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biology > Homeostasis > Flashcards

Homeostasis Flashcards

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AP® Biology flashcards
1
Q

What is the internal environment

A

Composed of extracellular fluid which has interstitial fluid and plasma
-NOT intracellular fluid

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2
Q

In order to survive all organisms must

A
  1. take in nutrients, process, and dispose them
  2. they must respond to change in environment
  3. produce molecules like fat, carbs, proteins, for cellular function
  4. protect body from injury and fight infection
  5. reproduce
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3
Q

Most important systems for maintaining homeostasis

A

Nervous and endocrine

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4
Q

Monitor organ systems

A

organ systems that send signals when body’s organ function goes out of normal range

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5
Q

Negative feedback

A

Primary mechanism of homeostasis, cancels/counteracts the stimulus

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6
Q

Explain the pathway of homeostatic mechanism

A

Stimulus -> sensory/receptor -> sensory pathway -> afferent neurons -> integrator/CNS/interneurons -> motor pathway/efferent neurons -> effectors

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7
Q

What is the set point

A

Optimal value of a system, if it goes beyond this value your integrators activates effectors

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8
Q

What happens when the body is cold

A

Stimulus: being cold
Thermoreceptors detect the temperature change
Send through the sensory pathway through afferent neurons
Send to the CNS with interneurons which process info
Send to the efferent/motor pathway
Efferent neurons send signals to your effectors

Effector response:

Your blood vessels will constrict so thermal energy isn’t lost
You will also shiver which generates body heat

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9
Q

What happens when the body is hot

A

Stimulus: increase in temperature
Thermoreceptors detect increase in temperature and then send to afferent neurons in your sensory pathway to the interneurons in the central nervous system.
Central nervous system processes information, compares to a set point and then sends out signal
Signal is sent through efferent neurons in motor pathway

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10
Q

What happens when theres a fever in your body?

A

Your body’s set point increases in response to the virus to fight off the infection and return to normal

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11
Q

Positive feedback + examples

A

An increase in the environmental stimulus
Does not maintain homeostasis
-flight or fight
-childbirth (releases oxytocin which stimulates contractions)

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12
Q

What kind of receptors detect temperature change?

A

Thermoreceptors in your skin and organs which compare to your set point

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13
Q

Explain flight or fight and oxytocin as positive feedback

A

When you get scared, your body releases hormone epinephrine and norephrine which increases when more is secreted
Oxytocin is secreted in response to childbirth

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14
Q

Which part of the brain controls temperature?

A

The hypothalamus

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15
Q

What is osmoregulation

A

The regulation of osmotic pressure which is the difference in water/solute concentration across a membrane

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16
Q

What are nephrons

A

The functional unit of the excretory system that regulate water balance and urine output

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17
Q

What kind of animals are able to secrete ammonia?

A

Animals that have high levels of water inside of their body like freshwater fish are able to dilute the ammonia and keep it safely in their bodies

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18
Q

Blood flow in kidneys

A

Renal artery > afferent arteriole > glomerlus > efferent arteriole > pertibular capillaries > renal vein

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19
Q

Fluid flow in the kidneys

A

Bowman’s capsule > proximal convulated tubule > descending loop of henle > ascending loop of henle > distal convulated tubule > collecting ducts > renal pelvis > ureter > urinary bladder > urethra

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20
Q

Explain the whole entire process of filtration

A
  1. Blood flows in from the renal artery into the afferent arteriole into the glomerulus and filters out glucose, ions, urea, a.a, small nutrients
    keeps the large proteins, blood cells, and platelets

The fluid that is filtered into the glomerulus is called the filtrate

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21
Q

Explain the process of reabsoprtion

A

The point of reabsorption is to reabsorb most nutrients as well as water into the extracellular fluid

1.Active transport pumps pump out Na+ K+ and Cl- as well as a.a, glucose, from the filtrate and then since the solute concentration is so high outside water flows out and follows it (passive)

Remaining nutrients and water are reabsorbed by proximal convoluted tubule and taken into the peritubular capillaries to send back to blood

  1. Then the remaining fluid flow into the descending loop of henle where most water is reabsorbed and becomes very hyperosmotic (due to high solute)
  2. Goes up the ascending loop of henle where more ions are reabsorbed and its passive at first due to the high solute concentration but active as it heads up
  3. Distal convulated tubule- Then remaning solutes like Na+ Cl- HCO3- are moved out making it hypoisomotic and then water follows it out
  4. In the collecting ducts, urea and waste enter through the ducts and its permeable to water but not salt ions therefore the urine becomes very concentrated
  5. Goes out through the renal pelvis for excretion
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22
Q

Secretion

A

Secretion is secreted waste into the nephron to remove it
-occurs in the convoluted tubules and collecting ducts
-primarily hydrogen ions are secreted back into the nephron to control acidity

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23
Q

What happens when the aciditiy of interstitial fluid gets too high?

A

H+ ions are secreted into the nephrons and they are released in urine to control pH

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24
Q

A patient did not 100% reabsorb their glucose, and their urine was detected with high levels of sugar. Why is this?

A

This person is diabetic, they do not have insulin to lower their levels of glucose therefore they have high levels of glucose in their blood and not all of it can be reabsorbed back

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25
Q

Why are there high levels of urine in a diabetic person?

A

They have a lot of solute in their filtrate which means theres less water so water is going to move in to restore that balance and its gonna cause more urine.

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26
Q

What is ADH what does it do?

A

Antidieuretic hormone is released by the posterior pituriary and causes kidneys to increase their water reabsorption
- the hypothalamus detects high solute concentration in the blood and sends a signal to the posterior pituitary to drive water out of filtrate
-when ADH reaches the kidneys the convoluted tubules and the collecting ducts to become more permeable to water and returns water to blood

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27
Q

Aldosterone

A

A hormone released when blood pressure is low (which means theres low water), and increases Na+ reabsoption
-when Na+ is reabsorbed, water follows it out and blood pressure increases

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28
Q

What happens when you sweat? What happens to urine output?

A

When you sweat you lose water in your interstitial fluid, which means that theres going to be higher solute concentration in the blood. This is going to make more water flow out of the nephrons in order to balance water so urine output will decrease.

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29
Q

Protein hormones

A

-made from amino acids
-they are hydrophilic
-bind to receptors on the membrane and signal a cascade of reactions
-

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30
Q

Steroid hormone

A

-made from cholesterol
-they diffuse through the membrane and attach to receptors inside of the cell
-the receptor-hormone complex then attaches onto a segment of gene

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31
Q

What kinds of hormones does the hypothalamus release?

A

Stimulating/inhibting hormones

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32
Q

What is the hypothalamus controlled by

A

Other inputs from neurons from the nervous system, your neurons take the signal that your body needs something and sends it to the hypothalamus

33
Q

What is the master gland

A

The pituitary gland

34
Q

Growth Hormone

A

Stimulates protein synthesis, bone growth in children, cell division
-works with insulin like growth factor
-maintain blood and glucose levels between meals

35
Q

Thyroid releasing hormone

A

Stimulates TSH in the anterior pituitary to release

36
Q

Thyroid stimulating hormone

A

Stimulates production of calcitonin and thyroxine

37
Q

Adrenocorticotropic release hormone (ACTH)

A

Stimulates the release of cortisol in the adrenal cortex

38
Q

Follcile stimulating hormone

A

Stimualtes the release of eggs and folliciles in female and spermatogensis in male

39
Q

Lutenizing hormone

A

Controls the male sex hormone and regulates menstrual cycle in females

40
Q

What two hormones do thyroid release

A

Calcitonin and thyroxine

41
Q

Why is iodine so important in the diet?

A

Iodine is important because it is need to produce thyroxine and thyroxine sends negative feedback to the pituitary so if there’s not enough thyroxine, it’s going to form a goiter due to inability to send negative feedback

42
Q

What hormones do parathyroid glands produce?

A

Parathyroid hormone which also releases calcitriol

43
Q

Calcitriol

A

hormone released by the parathyroid hormone and is active form of vitamin D, it increases absorption of Ca2+ from food

44
Q

Thyroxine

A

Thyroid hormone released by the thyroid glands which assist in metabolism, development, maturation and interacts with growth hormone

45
Q

Calitnonin

A

Released by the thyroid and lowers Ca2+ levels in blood

46
Q

Parathyroid hormone

A

Increases Ca2+ levels in blood by taking calcium out of bones - can cause osteoporosis

47
Q

Adrenal medulla secretes

A

Secretes epinephrine and norephrine

48
Q

What is epinephrine and norephrine function

A

They increase heart rate, prepare body for stress, dialate airways, increases breakdown of glucose and fats for fuel

49
Q

Adrenal cortex secretes ____ which…

A

Secretes cortisol which increases blood glucose levels and decreases glucose uptake by body cells
promotes breakdown of fatty acids and proteins

50
Q

Two hormones that control blood sugar

A

Insulin and glucagon, released by pancreas by islets of langerhams
Insulin - beta ceclls
Glucagon - alpha cells

51
Q

What does insulin do

A

-lowers blood sugar
glucose -> glycogen
fatty acids -> fats
amino acids -> proteins

52
Q

What does glucagon do

A

-increases blood sugar
-usually in response to fasting
glycogen -> glucose
fats -> fatty acids
proteins -> a.a

53
Q

Diabetes Melitus

A

A person who cannot produce insulin and has consistenly high blood glucose levels
-damaged tissue
-frequent urination
-thirsty
-increased appetite

54
Q

What is GnRH

A

the neurohormone that stimulates LH and FSH

55
Q

What does LH stimulat

A

male sex hormones and female menstrual cycle hormones

56
Q

What does FSH stimulate

A

stimulates egg and sperm production

57
Q

Explain the pathway of GnRH in males

A

GnRH -> LH and FSH from anterior pituitary gland
LH stimulates leydig cells in testes to produce testosterone
FSH stimulates sertoli cells in testes to begin spermatogensis

When testosterone levels are high… it inhibits GnRH and also releases inhibin which inhibits FSH

58
Q

Explain the pathway of GnRH in females

A

GnRH -> LH and FSH from anterior pituitary
FSH -> creates growing follicile -> follicile releases estrogen
LH -> stimulates growth of the corpus luteum > corpus leteum rleeases progesterone and some estrogen

59
Q

What does estrogen do

A

Stimulates development of secondary sexual characteristics

60
Q

What does progesterone do

A

Stimulates development of uteral lining, inhibits cramps and inhibits GnRH which inhbits LH and FSH also releases inhibin

61
Q

Explain the menstrual cycle

A

GnRN -> LH and FSH
FSH creates the follicile and egg and the follicile releases estrogen
The estrogen in small amounts inhibits FSH and stimulates LH (which produces some estrogen)
The sudden peak in LH stimulates the formation of corpus leutum which releases progesterone and also releasing of the egg
Progesterone stimulates uteral lining, inhibits cramps, inhibits the GnRH and also releases inhibin
-fertilization does not occur then the corpus leteum breaks down and then uterus is shed and repeat cycle

62
Q

Neuron

A

specialized nerve cell that carries electrical signals

63
Q

Afferent neurons

A

Take stimuli from receptors and send it to the interneurons in CNS

64
Q

Explain the whole subdivision of the nervous system

A

Draw out the chart

65
Q

Somatic vs automic

A

somatic = voluntary -> skeletal muscles, shivers
autonomic = involuntary

66
Q

Sympathetic vs parasympathetic

A

Sympathetic - flight or fight
Parasympathetic - rest relax

both affect smooth muscles and glands

67
Q

Explain examples of parasympathetic vs sympathetic

A

parasympathetic =
-constrict pupils, salivation, heart rate lowers, relax airways, digestive activity, stimulates gallbladder
-contracts bladder
-relaxes rectum

sympathetic
-dilates pupils, inhibits salivation, increases heart rate, stimulates glucose release, secretion of norephrine by adrenal medulla

68
Q

What is a reflex arc

A

A neural circuit that does not require coordination from the brain but uses the spinal chord instead

69
Q

Synapse

A

site where two neurons make connections or a neuron with an effector

70
Q

Axon terminal side is the ________
dendrite side is the _________-

A

Axon terminal - the presynaptic cell
dendrite - post synaptic cell

71
Q

Conduction across a chemical synapse explain

A

normally Ca2+ channel proteins actively shuttle Ca2+ out of the axon to keep the concentration high outside and low inside

Action potentials travel along an axon and then once it reaches the axon terminals, and this causes Ca2+ gates in axon terminal to open Ca2+ channels (passive) and bring them into the cytosol
The rise in Ca2+ triggers a protein to release which makes vesicles fuse with the plasma membrane
This release neurotransmitters into the synaptic cleft by exocytosis
Neurotransmitter molecules diffuse across the cleft and bind to the receptor molecules in the membrane of the postsynaptic neuron
The binding of these neurotransmitters opens ion channels which allows ions to flow into dendrite/cell body of postsynaptic neuron

If the post synaptic neuron becomes depolarized by the ions moving in to the point of threshold, it generates another action potential

72
Q

What is the charge of teh axon at resting potential?

A

negative inside + outside
Na/K pump
3 Na out
2 K in

73
Q

What voltage is resting potential

A

-70mV

74
Q

Explain an action potential

A

Stimulus occurs: spider on hand
Phase 1: the stimulus brings incoming + ions and raises the membrane potential until it reaches the threshold potential and then depolarizes

Phase 2: Above the threshold potential, Na+ channels continue to open and positive ions flow into the axon and then it reaches a maximum peak

Phase 3: The action potential reaches it peak at around 30mV and here sodium channels close and K+ channels reopen

Phase 4: The K+ ions flow out of the ion and keep flowing out and repolarizes the axon

Phase 5: The axon briefly hyperpolarizes because k+ channels are slow to close

Phase 6: Membrane potential stabilizes at resting value and ready for a new action potnetial

Phase 4:

75
Q

All or nothing principle

A

Once the stimulus passes the threshold potential it will generate an action potential no matter the strength of stimulus

76
Q

Refractory period

A

Begins at the peak of the action potential and makes it hard for another action potetial to be generated until the current one has restabilized at resting potnetial
-ensures one way movement

77
Q

Why do myelinated axons increases the speed of electrical impulses?

A

They insulate parts of the axon and the nodes of ranvier are very concentrated in ion channels so they can jump really fast

78
Q

Electrical synapse

A

Electrical currents travel across and travel through gap junctions

79
Q

Chemical vs electrical synapse

A

Chemical is slower, but more precise and selective

Electrical is faster but its a lot harder to control since the electric currents activate consecutively

biology (8 decks)

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