Physiology Midterm Lecture #1 Flashcards Preview

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Flashcards in Physiology Midterm Lecture #1 Deck (49):
1

Summation

the process of adding up postsynaptic potentials and responding to their net effect
(Occurs in the trigger zone)

2

Temporal summation:

occurs when a single synapse generates EPSPs so quickly that one is generated before other one fades

3

Spatial summation

occurs when EPSPs from several different synapses add up to threshold at an axon hillock

4

Presynaptic Inhibition

- releasesGABA
Prevents voltage-gated Ca2+ channels in synaptic knob (S) from opening and so little or no neurotransmitter is released

5

Functions of the Skeleton

1. Support
2.Protection
3. Movement
4. Electrolyte balance
– calcium and phosphate levels
5. Acid–base balance
6.Blood formation

6

Osteogenic cells

tem cells that give rise to most other types of bone cells

7

Osteoblasts

bone forming cells
– Found under the endosteum and periosteum on the bone surface

8

Osteocytes

osteoblasts that have become trapped in the matrix they deposited
Lacunae cavities where osteocytes reside
Canaliculi–channels connecting lacunae

9

Physiology of Osseous Tissue

-Metabolically active
-phosphorous
-calcium

10

Mineral Deposition (mineralization)

- Crystallization process
- Calcium, phosphate, and other ions are taken from blood and deposited in bone - hydroxyapatite
-osteoblast

11

Mineral Resorption

process of dissolving bone and releasing minerals into blood
-osteoclast

12

Hypocalcemia

deficient calcium in blood
- results in changes in membrane potentials (muscle spasms)
this is caused by vitamin D deficiency

13

Hypercalcemia

- excessive calcium levels results ion channels less responsive

14

What Parathyroid hormones maintain norm blood calcium concentration?

Calcitriol (most active from is VD) and calcitonin

15

Calcitriol raises blood by

increase of Ca by the small intestine
increases Ca by skeleton
kidney reabsorption of Ca

16

Calcitonin decreases blood by

secreting C cells of thyroid glands

17

Homeostasis

the ability to detect change,activate mechanisms that oppose it, and thereby maintain relatively stable internal conditions

18

Claude Bernard (1813–78)

Noted fairly constant internal conditions

19

Walter Cannon (1871–1945)

Coined the term homeostasis

20

Negative Feedback

allows for dynamic equilibrium within a limited range around a set point

21

Heat-losing Mechanism

If too warm, vessels dilate in the skin and sweating begins

22

Heat-gaining mechanism

If too cold, vessels in the skin constrict and shivering begins

23

Homeostasis
Receptor
Integrating center
Effector

Receptor– structure that senses change in the body

Integrating (control) center– processes the sensory information, “makes a decision,” and directs the response

Effector
– cell or organ that carries out the final corrective action to restore homeostasis

24

Positive Feedback and Rapid Change

loop causes a self-amplifying cycle where a physiological change leads to even greater change in the same direction
birthing

25

Nervous system communication:

communicates by electrical and chemical means to send messages from cell to cell

26

Endocrine system communication:

communicates by means of chemical messengers (hormones) secreted into to the blood

27

CNS

Brain and spinal cord
– Enclosed by cranium and vertebral
column

28

PNS

all other nerves besides brain and spinal cord

29

Nerve

a bundle of nerve fibers(axons)
wrapped in fibrous connective tissue

30

Ganglion

a knot-like swelling in a nerve where neuron cell bodies are concentrated

31

Sensory (afferent) Division of the PNS

Carries signals from receptors to CNS

Somatic - carries signals from skin, muscles, joints

Visceral - "" heart, lungs

32

Motor (efferent) division of the PNS

carries signals from CNS to effectors
Somatic - '' skeletal muscles
Visceral - carries signals to glands, cardiac and sm

33

Properties of a Neuron

Excitability- ability to respond to a stimuli

Conductivity- produce electrical signals to other cells

Secretion - secretes a neurotransmitter

34

Dendrites:

Primary site for receiving signals from Nucleus other neurons

35

Soma:

control center of neuron – aka cell body

36

Axon (nerve fiber)

Specialized for rapid conduction of signals to distant points

37

Synaptic knob (terminal button):

junction (synapse) with the next cell

38

Myelin Sheath

Formed by oligodendrocytes in CNS and Schwann cells in PNS

39

Electrophysiology

study of cellular mechanisms for producing electrical potentials and currents

40

Electrical Potential

a difference in concentration of charged particles between one point and another

-cells are polarized, more negative on the inside of the membrane than outside

41

Electrical Current

a flow of charged particles from one point to another

42

Resting Membrane Potential

due to the unequal distribution of ECF and ICF


1. Ions diffuse down their concentration
gradient
2. Plasma membrane is selectively permeable
3. Electrical attraction of cations (+) and anions (-) to each other

43

Characteristics of Actions potentials

1. All or None
2. Nondecremental - does not get weaker with distance
3. Irreversible

44

Refractory Period

a few ms after it is difficult or impossible to stimulate that region. The period of resistance to restimulation

45

Absolute refractory period

no stimulus of any strength will trigger AP
last as long as inactivated Na+ gates are closed

46

Relative refractory period

Only very strong stimulus will trigger new AP,

last until hyper-polarization ends

47

Saltatory Conduction

signal seems to jump from node to node

48

Speed Conduction of Nerve Fibers

Diameter of fiber - large fibers have increased SA = more rapid signals

Myelin = faster signal conductions

49

What ions are more abundant inside and outside the cell?

K+ concentration is higher inside the cell
Na+ is higher outside the cell