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Grade 12 bio > Homeostasis > Flashcards

Homeostasis Flashcards

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Biology 101 flashcards
1
Q

what is the definition of homeostasis

A

the tendency of the body to maintain a relatively constant internal environment

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2
Q

what are feedback systems

A

a cycle of events in which a variable (body temp, glucose levels, blood pH) is monitored, assessed and adjusted

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3
Q

what are the three components of feedback systems and their roles

A
  1. sensor- detects a change in internal environment
  2. control centre- sets range of values within which a variable should remain
  3. effector- receives signal form control centre and creates a change to the internal variable
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4
Q

what is a negative feedback system

A
  • the output of a system reverses a change in a variable, bringing it back to within normal range
  • imagine a seesaw- can always add more or less to one side to balance it out
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5
Q

what is a positive feedback system

A

The output of a system strengthens or increases a change in a variable

  • tends to be involved when there is a definitive cut off point
  • being in labour/ blood clotting
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6
Q

are positive or negative feedback systems more common?

A

negative

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7
Q

what is a neuron and how are they composed

A

a nerve cell, made up of a nucleus, cell body, dendrites, and axons

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8
Q

what is a nerve

A

message pathway of the nervous system

made up of neuron cells grouped into bundles and surrounded by protective connective tissue

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9
Q

what is a glial cell

A

the supportive cell of the nervous system

nourishes neurons, removes the waste, defends against infection, provides frames

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10
Q

explain electrochemical impulses and what they are

A

nerve impulses are an electrochemical message

theyre related to the movement of charges ions (NA+ and K+) across the membrane of the axon

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11
Q

what is the resting potential and which value does it have

A

it is the potentiall difference across the membrane in a resting neuron
-70mV
is negative because more K+ is diffusing out than Na+ diffusing in
we say it is polarized

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12
Q

how do neurons get stimulated

A

excited by their environment, brain or a neurotransmitter

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13
Q

what is the threshold potential and which value does it have

A

-50mV
the minimum level of stimulus that will result in a response
all or nothing response where you either feel it or you don’t
if the stimulus is above the the threshold level, the impulse will be sent
the more intense thee stimulus is, the more times the impulse will send

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14
Q

describe the action potential and its value

A

+40mV

the membrane becomes depolarized after reaching threshold potential and shooting up

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15
Q

what are the three types of neurons

A

multipolar, bipolar, unipolar

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16
Q

describe the multipolar neuron characteristics

A

several dendrites
single axon
found in brain and spinal cord

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17
Q

describe the characteristics of bipolar neurons

A

single main dendrite
single axon
found in inner ear, retina of eye, and olfactory area of brain

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18
Q

describe the characteristics of unipolar neurons

A

single process that extends from cell body
dendrite + axon are fused
found in peripheral nervous system

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19
Q

explain how nerve impulses are conducted

A

sensory input
integration
motor output

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20
Q

explain the sensory input

A

taken in by sensory receptors in skin
receive stimuli and form a nerve impulse
transmit impulses from sensory receptors to CNS

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21
Q

explain integration

A

interneurons are found entirely within the CNS
act as a link between sensory and motor neurons
process and integrate incoming sensory info and relay motor

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22
Q

explain motor output

A

motor neurons transmit info from the CNS to effectors

effectors include muscles, glands, organs

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23
Q

explain how mylinated nerve impulses work

A
  • nerve impulses jump over the myelin sheath rather than traveling through it- shorter distance
  • nerve impulses consist of a series of action potentials
  • nodes of ranvier contain many voltage gated sodium channels, which cannot work through the myelin sheath as sodium ions cannot travel through it
  • so, the nerve impulses just jump over the myelinated areas
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24
Q

what are synapses

A

connection between 2 neurons or between a neuron and an effector

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25
Q

what are neurotransmitters

A

chemicals that carry the message/ impulses across these gaps

can have either excititory or inhibitory properties for postsynaptic membrane

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26
Q

what are neuromuscular junctions?

A

synapses between motor neurons and a muscle cell

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27
Q

how are signals transmissed across a synapse

A
  • impulse travels to the synapse terminal
  • synaptic vesicles move towards and fuse w the postsynaptic membrane
  • neurotransmitters are released into the synaptic cleft
  • neurotransmitters bind to receptor proteins and affect the postsynaptic neuron
  • enzymes will break up the neurotransmitter, which will be reabsorbed
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28
Q

what is the spinal cord and what does it do

A

a column of nerve tissue that extends out of the brain through a canal within the backbone
vital communication between brain and peripheral system

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29
Q

what does the brain do and what is it

A
  • maintains homeostasis
  • center for intelligence, conciousness, emotions
  • can be divided into hindbrain, midbrain and forebrain
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30
Q

what are the meninges

A

3 layers of tough elastic tissue within the skull and spinal colum that directly enclose the brain and spinal cord

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31
Q

what does the hindbrain specialize in

A

coordination and homeostasis

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32
Q

what are the 3 main parts of the hindbrain

A

cerebellum
medulla oblogata
pons

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33
Q

what does the cerebellum do

A
  • unconscious posture coordination, reflexes, body movement, voluntary motor skills
  • recieves info from specialized sensors (proprioceptors) found within skeletal muscles and joints
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34
Q

what does the medulla oblogata do

A

coordinates reflexes and automatic bodily functions

heart rate, breathing, swallowing, etc

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35
Q

what does the pons do

A

relay centre between neurons on the right and left half of cerebrum and cerebellum

36
Q

what is the midbrain in charge of

A

processing sensory input
relays visual and auditory info between hindbrain and forebrain
important role in eye movement and control of skeletal muscles

37
Q

what is the forebrain in charge of

A

thought, learning and emotions

38
Q

what are the four main parts of the forebrain

A

thalamus
hypothalamus
hippocampus
cerebrum

39
Q

what does the thalamus do

A

provides connections between various parts of the brian

relay station essentiallu

40
Q

what does the hypothalamus do

A

regulates the body’s internal environment and behaviour
controls blood pressire, heart rate, body temp, basic drive, emotions
major link between nervous and endocrine system
coordinates pituitary gland actions or producing and regulating hormones

41
Q

what does the cerebrum do

A

largest part of brain
contains centre for intellect, learning, memory, consciousness, language
interprets + controls the response to sensory info

42
Q

what is the blood brain barrier

A

protective barrier made up of glial cells and blood vessels that seperates the blood from the CNS
selectively permeable; controls the entrance of substances into the brain from the blood (glucose, oxygen, nutrients…)

43
Q

what is cerebrospinal fluid

A

liquid derived from blood plasma
found in brain ventricles, central canal of spinal cord, meninges
transmits hormones, WBC, and nutrients across BBB to brain cells and spinal cord
shock absorber to cushion brain
replaced about 4 times daily

44
Q

what is the cerebral cortex

A

thin outer covering of grey matter that covers each cerebral hemisphere of the brain
responsible for language, memory, personality, thinking, feeling, thoughts

45
Q

what is the corpus callosum

A

bundle of white matter that joins 2 cerebral hemispheres together
sends messages from one hemisphere to another, coordinating actions

46
Q

what is the endocrine system

A

the collection of different glands that secrete hormones

47
Q

what are hormones

A

chemical regulators/ messengers
produced in one part of the body but affects cells in another
only small amounts are needed for a large effect

48
Q

what are the two types of hormones

A

steroid

protein

49
Q

what are steroid hormones

A

made of cholesterol, non-polar

50
Q

how do steroid hormones works

A

easily diffuse through phospholipid bilayer
binds to a receptor protein within nucleus
this activates transcription of a gene
mRNA is synthesized and protein synthesis occurs

51
Q

what are protein hormones

A

made of amino acids, water soluable

52
Q

how do protein hormones work

A

cannot diffuse through bilayer, so they bind to receptor protein on surface
this trigger formation of cAMP from ATP
cAMP is a secondary messenger which activates an enzyme cascade
once hormone messages have been delivered, enzymes disassociate and stop

53
Q

what controls the pituitary gland

A

the hypothalamus

54
Q

what is a tropic hormone

A

hormones that target endocrine glands and stimulate them to release other hormoens

55
Q

what is the pituitary gland

A

the master gland
works with hypothalamus to coordinate endocrine and nervous systems
produces and stores hormones

56
Q

what are the two lobes of the pituitary gland

A

anterior

posterior

57
Q

what does the anterior lobe of the pituitary gland do

A

synthesizes hormones

58
Q

what does the posterior lobe of the pituitary gland do

A

considered part of the nervous system
doesn’t produce hormones
releases ADH and oxytocin- produced in hypothalamus

59
Q

what is the role of the thyroid gland

A

metabolic thermostat
produces thyroxine (T4)
controlled by anterior pituitary gland and TSH (thyroid stimulating hormone)

60
Q

what does T4 do

A

increases rate at which the body metabolizes fats, proteins, + carbs for energy

61
Q

what does the adrenal medulla do

A

regulates short term stress response (fight or flight) (activited by hypothalamus)
released epineophrine and norepinephrine (increases breath rate, heart rate…)

62
Q

what does the adrenal cortex do

A

regulates long term stress response
stimulates by ACTH from anterior pituitary gland
releases cortisol

63
Q

what does cortisol do

A

promotes breakdown of muscle glycogen and fat into glucose

64
Q

what is the composure and use of the pancreas

A

contains cells that release digestive enzymes and cells that release hormones
hormone producing cells are located in islets of langerhans

65
Q

whata re the two types of hormone producing cells in the pancreas and what do they release

A

alpha- secretes glucagon

beta- secretes insulen

66
Q

what happens during a blood sugar high

A

occurs after a meal
beta cells release insulin into blood
insulin makes cells of muscles, live + organs to absorb more glucose
liver converts glucose to glycogen (stored energy source)
blood glucose levels decrease

67
Q

what happens after a blood sugar low

A

happens after fasting
alpha cells release glycogen into blood
liver converts glycogen back into glucose and releases it into blood
blood glucose levels increase

68
Q

what makes diabetes occur

A

when the body cannot control blood sugar levels

69
Q

what are common symptons of diabetes

A

hyperlycemia (high blood sugar)
lots of water loss (thirsty)
kidneys cannot absorb all the glucose (high amounts in urine)
cells impermeable to glucose (low energy)
acetone on breath (product of fat metabolism)

70
Q

what is type 1 diabetes

A

born with it
early degeneration of beta cells
cannot produce insulin- must take it

71
Q

what is type 2 diabetes

A

decreased insulin production or ineffective use of insulin
generally diagnosed in adulthood but more kids are getting it
can often be controlled by diet and exercise

72
Q

what is gestational diabetes

A

temporary condition during pregnancy

body prioritizes giving baby enough insulin over the mother

73
Q

what is GnRH

A

comes from hypothalamus

stimulates release of FSH and LH from the anterior pituitary

74
Q

what is FSH in the male reproductive system

A

increases sperm production

comes from pituitary gland

75
Q

what is LH in male reproductive system

A

promotes testosterone production

comes from pituitary gland

76
Q

what is testosterone

A 
produced in testes
stimulates speratogensis (production of mature sperm)
influences development of secondary sex characteristics (deep voice, facial hair)
77
Q

what is an example of a negative feedback loop in the male reproductive system hormonally

A

high LH leads to high T
high T inhibits GnRH and thus LH

OR

FSH causes sertoli cells to help sperm mature
mature sperm cause sertoli cells to release inhibin which inhibits GnRN thus FSH

78
Q

explain FSH in female reproductive system

A

stimulates development of follicles

causes estrogen levels to rise

79
Q

explain estrogen in female reproductive system

A

high levels at midcycle stimulates release of LH
after ovulation, inhibits LH and FSH
helps endometrium thicken

80
Q

explain LH in female reproductive system

A

stimulates formation and maintenance of corpus luteum

stimulates ovulation

81
Q

explain progesterone in female reproductive system

A

inhibits ovulation

stimulates thickening/ maintenance of endometrium

82
Q

what are the four main stages of the female reproductive cycle and their days

A

flow phase- day 0-5
follicular phase- day 6-13
ovulation phase- day 14
luteal phase- day 15-28

83
Q

what happens during the first 5 days of ovulation

A

flow phase

shredding of the menstrual cycle

84
Q

what happens during day 6-13 of the menstrual cycle

A

follicular phase
development of follicles in ovaries
focciles= groups of cells surrounding an oocyte (devloping egg)
mature follicles secrete estrogen

85
Q

what happens during day 14 of the menstrual cycle

A

ovulation occures

estrogen declines a bit

86
Q

what happens during day 15-28 of the mestrual cycle

A 
luteal phase
follicle developes into corpus luteum
C.L. secretes estrogen and progesterone
prepares uterus to recieve a fertilized egg
endometrium thickens
87
Q

what are the two types of sex hormones for females and how are they different

A

GnRN- released by hypothalamus (tropic hormone)

ovarian hormones- released by the ovaries directly

Grade 12 bio (7 decks)

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