Homeostasis Flashcards
(102 cards)
1
Q
What are the three main components of the nervous system?
A
the brain, spinal cord, and nerves
2
Q
What is the central nervous system?
A
takes in and processes information, coordinates a response
3
Q
What is the peripheral nervous system?
A
relays signals to and from the CNS
4
Q
What are the three main types of neurons?
A
sensory, interneuron, motor
5
Q
What are glial cells?
A
specialized cells that provide support for neurons
6
Q
What are the three structural types of neurons?
A
multipolar, bipolar, and pseudounipolar
7
Q
What are multipolar neurons?
A
neurons with many dendrites and one axon, cel body near the dendrites
8
Q
What are bipolar neurons?
A
one dendrite, one axon, cell body in the middle
9
Q
What are pseudounipolar neurons?
A
Cell body with one extension split into two axons with no dendrites
10
Q
What are sensory neurons?
A
also called afferent neurons, transmit signals from sensory receptors to the CNS
11
Q
What are interneurons?
A
also called association neurons, transmit signals between sensory and motor neurons, only in the CNS
12
Q
What are motor neurons?
A
also called efferent neurons, transmit signals from CNS to effectors
13
Q
What are nerves?
A
bundles of axons wrapped in connective tissue and fat, found in the PNS
14
Q
What are sensory nerves?
A
transmit signals from sensory organs to the CNS
15
Q
What are motor nerves?
A
transmit impulses from CNS to effectors
16
Q
What are mixed nerves?
A
transmit signals to and from the CNS
17
Q
What is a reflex?
A
a rapid, automatic response that bypasses the brain (via spinal cord)
18
Q
What is the reflex arc?
A
pathway that goes from a sensory receptor at the end of a sensory neuron, to an interneuron in the spinal cord, to a motor neuron, an then to an effector
19
Q
What is an action potential?
A
an electrochemical event created by sudden change in concentration of ions on opposite sides of a neurons cell membrane
20
Q
What occurs during an action potential?
A
the balance of positive and negative ions switches, causing the neuron’s cell membrane to briefly depolaraize
21
Q
What are the steps of an action potential?
A
membrane potential rests at -70mV, stimulus brings the membrane potential to -55mV (threshold), membrane depolarizes, increases to 30mV, repolarizes, hyperpolarizes at -75mV, resets to -70mV
22
Q
What happens while a neuron is at resting potential?
A
no stimulus, resting at -70mV, outside of the neuron is positive and the inside is negative, Na/K pump is open, 3Na out, 2K in
23
Q
What happens when the neuron is at the threshold?
A
nerve impulse is triggered by a mechanical, chemical or electrical impulse, voltage of the membrane changes at the point of stimulation, voltage gated Na channels open, bringing the charge up to -55mV
24
Q
What happens during the depolarization of a neuron?
A
voltage change at the point of stimulation triggers depolarization of the membrane in the next area and so on, continues until 30mV
25
What happens during the repolarization of a neuron?
once the impulse has travelled down the axon, the membrane begins to repolarize, Na gated channels close, K channels open, causing K to diffuse out of the cell, decreasing the membrane
26
What happens during the hyperpolarization of a neuron?
K channels stay open slightly longer than needed bringing the membrane potential back down to -75mV, triggers a reset, Na/K pump reopens, returns to resting
27
What is a refractory period?
a period of time after an action potential when a neuron cannot fire again
28
What is an absolute refractory period?
lasts 1ms, inactive Na channels means the neuron cannot have another action potential
29
What is a relative refractory period?
neuron can have another action potential with a larger stimulus, due to K channels still being open, lasts ~3ms
30
Why do neurons have myelin sheaths?
so the nerve impulses can jump from node to node, with less resistance and a faster impulse
31
What is a synapse?
junction between the synaptic bulb of one neuron and another neuron or effector
32
What happens at a synapse?
nerve signal is transmitted across a tiny gap called the synaptic cleft by neuro-transmitters stored in synaptic vesicles, which are triggered to release via exocytosis by Ca, when the neuro-transmitters diffuse across the cleft, they open Na gated channels, triggering an action potential in the next neuron
33
What are meninges?
layers of membranes that cushion, nourish and protect nerve tissue
34
What is dura mater?
the outermost layer of meninges, made of tough, fibrous, connective tissue
35
What is arachnoid mater?
middle layer of meninges, net-like, with vessels that reabsorb cerebrospinal fluid
36
What is pia mater?
innermost layer of meninges, very thin with blood vessels
37
What is grey matter made of in the spinal cord?
unmyelinated interneurons, cell bodies
38
What is white matter made of in the spinal cord?
bundles of axons, sensory and motor nerves with white myelin sheaths
39
What are dorsal roots?
nerve roots extending from posterior nerves containing sensory neurons whose cell bodies are clumped together in bulb-like regions called dorsal root ganglia
40
What are ventral roots?
nerve roots extending from anterior nerves containing motor neurons whose cell bodies are found in grey matter
41
What are the main regions of the brain?
cerebrum, cerebellum, brain stem
42
What is the cerebrum?
controls complex mental functions, and voluntary responses, divided into left and right hemispheres, and into four lobes
43
What joins the two hemispheres of the cerebrum?
the corpus callosum
44
What are the four lobes of the cerebrum?
frontal, parietal, temporal, and occipital
45
What are the frontal lobes primary functions?
deliberate thoughts, conscious thought, emotions, chewing
46
What are the parietal lobes primary functions?
sensory processing, body orientation, attention, salivation
47
What are the temporal lobes primary functions?
hearing, speech, visual + auditory memory, perceptual judgement
48
What are the occipital lobes primary functions?
vision, object recognition
49
What is the motor cortex?
in the frontal lobe, control + execution of voluntary movements
50
What is the somatosensory cortex?
in the parietal lobe, reception + interpretation of touch
51
What is Broca's area?
in the frontal lobe, generating + articulating oral speech and language
52
What is Wernicke's lobe?
in the temporal lobe, understanding written + spoken speech and language
53
What is the cerebellum?
coordination center for all body movement, communicates with the CNS via nerve tracks called cerebellar peduncles
54
What is the brain stem?
connects cerebrum to spinal cord, controls involuntary functions
55
What is the medulla oblongata?
bottom portion of the brain stem, controls autonomic functions (blood pressure, heart rate, and breathing)
56
What is the pons?
middle bulge of the brain stem
57
What is the midbrain?
top portion of the brain stem, controls autonomic funtions (vision, hearing, motor control, alertness, temp)
58
What is the reticular formation?
nerve fibers found along the brain stem, controls arousal and conscioussness
59
What is the diencephalon?
consists of the thamalus and hypothalamus
60
What is the thalamus?
relays sensory signals to cerebrum and motor signals to spinal cord, regulates conscioussness and sleep
61
What is the hypothalamus? (nervous)
links nervous system to endocrine system via pituitary gland, controls temp and hunger
62
What is the endocrine system?
consists of glands and cells that secrete hormones into the bloodstream
63
How does the body regulate blood glucose levels?
if blood glucose is too high, the pancreas will secrete insulin into the body, and glucose is removed from the blood. if glucose levels are low, the pancreas secretes glucagon, and glucose is released into the blood
64
How does the body regulate the need to sleep?
if you need to sleep, the pineal gland increases melatonin levels. if you need to wake, melatonin levels decrease
65
What are steroid hormones?
lipids, hydrophobic, pass through cell membrane easily, bind with a receptor or protein to form hormone-receptor complex, complex enters nucleus and turns genes on or off
66
What are non-steroid hormones?
proteins, peptides, and amino acids, hydrophilic, binds with receptors on cell membrane forming hormone-receptor complexes outside of the cell, triggers production of a messenger molecule
67
What is the hypothalamus? (endocrine)
produces RH which stimulates the pituitary, affects the pituitary hormones
68
Where is the hypothalamus located?
below the thalamus in the CNS
69
What is the anterior pituitary?
reponds to signals from the hypothalamus, releases HGH (growth of organs and blood glucose), MSH, ACTH (release of hormones by adrenals), FSH (sperm follicle development and estrogen), LH (testosterone, ovulation, and estrogen), prolactin (breast development and milk production)
70
Where is the pituitary located?
at the base of the brain
71
What is the posterior pituitary?
responds to signals from the hypothalamus, releases ADH (increases blood pressure + volume) and oxytocin (contractions of the uterus, milk release by mammary glands)
72
What is the thyroid?
produces thyroxine and thriodothyronine (increase cellular and body metabolism) and calcitonin (decreases blood Ca, increases bone Ca)
73
Where is the thyroid located?
neck, near the larynx
74
What is the parathyroid?
releases parathyroid hormone (PTH), increases blood Ca and decreases bone Ca
75
How does the body regulate blood calcium levels?
if Ca levels rise, the thyroid releases calcitonin which acts on bones and the kidneys to remove Ca from the blood. if Ca levels fall, the parathyroid releases PTH which acts on bones, kidneys, and intestines, to bring more Ca into the blood
76
What is the pancreas?
produces digestion enzymes and hormones, cells that produce hormones are found in the islets of Langerhams, produces glucagon and insuliln to regulate blood glucose levels
77
How does the body regulate blood glucose levels?
if blood glucose is too high, the pancreas will secrete insulin into the body, and glucose is removed from the blood. if glucose levels are low, the pancreas secretes glucagon, and glucose is released into the blood
78
What are the adrenals?
produces epinephrine/norepinephrine, aldosterone, cortisol, and androgens, regulating blood electrolytes, blood glucose levels and anti-inflammatory effects, and it influences sex characteristics
79
What are the ovaries?
produce egg cells, sex hormones, influences development of female sex characteristics
80
What are the testes?
produce sperm cells, sex hormones, influences development of male sex characteristics
81
What is the thymus?
produces and releases hormones into the blood, and promotes the development of immune cells
82
What is the pineal gland?
attached to the thalamus, produces melatonin, involved in regulating the body's day/night cycle
83
What are the four functions of the urinary system?
Filtration, excretion, hormones, homeostasis
84
What is the excretory system?
organs excreting waste, lungs, skin, and urinary system
85
What is a nephron?
functional unit of the kidneys, where blood is filtered and urine is produced
86
How does urine drain out of the kidneys?
urine flows out of the renal pyramids into the minor calyxes, then into major calyxes drain into the renal pelvis which connects to the ureters
87
How does blood move through the kidneys?
Blood enters through the renal artery, and flows around the renal pyramids via interlobular arteries and arcuate arteries which subdivide into afferent arterioles, which enter the nephron
88
What are the steps of the formation of urine?
filtration, reabsorbtion, secretion, excretion
89
What is filtration?
blood flows into the glomerulus capillaries, high blood pressure forces small particles into the bowmans capsule. remaining blood exits via efferent arteriole to enter the peritubular capillaries
90
What is reabsorbtion?
returns useful substances to to the blood, from tubules to pertubular capillaries, substances pumped into capillaries create an osmotic gradient so water diffuses into blood as well
91
What is secretion?
harmful products are pumped out of peritubular capillaries to the renal tubule and/or collecting duct
92
What is excretion?
removal of urine from the body via collecting duct
93
What is the urinary bladder?
elastic muscular sac that sits on the pelvic floor, flexible wall made of 3 layers, 3 openings: two for ureters and one drains to the urethra
94
How do the kidneys regulate blood pressure and volume?
to lower blood pressure, the body produces more urine. to lower the blood pressure the body produces less urine
95
What is renal autoregulation?
control of glomerular capillaries via vasoconstriction/dilation to maintain a steady rate of flow
96
How does ADH regulate blood pressure and volume?
alters blood osmolarity (concentration of solute in the bloodstream) by making the collecting duct permeable to water
97
What is the renin-angiotensin-aldosterone system?
blood pressure is monitored by juxtaglomerular complex, when it detects llow blood pressure it releases renin to the liver which triggers the release of angiotensin I, which is converted to angiotensin II in the lungs, which travels to the adrenal glands and triggers the release of aldosterone, which stimulates the reabsorbtion of Na into the blood, creating an osmotic gradient
98
What is a positive feedback loop?
loop that moves further and further away from homeostasis until the stimulus is removed
99
What is a negative feedback loop?
a loop that brings the system closer to homeostasis
100
What is the autonomic nervous system?
parts of the nervous system that control automatic responses, consists of the parasympathetic and sympathetic nervous systems
101
What are the sympathetic and parasympathetic nervous systems?
Sympathetic: deals with fight or flight
Parasympathetic: rest and digest
102
What is the somatic nervous system?
controls voluntary movement
