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Grade 12 bio > Homeostasis > Flashcards

Homeostasis 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
what are neurotransmitters
chemicals that carry the message/ impulses across these gaps | can have either excititory or inhibitory properties for postsynaptic membrane
26
what are neuromuscular junctions?
synapses between motor neurons and a muscle cell
27
how are signals transmissed across a synapse
- 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
28
what is the spinal cord and what does it do
a column of nerve tissue that extends out of the brain through a canal within the backbone vital communication between brain and peripheral system
29
what does the brain do and what is it
- maintains homeostasis - center for intelligence, conciousness, emotions - can be divided into hindbrain, midbrain and forebrain
30
what are the meninges
3 layers of tough elastic tissue within the skull and spinal colum that directly enclose the brain and spinal cord
31
what does the hindbrain specialize in
coordination and homeostasis
32
what are the 3 main parts of the hindbrain
cerebellum medulla oblogata pons
33
what does the cerebellum do
- unconscious posture coordination, reflexes, body movement, voluntary motor skills - recieves info from specialized sensors (proprioceptors) found within skeletal muscles and joints
34
what does the medulla oblogata do
coordinates reflexes and automatic bodily functions | heart rate, breathing, swallowing, etc
35
what does the pons do
relay centre between neurons on the right and left half of cerebrum and cerebellum
36
what is the midbrain in charge of
processing sensory input relays visual and auditory info between hindbrain and forebrain important role in eye movement and control of skeletal muscles
37
what is the forebrain in charge of
thought, learning and emotions
38
what are the four main parts of the forebrain
thalamus hypothalamus hippocampus cerebrum
39
what does the thalamus do
provides connections between various parts of the brian | relay station essentiallu
40
what does the hypothalamus do
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
what does the cerebrum do
largest part of brain contains centre for intellect, learning, memory, consciousness, language interprets + controls the response to sensory info
42
what is the blood brain barrier
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
what is cerebrospinal fluid
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
what is the cerebral cortex
thin outer covering of grey matter that covers each cerebral hemisphere of the brain responsible for language, memory, personality, thinking, feeling, thoughts
45
what is the corpus callosum
bundle of white matter that joins 2 cerebral hemispheres together sends messages from one hemisphere to another, coordinating actions
46
what is the endocrine system
the collection of different glands that secrete hormones
47
what are hormones
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
what are the two types of hormones
steroid | protein
49
what are steroid hormones
made of cholesterol, non-polar
50
how do steroid hormones works
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
what are protein hormones
made of amino acids, water soluable
52
how do protein hormones work
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
what controls the pituitary gland
the hypothalamus
54
what is a tropic hormone
hormones that target endocrine glands and stimulate them to release other hormoens
55
what is the pituitary gland
the master gland works with hypothalamus to coordinate endocrine and nervous systems produces and stores hormones
56
what are the two lobes of the pituitary gland
anterior | posterior
57
what does the anterior lobe of the pituitary gland do
synthesizes hormones
58
what does the posterior lobe of the pituitary gland do
considered part of the nervous system doesn't produce hormones releases ADH and oxytocin- produced in hypothalamus
59
what is the role of the thyroid gland
metabolic thermostat produces thyroxine (T4) controlled by anterior pituitary gland and TSH (thyroid stimulating hormone)
60
what does T4 do
increases rate at which the body metabolizes fats, proteins, + carbs for energy
61
what does the adrenal medulla do
regulates short term stress response (fight or flight) (activited by hypothalamus) released epineophrine and norepinephrine (increases breath rate, heart rate...)
62
what does the adrenal cortex do
regulates long term stress response stimulates by ACTH from anterior pituitary gland releases cortisol
63
what does cortisol do
promotes breakdown of muscle glycogen and fat into glucose
64
what is the composure and use of the pancreas
contains cells that release digestive enzymes and cells that release hormones hormone producing cells are located in islets of langerhans
65
whata re the two types of hormone producing cells in the pancreas and what do they release
alpha- secretes glucagon | beta- secretes insulen
66
what happens during a blood sugar high
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
what happens after a blood sugar low
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
what makes diabetes occur
when the body cannot control blood sugar levels
69
what are common symptons of diabetes
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
what is type 1 diabetes
born with it early degeneration of beta cells cannot produce insulin- must take it
71
what is type 2 diabetes
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
what is gestational diabetes
temporary condition during pregnancy | body prioritizes giving baby enough insulin over the mother
73
what is GnRH
comes from hypothalamus | stimulates release of FSH and LH from the anterior pituitary
74
what is FSH in the male reproductive system
increases sperm production | comes from pituitary gland
75
what is LH in male reproductive system
promotes testosterone production | comes from pituitary gland
76
what is testosterone
``` produced in testes stimulates speratogensis (production of mature sperm) influences development of secondary sex characteristics (deep voice, facial hair) ```
77
what is an example of a negative feedback loop in the male reproductive system hormonally
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
explain FSH in female reproductive system
stimulates development of follicles | causes estrogen levels to rise
79
explain estrogen in female reproductive system
high levels at midcycle stimulates release of LH after ovulation, inhibits LH and FSH helps endometrium thicken
80
explain LH in female reproductive system
stimulates formation and maintenance of corpus luteum | stimulates ovulation
81
explain progesterone in female reproductive system
inhibits ovulation | stimulates thickening/ maintenance of endometrium
82
what are the four main stages of the female reproductive cycle and their days
flow phase- day 0-5 follicular phase- day 6-13 ovulation phase- day 14 luteal phase- day 15-28
83
what happens during the first 5 days of ovulation
flow phase | shredding of the menstrual cycle
84
what happens during day 6-13 of the menstrual cycle
follicular phase development of follicles in ovaries focciles= groups of cells surrounding an oocyte (devloping egg) mature follicles secrete estrogen
85
what happens during day 14 of the menstrual cycle
ovulation occures | estrogen declines a bit
86
what happens during day 15-28 of the mestrual cycle
``` luteal phase follicle developes into corpus luteum C.L. secretes estrogen and progesterone prepares uterus to recieve a fertilized egg endometrium thickens ```
87
what are the two types of sex hormones for females and how are they different
GnRN- released by hypothalamus (tropic hormone) | ovarian hormones- released by the ovaries directly

Grade 12 bio (7 decks)

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