HOMEOSTASIS, ORGANIZATION, & intro to NS/ES Flashcards
define homeostasis
tendency to resist change in order to maintain a stable relatively constant internal envir
smallest unit that can perform the basic functions required of all living things
cell
tissue
groups of specialized cells working together for the same function
types of tissues
- epithelial
- muscular
- connective
- nervous
epithelial tissue
fx: exchanging materials btwn cell & envir, protection, & secretion
- epithelial sheets form boundaries
- glands secrete in response to stimuli
-
endocrine: ductless ➞ secrete directly into bloodstream
* ex: pancreas -
exocrine: secrete through ducts
- sweat glands
- sebaceous glands (oil)
muscular tissue
fix: cells specialized for contracting ➞ tension & movement
3 types:
-
Skeletal: movement of skeleton, locomotion
- most common - attached to skeleton all throughout body - jaw = strongest - Cardiac: contraction/pumping of heart
-
Smooth: contraction of openings or tubes
- ex: stomach, bladder, capillaries
Nervous
Fx: specialized cells for initiating & transmitting electrical impulses
- signal transduction & transmission
- communication, coordination, control
a. central: brain
b. peripheral: spinal cord, nerves
basic cell fxs
- obtaining food/nutrients/O2 from envir
- metabolism (cell resp)
- eliminating waste
- protein synthesis
- controlling material
- exchange/transport
- movement
- respond to stimuli
- reproduce
ER
membrane synthesis
- rough: protein synthesis
- no ribosomes
golgi complex
new proteins from ER are sorted & packaged for transport
lysosomes
cellular digestion of foreign substances & debris, detoxification
peroxisomes
fatty acid degradation
proteasomes
H2O2 production ➞ degrades intracellular proteins tagged by ubiquitin
connective tissue
connects, supports, & anchors
- majority of extracellular material w/ a few cells interspersed
- loose connective: attaches epithelial to underlying structures
- tendons: attach skeletal muscles to bone
- bone: gives shape, support, & protection
- responsible for blood production
- pelvis/femur = largest bones ➞ most blood production
- larger bones = strongest ➞ harder to break - blood: transports materials throughout body
- decrease in height throughout day due to compaction of connective tissue
body systems
- circulatory
- respiratory
- digestive
- skeletal
- muscular
- urinary
- nervous
- integumentary
- immune
- endocrine
- reproductive
control center for temperature
hypothalamus
homeostatic control system
- sensor detects deviations from set point
- afferent signal sends info from sensor into control center/integrator
- control center processes info
- efferent signal sends info from control center out to effectors, which carry out response
negative feedback
response reverses or causes opposite effect of original stimulus
intrinsic control systems
built into organs/tissues
- exercising increases CO2 ➞ smooth muscle of blood vessels in skeletal muscle dilates to increases blood flow & bring O2
extrinsic control systems
external system requiring coordinated regulation of multiple organs
- Low BP, detected by NS, increases HR and constricts vessels
- Hi BG, detected by endocrine system, exerts hormonal control
Pathophysiology
disease; abnormal functioning
feedforward mechanisms
activate homeostatic mechanism in anticipation of change based on pattern/routine
- no detectors/sensors/receptors
- can be rare/infrequent event ie heartbeat prior to physical exertion
- circadian rhythms ➞ internally driven by envir cues
direct cell to cell communication
-
gap junctions: transfer small mol/ions
- proteins
- electrolytes
- transient cell’s surface markers directly linkup
human BG (plasma)
~80mg/dL
glucose ↑
β cells release insulin
glucose ↓
𝝰 cells release glucagon
BG receptors
𝞪/β cells
BG control center
pancreas
BG effector
insulin/glucagon
largest glycogen storage
liver
paracrine secretions
nearby signaling - two or three cells away
- ex: estrogen
autocrine signaling
releases hormones that bind to itself
neurotransmitter secretion
across synaptic cleft
endocrine signaling
-
hormones: secrete into bloodstream can travel entire body
* hormone = extracellular signaling mol; acts at receptors in distal tissues
* only specific target cells with specific receptors can respond - neurohormones: hormone secreted from neuron into bloodstream
positive feedback
action amplifies initial change
- does not contribute to homeostasis
- moves syst away from set-point
- childbirth, AP, blood clotting, lactatio
NS vs ES:
anatomy
NS: “wired”
* physical structure
* continuity
ES: “wireless”
* dispersed
* not connected
NS vs ES:
chemical messenger
NS: neurotransmitters into synaptic cleft
* short distance
* close proximity
* fast
* short-lived
* speed
ES: hormones into blood
* distal cells
* long-acting
* duration
NS vs ES:
distance
NS: very short
ES: long, across entire body
NS vs ES:
specificity
NS: dependent on anatomy of neuron or target cell
ES: dependent on specificity of target cell binding receptors & responsiveness to hormone
NS vs ES:
speed
NS: rapid (milliseconds)
ES: slow (min-hrs)
NS vs ES:
duration
NS: brief (milliseconds)
ES: long (min-d+)
hormone
extracellular signaling mol that is released into blood & acts at its receptors in distal tissues in order to elicit a physiological response
neurotransmitter
secreted by neuron & acting directly on its target through synapse
* regulating excitable cells
synapse (synaptic cleft)
junction between 2 neurons
* short distance
* electrical synapse: 2 neurons connected by gap junction ➞ allow charge-carrying ions to flow directly in either direction
* chemical synapse: chemical messenger transmits info 1 way across a synapse
* can also be from a neuron to a muscle = neuromuscular junction (part of somatic nervous system, not ANS)
differences between hormone & neurotransmitter
- distance
- duration
- speed
similarities between hormone & neuromuscular junction
- signals
- chemical mol that transmits info
- bind to receptors
- main purpose = homeostasis
- mol can be both:
- ex: dopamine & N2O2
- both just functional mol ➞ only diff is how they act & where the body is putting the signal to use, not what they are made of
endocrine pancreas hormones
- insulin
- glucagon
- somatostatin
pituitary hormones
anterior:
* adrenocorticotropic hormone (ACTH)
* thyroid-stimulating hormone (TSH)
* growth hormone (GH)
* prolactin
* follicle-stimulating hormone (FSH)
* luteinizing hormone (LH)
posterior:
* vasopressin
* oxytocin
adrenal gland hormones
- catecholamines - epinephrine & NE
- glucocorticoids - cortisol
- mineralocorticoids - aldosterone
- dehydroepiandrosterone sulfate (DHEAS)
thyroid gland hormones
- thyroxine(T4)
- triiodothyronine (T3)
- calcitonin
parathyroid gland hormones
parathyroid hormone (PTH)
hormone secreted in white adipose tissue
leptin
hormone secreted in stomach
- gastrin
- somatostatin
hormone secreted in intestines
- cholecystoskinin
- secretin
- GLP-1
- GIP
hormone secreted in kidney
erythropoietin
hormone secreted in liver
insulin-like growth factor-1
hormone secreted by hypothalamus
- corticotropin-releasing hormone (CRH): stimulates anterior pituitary to secrete adrenocorticotropic releasing hormone ➞ stimulates adrenal to secrete glucocorticoids (cortisol)
- thyrotropin-releasing hormone (TRH): stimulates anterior pituitary to secrete thyroid stimulating hormone ➞ simulates thyroid to secrete T3/T4
- gonadotropin-releasing hormone (GnRH): stimulates anterior pituitary to secrete gonadotropins ➞ stimulate gonads to secrete sex hormones
- growth hormone-releasing hormone (GHRH): stimulates anterior pituitary to secrete GH ➞ stimulates liver to secrete insulin-like growth factor I (IGF-1)
pineal gland hormone
melatonin
hormone classifications
hydrophilic
1. the amines: amino acid derivatives
2. peptide hormones
lipophilic
1. thyroid hormones: derived from 2 tyrosines + iodine
2. steroid hormones: derived from cholesterol
the amines: amino acid derivative hormones
- dopamine, NE, & EP from tyrosine
- melatonin from tryptophan
peptide hormones
- all pancreatic hormones (insulin, glucagon, etc)
- all GI tract hormones (secretin, gastrin, CCK, GLP-1, GIP, etc)
- all hypothalamic releasing or inhibiting hormones (except dopamine)
- all anterior & posterior pituitary hormones
- angiotensin II
- insulin-like growth factor I
- erythropoietin
- atrial natriuretic peptide
- calcitocin
thyroid hormones
derived from 2 tyrosine + iodine
* thyroxine (T4)
* triiodothyronine (T3)
steroid hormones
modified cholesterol
* estrogens
* androgens (testosterone, anabolic steroids)
* progestins (progesterone, birth control)
* glucocorticoids (cortisol)
* mineralocorticoids (aldosterone)
* vitamin D (1,25 dihydroxy vitamin D3)
most hormones are ____ and therefore are _______ & act through ______
most hormones are peptide hormones
therefore are hypophilic
act through receptors on target cell surfaces
steroidogenesis
biological process of steroid hormone production
* steroidogenic enzymes make steroids from cholesterol
* steroids retain lipophilic properties but can now pass through cell membrane
* adrenal cortex:
* cholesterol
* progesterone
* cortisol
* aldosterone
* gonads
* cholesterol
* progesterone
* testosterone
* estradiol
steroid hormone receptors vs peptide hormone receptors
lipophilic receptors inside target cell cytoplasm or nucleus
peptide receptors on target cell surface
hydrophilic vs lipophilic hormone storage
hydrophilic can be stored in secretory vesicles after synthesis
* immediate release
lipophilic diffuse out of the cell as soon as synthesized
* once target cell receptor is signaled cell must start transcription & translation to synthesize new hormone
ex: epinephrine = amine ➞ immediate release in response to stress while cortisol takes time to synthesize
hydorphilic vs lipophilic hormone transport through bloodstream
hypophilic are soluble in plasma
lipophilic are bound to proteins as they circulate
* protein carries form temporary association
* can bounce off at any point
* no specific target cell/receptor location
* bathe every cell but only work on target cells with receptors
* body accounts for percentage always flowing in bloodstream when synthesis
hydrophilic vs lipophilic hormone metabolism & excretion
secreted hormones can be modified to become less active
hydorphilic can be cleaved by circulating general proteases
* peptides can be easily cleaved
lipophilic can be made more water soluble ∴ can be easily excreted in urine
* liver enzyme modifies
* normal lipophilic
secreted hormones can be modified to become more active
hydorphilic can be cleaved by specific proteolytic enzymes
* ex: angiotensinogen from liver reacts with renin in blood secreted by kidney to form angiotensin I which it cut by angiotensin converting enzyme from lung to made angiotensin II ➞ important in BP
lipophilic are modified by enzymes inside target cell
* ex: thyroxine (T4) rxts w/ deiodinase ➞ tri-iodothyronine (T3) = most active form
* ex: testosterone rxts w/ 5⍺ reductase ➞ dihydrotestosterone (DHT)
