Homeostasis Flashcards
(97 cards)
1
Q
define homeostasis
A
- process where constant internal environment is maintained despite the changes in the external environment, and constant balance is achieved through monitored adjustments
2
Q
what are the components of a homeostatic control system?
A
- monitor that detects change in variable
- coordinating center that receives message from monitor and sends resposne
3.regulator that carries out response initiated by the coordinating center
3
Q
what is the hypothalamus?
A
- part of the brain that serves as the coordinating center that recieves message from the monitors to initiate a hormonal or nervous response
4
Q
explain dynamic equilibrium
A
- another term for homeostasis that refers to the balance in our bodies that can be maintained within an acceptable change
5
Q
explain a negative feedback loop
A
- change in conditions triggers a response that reverses that change
6
Q
explain a positive feedback loop
A
- change in conditions that trigger a response that reinforces that change
7
Q
what is the function of the endrocrine system?
A
- maintain homeostasis by releasing hormones from glands in the body
8
Q
define glands
A
- secrete hormones and other substances into the bloodstream as they do not have ducts
9
Q
define hormones
A
- affect a broad range of cells and work slowly but are long lasting
- chemicals produced at the source and communicates regulatory messages within the body
10
Q
what are the two types of hormones and explain
A
1.peptide hormones that require a receptor as they are not membrane permeable. Will bind to receptor and trigger cascade of reactions in cell
- steroid hormones that can pass through the cell membrane without a receptor and bind to one in the nucleus or cytoplasm and activate specific genes
11
Q
explain the master gland of the hypothalamus
A
- connects endocrine system to nervous system and receives signals from body and initiates release of hormones
12
Q
explain the master gland of the pituitary gland
A
- secretes hormones made in the hypothalamus and stimulates other glands to release hormones
13
Q
what are the two regions of the pituitary gland
A
- posterior region
- anterior region
14
Q
what hormones does the posterior region release?
A
- ADH to regulate osmoregularity in kidneys
-oxytocin to act on muscles in uterus during labour and causes mammary glands to release milk
15
Q
what hormones does the anterior region release?
A
- TSH that stimulates the thyroid
- ACTH that stimulates the adrenal glands
- FSH that acts on the gonads (ovaries and testes)
- LH that acts on the gonads (sex cells)
- MSH to stimulate release of melanin
- growth hormone that act on the muscles
- prolactin in mammary glands
16
Q
what are tropic hormones?
A
- hormones that stimulate other glands to release hormones
17
Q
name the hormones involved in the regulation of blood sugar
A
- insulin decreasing blood sugar
2.glucagon increasing blood sugar - epinephrine increasing blood sugar and mobilizing carbs
- norepinephrine increasing blood sugar turning glycogen into glucose
- cortisol increases blood sugar under stress so sugars are available for metabolism
18
Q
explain how insulin regulates blood sugar
A
- comes from beta cells in islets of langerhans and pancreas
- target liver muscle and other body cells to increase permeability to glucose
- in liver glucose becomes glycogen
- reduces blood sugar
19
Q
explain how glucagon regulates blood sugar
A
- comes from alpha cells in islets of langerhans and pancreas
- target liver to convert glycogen to glucose
- increases blood sugar
20
Q
what kind of feedback loop is thyroid involved in?
A
negative
21
Q
explain how the thyroid gland regulates metabolism
A
- metabolic rate decreases, and receptors in hypothalamus recognize this and release TRH which is thyroid releasing hormone
- TRH travels to anterior pituitary to release TSH
- TSH travels to thyroid gland to release thyroxine that travels to body cells to stimulate increase in
cellular respiration - increased thyroxine signals hypothalamus to stop making TRH
22
Q
what is goiters?
A
- when iodine deficient thyroxine levels drop so TRH keeps stimulating release of TSH that overstimulate thyroids resulting in an enlargement of the gland
23
Q
what is the parathyroid?
A
- 4 small glands that release PTH that regulates blood calcium level
24
Q
explain the growth hormone
A
- comes from the anterior pituitary and targets mostly cartilage and bone cells
- increases the number and size of soft tissue and bone cells by increasing amino acid uptake by stimulating ribosomes for protein synthesis
- stimulates liver to release IGFs that stimulate cell division and promoting the elongation of skeletons and long bones and increasing the breakdown of fats for energy
25
What is acromegaly?
- when a person is done growing but hgH is still largely produced and the bones become wide, ribs thick, face wide and hands and feet enlarged
26
explain the flight or fight response
- hypothalamus senses danger
- can activate the sympathetic nervous system which will activate the glands and smooth muscles, but also activates adrenal medulla to release epinephrine and norepinephrine into the blood
- hypothalamus can also activate adrenal cortex by releasing CRF that stimulates pituitary into releasing ACTH targetting adrenal cortex to release 30+ hormones
27
what stress is the adrenal medulla responsible for?
short term stress
28
what does norepinephrine and epinephrine target?
blood vessels,eyes, livers, muscles,heart, lungs
29
what happens when epinephrine and norepinephrine are released?
- liver and muscles break down glycogen and release fatty acids from fat cells
- heart rate and stroke volume increase
- blood vessels constrict and dilate for more oxygen and nutrient delivery to essential hormones
- retinas dilate for more visual information
-bronchioles dilate so respiration rate increases
30
what stress is the adrenal cortex responsible for?
- long term stress
31
what are glucocorticoids?
- released by adrenal cortex and increase blood sugar
32
what are mineralcorticoids?
- released by adrenal cortex to increase blood pressure
33
explain how cortisol regulates stress
- increases breakdown of muscle protein into glucose to be released into blood stream
-reduces its uptake in certain cells
- hypothalamus senses danger and releases CRF that stimulates pituitary to release ACTH that causes adrenal cortex to release cortisol
- negative feedback loop as increased cortisol supresses ACTH to stop release of cortisol
34
why is being under constant stress harmful?
- large levels of cortisol
- impaired thinking, heart muscle damage, high blood pressure, risk of infection
35
explain what aldesterone does
- plays a role in water and salt balance by stimulating kidneys to increase salt absorption in blood, increasing solute so the water is drawn to the blood via osmosis to increase blood pressure
36
name the male reproductive hormones:
1. testosterone: stimulates spermaotgenesis and secondary male sexual characteristics and sex drive
2. FSH stimulates sperm production by acting on sperm producing cells
3. LH stimulates production of testosterone
4. androsterone which is the less potent testosterone
5. GnRH that releases FSH and LH from pituitary
37
explain how the male reproductive hormones work:
- hypothalamus reeases gnRH to stimulate the anterior pituitary into releasing FSH and LH that target the testes
- FSH stimulates the sertoli cells to influence sperm production
- LH acts on the interstitial cells to release testosterone that also influences sperm production
- testosterone and ihibin both inhibit the hypothalamus and anterior pituitary
38
what are steroids?
- synthetic derivatves of testosterone that promote muscle growth and can be abused by body builders and atheletes but can be legally prescribed to males with low testosterone and to patients with HIV
39
what happens when one takes anabolic steroids?
- men can develop breasts and reduce their own sexual characteristics
-same for women
- aggressive behaviour and mood swings
40
What are the female reproductive hormones?
- estrogen: released by follicle cells that increase the thickness of the uterine lining and responsible for secondary female sexual charactertistics
- FSH: stimulates follicle production in the ovaries and inhibited by high levels of estrogen
- LH promotes ovulation and formation of corpus luteum and is stimulates by high levels of estrogen at first, then inhibited by both it and progesterone
- progesterone: produces by the ovaries and maintain the unterine lining during pregnancy
-GnRH releasing FSH and LH from the pituitary gland at puberty
41
explain the ovulation cycle
1. primordial follicle becomes a primary follicle with the primary ovum
2. egg develops and in mature follicle a secondary ovum develops
3. follicle ruptures at ovulation and the ovum is liberated
4. the follicle becomes a corpus luteum that becomes the corpus albicans as the ovum travels to the uterus
42
during the ovulation period, what hormones are high at what levels?
- follilcular phase: FSH and LH are low, estrogen is mid and progesterone is low
- at ovulation: estrogen and LH are high
- post ovulation: progesterone is high
43
define the nervous system
- a communication system made of many nerve cells and looks after memory, learning, language, motor control, emotions, locomotion and more
44
what are the two "mini" nervous systems?
1. central nervous system
2. peripheral nervous system
45
define the central nervous system
- consists of the nerves in the brain and spinal cord and is the coordinating center for incoming and outgoing information
46
define the peripheral nervous system
- consists of all the nerves that carry information between the organs and the CNS,including the somatic nervous system and autonomic nervous system
47
define the somatic nervous system
- controls skeletal muscles, bones and skin
- voluntary
- sensory nerves
48
define the autonomic nervous system
- involuntary
- controls the internal organs
- sympathetic and parasympathetic nervous system
49
what does the sympathetic nervous system do?
- prepare body for stress
50
what does the parasympathetic nervous system do?
- return body to normal levels after stress
51
what are the two types of nerve cells
- glial cells
- neurons
52
explain glial cells
- non conducting
- important for structural support and the metabolism of nerve cells
53
explain neurons
- functional units of the nervous system
- conduct nerve impulses
- three types: sensory, inter, and motor
54
describe the three types of neurons
1. Sensory: afferent neurons that sense and relay information and stimuli from the environment to the CNS for processing and is located in clusters (ganglia) outside the CNS
2. Interneurons or association neurons link neurons in the body and are mostly found throughout the brain and spinal cord; interprets sensory information and connects the neurons to outgoing motor neurons
3. motor : efferent neurons that relay information to the effectors to produce a response
55
what are nerve cells made up of?
- cell bodies with a nucleus
- dendrites (branches that receive information from sensory receptors/other nerve cells and conduct impulse TOWARD cell body)
- axons (extension of cytoplasm that projects nerve impulses from cell body to other neurons or effectors)
- mylein sheaths (insulate axons)
- Schwann cells (special glial cells that form mylein sheaths)
- nodes of ranvier (gaps between mylein sheaths so nerves jump from one node to another to speed up the nerve impulse)
56
the ___________ the diameter, the faster the speed of the nerve impulse
smaller
57
explain a reflex arc
1. receptors detect drastic change (like heat)
2. relays info to the sensory neuron
3. sensory neuron carries impulse to interneurons in spinal cord
4. interneurons relay information to the motor neurons
5. motor neurons act on effector to pull away
- reaches brain later, often involuntary
58
what is the electrical potential difference?
- rapid change across membrane detected every time the nerve becomes excited
59
what value is the resting membrane at?
-70 mV
60
when excited what value is the nerve at?
30 mV
61
what is action potential?
- the reversal of charge/potential resulting in a nerve carrying an electrical impulse
62
why is the resting membrane potential at -70 mV?
- neurons have a rich supply for anions and cations both in abd out of the cell
- membrane is more permeable to K+ so k+ diffuse out faster than Na+ diffuses in, resulting in an uneven charge where the inside the neuron is - and polarized
63
explain the process of a nerve impulse
1. dendrites receive stimulation that causes Na+ channels to open and if it crosses the threshold (~-55 mV) then the impulse continues
2. at 30 mV, more Na+ channels open and depolarization occurs
3. then, Na+ channels close and k+ channels open and depolarization is complete, and membrane begins to repolarize back to resting potential
4. hyperpolarization to -90 mV occurs and Na+/k+ pumps return it to its resting potential
- occurs in a wave of depolarizations and repolarizations
- refractory period must be completed before another action potential is produced
64
why must hyperpolarization occur?
- so that the nerve does not receive a second action impulse and impulse is not going backwards
65
explain the concept of a threshold in a nerve impulse
- stimulus must be above threshold to trigger response because the nerve has an all or nothing response
66
what is a synaptic cleft?
- space between neurons or neurons and effectors that the nerve impulse has to jump over
67
what are neurotransmitters?
- chemical signals that allow electrical impulses to pass
- can be excitatory (causes depolarization)
- can be inhibitory (causes hyperpolarization)
68
what is the process of a synapse?
1. small vesicles with the neurotransmitters are located in the axon and end plates of the presynaptic nerce
2. when nerve impulse passes across axon, vesicles release neurotransmitters into the cleft via diffusion
3. neurotransmitters bind to the receptors on the post synaptic neuron causing a depolarization of the dendrites and cell body of the post synaptic neuron
69
explain how acetylcholine is an excitatory neurotransmitter
- opens Na+ channels in post-synaptic neuron to cause depolarization and action potential
70
explain how acetylcholine is an inhibitory neurotransmitter
- opens K+ channels in post synaptic neuron to cause hyperpolarization
71
which enzyme gets rid of acetylcholine in the synaptic cleft?
- cholinesterase that is released from the post synaptic neuron to destroy acetylcholine and begin the recovery phase
72
what are EPSPs?
- excitatory postsynaptic potential
- depolarization brings membrane potential closer to threshold
73
define temporal summation
- 2 EPSPs in rapid succession on the same spot
- action potential happens faster
74
define spatial summation
- 2 EPSPs at the same time but at two different synapses
- combine and can trigger action potentian
75
define IPSPs
- inhibitory postsynaptic potential
- hyperpolarizations bring the membrane potential farther from the threshold
76
the summed effect of _______s and _______s determine whether action potential is reached or not
IPSPs and EPSPs
77
define excretion
- removal or toxic byproducts created in metabolic processes
78
what do the kidneys excrete?
1. ammonia (from deamination)
2. urea (ammonia with carbon dioxide)
3. uric acid (from breakdown of nucleic acids)
79
what does the urinary system consist of?
- 2 kidneys
- 2 ureters (tubes of smooth muscle that move urine from kidneys to bladder)
- a bladder (hollow sac containing urine with a urinary sphincter)
- uretha (tubule connected to the bladder where urine leaves the body)
- renal artery and vein
80
what are the three layers of the kidney?
1. cortex
2. medulla
3. renal pelvis (with vessels that join the kidney to the ureter and blood vessels)
81
what are nephrons?
- functional units of kidney
- where filtration and re absorption occur
- span the cortex and medulla regions
82
what is the purpose of the urinary system?
- filters blood and removes waste to be excreted
83
what are the parts of the nephron?
- glomerulus (high pressure capillary bed that is the site of filtration with an afferent arteriole and efferent arteriole)
- bowman's capsule (cup like structure to catch filtrate)
- proximal tubule
- loop of henle
- distal tubule
- collecting duct
- perturbular capillaries around the nephron to reabsorb nutrients
84
what is urinalysis?
the formation of urine
85
what are the four stages of urinalysis?
1. Glomerular filtration (movement of water and solutes exit blood and go to nephron)
2. tubular reabsorption (water and other useful solutes are resabsorbed into the blood)
3. tubular secretion (additional wastes are moved into the filtrate)
4. water reabsorption (water is removed from filtrate)
86
explain glomerular filtration
- blood pressure forces water and urea and salts from the blood into the bowmans capsule
- glomerulus capillaries are pourous and permeable to small solutes that collect in the bowman's capsule
- filtration is non-selective
87
explain tubular reabsorption
- because glomerulus filters our essential molecules that need to be reabsorbed, the proximal tube actively transports Na+ out of the nephron into the intercellullar spaces and Cl- ions follow to create an osmotic force so water moves away from the nephron and into the capillaries via diffusion
- the descending loop of henle reabsorbs the water and ions from the filtrate because the medulla environment is high in salt so water diffuses into the capillaries
- cells are less permeable
to ions so the
concentration gradient is
maintained and water is
still reabsorbed
- the bend at the loop of henle is slightly permeable to ions as Na+ move into the capillaries and then in the thick part of the ascending loop of henle, the opens are actively pumped out of the filtrate
- distal tube then reabsorbs more depending on the needs by using anions moved through electrical attraction to use osmosis to reabsorb water
88
explain tubular secretion
- distal tube actively transports K+ and H+ into the nephron to balance pH
- foreign substances are secreted and nephron cells synthesize ammonia into the urine to ensure that the filtrate is not acidic
89
explain water reabsorption
- occurs in the collecting duct to allow water to be reabsorbed before filtrate is sent to the bladder
- urine transported to the ureter to carry it to the bladder
90
which neurotransmitters does cocaine affect?
- epinephrine
- dopamine
- acetylcholine
91
how does cocaine affect the body?
- epinephrine absorption is blocked so it remains in the synapse leading to hyperthermia, increased blood pressure and a heart attack
- reuptake of dopamine is blocked because cocaine binds to the dopamine transporters resulting in euphoria
- acetylcholine's Na+ channels are blocked so there is no pain
92
which neurotransmitters does heroin affect?
- dopamine
93
how does heroin affect the body?
- stops release of inhibitory neurotransmitters (opiate receptors) so dopamine is released resulting in sedation
94
which neurotransmitters does THC in weed affect?
- dopamine
95
how does THC in weed affect the body?
- mimics the anandamides that active the cannabinoid receptors to stop inhibitory transmitters so dopamine is released and slows down movement
96
which neurotransmitters does alcohol affect
- GABA
- glutamate
97
how does alcohol affect the body?
- GABA becomes more potent with alcohol and inhibits and decreases the firing of post-synaptic cells
- glutamate, as an excitatory neurotransmitter, alcohol binds to its receptors to prevent it binding to the cell
