biology > ch 8 > Flashcards

ch 8 Flashcards

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1
Q

define homeostasis

A

equilibrium between an organism’s physiological functions + between the organism and its environment

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2
Q

homeostasis is a balance in response to continually changing conditions in both the ___ and ___ environments

A

internal and external

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3
Q

define dynamic equilibrium

A

when an organism remains stable with fluctuation limits

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4
Q

when an organism can’t maintain its balance:

A

death

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5
Q

3 components of homeostatic control centres

A
  1. monitor
  2. coordinating centre
  3. regulator
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6
Q

3 components of homeostatic control centres: MONITOR

A

special sensors in the organs that detect changes in homeostasis

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7
Q

3 components of homeostatic control centres: COORDINATING CENTRE

A

receives message from sensors and relays info to appropriate regulator

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8
Q

3 components of homeostatic control centres: REGULATOR

A

organ/tissue that restores normal balance

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9
Q

process of homeostatic control system

A
  1. stimulus disrupts homeostasis
  2. (controlled condition monitored by) receptors send to control centre
  3. control centre provides effectors that respond to alter condition
  4. return to homeostasis when response brings controlled condition back to normal
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10
Q

the activity of some specialized parts of an animal are coordinated by the TWO MAJOR SYSTEMS OF INTERNAL COMMUNICATION:

A
  1. nervous system (involves high-speed messages)
  2. endocrine system (involves production, release, and movement of chemical messengers)
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11
Q

all animals exhibit coordination by chemical signals: ___, ___, and __

A
  • hormones
  • pheromones
  • neurotransmitters
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12
Q

chemical signals: hormones

A
  • produced by endocrine system
  • communication between organs of the body
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13
Q

chemical signals: pheromones

A
  • communicate between different individuals
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14
Q

chemical signals: neurotransmitters

A
  • between cells, locally (short distances; between neurons)
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15
Q

negative feedback systems prevent

A

small changes from becoming too large

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16
Q

negative feedback systems:

A
  • most homeostatic control systems (body self correcting)
  • response is opposite to stimulus
  • decreases an action, stops when back to normal
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17
Q

positive feedback systems ___ a small effect

A

amplify

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18
Q

positive feedback systems:

A
  • response is same as stimulus
  • leads to instability and possibly death
  • must be turned off by outside event
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19
Q

positive feedback system: example

A
  • blood clotting
  • childbirth
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20
Q

negative feedback system: example

A
  • if body temperature changes, system restores normal levels
  • Blood sugar regulation: insulin lowers blood glucose when levels are high
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21
Q

the brain is the ___ of the body

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A

control centre

22
Q

brain + nervous system:

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A
  • uses nervous system as interface w external environment and control system for internal environment
  • monitors and controls bodily processes
  • brain, spinal cord, and nerves that emerge and connect to rest of body
  • brain contains more than 100 billion nerve cells (each nerve can have up to 10,000 connections w other nerve cells)
23
Q

nervous system divided into

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A
  • central nervous system (CNS) (brain and spinal cord) (integrates and processes info from nerves)
  • peripheral nervous system (PNS) (network of nerves carrying sensory messages to CNS and sending info from CNS to effectors: muscles and glands) (subdivisions: AFFERENT and EFFERENT systems)
24
Q

PNS: afferent system

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A

carries TOWARDS
- receives input from receptors and transmits to CNS by AFFERENT NEURONS (sensory neurons: carry impulses from sensory receptors to CNS)

25
PNS: efferent system
carries AWAY - efferent neuron carries impulses from CNS to effectors (muscles + glands) - further subdivided into SOMATIC and AUTONOMIC systems
26
PNS: efferent system: SOMATIC SYSTEM
made of efferent (motor) neurons that carry signals to skeletal muscles in response to external stimuli
27
PNS: efferent system: AUTONOMIC SYSTEM
controls involuntary processes - communicates w effectors (smooth muscles and glands) - further divided into SYMPATHETIC and PARASYMPATHETIC NERVOUS SYSTEM
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PNS: efferent system: autonomic system: SYMPATHETIC DIVISION
- increases energy consumption and prepares body for action - dominates in situations with STRESS, danger, excitement, strenuous physical activity
29
PNS: efferent system: autonomic system: PARASYMPATHETIC DIVISION
- stimulates body activities that acquire and conserve energy - dominates during quiet, low-stress situations (e.g. relaxation)
30
two kinds of cells in nervous system:
neurons/nerve cells and glial cells
31
cells of nervous system: NEURONS/nerve cells
- structural + functional (specialization: respond to physical/chemical stimuli, conduct electrochemical signals, release chemicals that regulate body processes) - made of nucleus, cell body, dendrites, axons - organized into nerves (tissues)
32
neurons have the same features as
other body cells (cell membrane, cytoplasm, etc) - types differ in shape, size, but share four common features
33
common features among neurons:
1. dendrites (dendros = tree) 2. cell body 3. axon 4. axon terminal (branching ends)
34
common features among neurons: DENDRITES
branched projections which form TREELIKE OUTGROWTH at one end of neuron - receive nerve impulses/signals and transmit towards cell body
35
common features among neurons: CELL BODY
contains nucleus and most organelles - site of cell's metabolic reactions - processes input from dendrites (if input is big enough, it's relayed to axon and an impulse is initiated)
36
common features among neurons: AXON
specialized projection that conducts impulses away from cell body to another neuron/effector - terminal end branches into fibres - branching end as small button-like swellings: AXON TERMINALS most axons are bundled together as NERVE FIBRES/NERVES - nerves branch to relay signals throughout periphery of ENTIRE BODY
37
common features among neurons: AXON TERMINAL (branching ends)
releases chemical signals into space between neuron and receptors/dendrites of neighbouring cells
38
what are nerves
- variously-sized many axons that form nerve fibres - branch extensively to relay signals throughout periphery of entire body
39
neuron support system: glial cells
- support cell of nervous system - do not conduct electrical signals - nourish neurons, remove their wastes, and defend against infection - provides a supporting framework for all nervous system tissue
40
neuron support system: glial cells: SCHWANN CELLS (main glial cells)
- form myelin by wrapping themselves around axons
41
neuron support system: glial cells: MYELIN SHEATHS (formed by glial cells)
- fatty, insulating layer around axons (gives them white, glistening appearance) - protects neurons and speeds up the rate of nerve impulse transmission
42
neuron support system: glial cells: NODEDS OF RANVIER
- regularly occurring gap between sections of myelin sheaths along axon - expose axon membrane directly to extracellular fluids - speeds up the rate at which electrical impulses move along axons
43
neural signalling
communication by neurons - reception, transmission, integration of nerve impulses by neurons and response to these impulses
44
neural signalling process: reception
detection of stimulus, performed by neurons and by specialized sensory receptors (in eyes and skin)
45
neural signalling process: transmission
movement of message along neuron to either another neuron or muscle or gland
46
neural signalling process: integration
sorting and interpretation of multiple neural messages and determination of appropriate response
47
neural signalling process: response
output or action
48
neural signalling process: THREE FUNCTIONAL CLASSES OF NEURONS:
- afferent neurons (sensory neurons) - interneurons - efferent neurons
49
neural signalling process: THREE FUNCTIONAL CLASSES OF NEURONS: afferent neurons (sensory neurons)
transmit stimuli collected by their sensory receptors to interneurons in CNS
50
neural signalling process: THREE FUNCTIONAL CLASSES OF NEURONS: interneurons
integrate neural message and relay impulses between afferent and efferent neurons, found primarily in brain and spinal
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