q

Explain cAMP?

A
  • phosphorylated proteins are then either activated or inactivated
  • cAMP is degraded by enzyme phosphodiesterase, stopping cascade
40
Q

What is the difference between water and lipid soluble hormones?

A

W - amino acid based except thyroid - act on plasma receptors and G protein - can’t enter cell
L - steroid and thyroid - acts on intracellular receptors to directly activate genes - can enter cell

41
Q

What are the 3 types of way the endocrine glands are simulated?

A
  • humoral (fluid)
  • neural (neurons)
  • Hormonal (hormones)
42
Q

What are the 2 triggers of hormone release?

A
  • endocrine gland stimuli
  • nervous system modulation
43
Q

How is the hypothalamus connected to the pit gland?

A

infundibulum

44
Q

What is the post pit and what does it make up?

A

composed of neural tissue that secretes neurohormones
- post lobe and infundibulum make the neurohypophysis

45
Q

what are the direct and indirect actions of the GH?

A

D - metabolic processes: Increases blood glucose and increases fat breakdown and release
ID - growth

46
Q

What is the difference between: Hypersecretion - gigantism and acromegaly and Hyposecretion - pituitary dwarfism

A

G - excess lengthening of bones; 8ft
A - excess thickening of bones in hands, feet, and face
PD - deficient bone lengthening - 4 ft

47
Q

Explain what ACTH is stimulated/ inhibited by and the target organ?

A

S - CRH (corticotropin releasing hormone)
I - feedback from glucocorticoid
TO - adrenal cortex

48
Q

Explain what LH is stimulated/ inhibited by and the target organ?

A

S - GnRH (gonadotropin releasing hormone)
I - feedback from estrogen, progesterone, or testosterone
TO - gonads

49
Q

Explain what FSH is stimulated/ inhibited by and the target organ?

A

S - GnRH (gonadotropin releasing hormone)
I - feedback from estrogen or testosterone
TO - gonads

50
Q

Explain oxytocin is stimulated/ inhibited by and the target organ?

A

S - stretching cervix, suckling
I - stress, lack of stimuli
TO - uterus, breast

51
Q

Explain what PRL is stimulated/ inhibited by and the target organ?

A

S - decreased PIH, estrogen, suckling
I - PIH (prolactin inhibiting hormone)
TO - breast

52
Q

Explain what ADH is stimulated/ inhibited by and the target organ?

A

S - increased solute conc., low blood volume
I - alcohol, hydration
TO - kidney

53
Q

Explain what GH is stimulated/ inhibited by and the target organ?

A

S - low GH, deep sleep, low BG, exercise
I - increase GHIH, decrease GHRH, feedback by GH and IGF

54
Q

Explain what TSH is stimulated/ inhibited by and the target organ?

A

S - TRH (thyrotropin releasing hormone), cold temps
I - GHIH, feedback from thyroid hormone
TO - thyroid glands