human phys exam 1

what is cell differentiation?

transforming unspecialized cells into specialized cells

what is a tissue?

collection of specialized cells that carry out certain functions

what are the four tissue types?

• epithelial tissue

• connective tissue

• nervous tissue

• muscle tissue

what is epithelial tissue?

tissue that covers the outer and inner surfaces of many internal organs and body cavities

what is the function of epithelial tissue?

• secretion/absorption of ions + organic materials

• protection

what is connective tissue?

• connects, anchors, and supports structures of the body

• forms extracellular matrix between cells (intercellular space)

what are the types of connective tissue in adults?

• loose (areolar)

• dense irregular (skin)

• dense regular (tendon + ligament)

what are types of special connective tissue?

• adipose

• cartilage

• blood

• stem cells

what are the types of stem cells?

totipotential: can develop into any cell type

pleuripotential: can develop into any cell type, except placenta

multipotential: can develop into diff families of cells (but limited)

oligopotential: can develop into only cells within one family

unipotential: can develop only into one cell type

what is nervous tissue?

made up of neurons and neuroglia (glial cells)

what are the two parts of the nervous system?

central nervous system (CNS) + peripheral nervous system (PNS)

what is the function of nervous tissue?

integrate bodily functions and integrate the external + internal environment

what is muscle tissue?

contracts to create movement and heat

what are the three types of muscle tissue?

• skeletal

• cardiac

• smooth

what is skeletal muscle tissue?

• voluntary (somatic nervous system)

• produces movement of limbs or trunk

what is cardiac muscle tissue?

• involuntary (autonomic nervous system)

• generates heart contractions to pump blood into circulation

what is smooth muscle tissue?

• involuntary (autonomic nervous tissue)

• makes up parts of walls of tubes

• contraction shortens length/decreases diameter

what are the different types of body fluids?

intracellular fluid (67%): fluid contained within all cells

extracellular fluid (33%): fluid outside of cells

• interstitial fluid (26%): fluid that lies around + between cells

• plasma (7%): fluid portion of blood

what is homeostasis?

process of maintaining physiological variables of a body in a stable environment within a predictable range (aka set points)

what are set points?

predictable range that physiological variables od the body are maintained

what is the difference between steady state and equilibrium?

steady state: requires input of energy to maintain consistency

equilibrium: no input of energy required to maintain

what is dynamic constancy?

given variable may fluctuate in the body short term, but stable and predictable in the long term

what is the circadian rhythm?

variables change dramatically over 24 hr period, but system is overall balance

can set points change?

set points are adaptive to new conditions or in response to illness

ex: during fever, body temp set point increases to fight pathogens

what is the difference between feedback and feedforward regulation?

feedback regulation: body reacts after disturbance/stimulus

feedforward regulation: body anticipates future change in system and initiates corrective action before change actually occurs

what are the two types of feedback?

negative feedback: effectors cause an effect to turn off effector

positive feedback: effectors cause an effect to turn on/amplify effector

what is a reflex?

specific involuntary built-in response to a particular stimulus

what is the reflex arc?

stimulus —> receptor —> afferent pathway —> integrating center —> efferent pathway —> effector —> response

what is the difference between afferent and efferent?

afferent: sensory

efferent: motor

what is a stimulus?

detectable change in internal or external environment (e.g., change in temp, concentration, blood pressure)

what is a receptor?

detects environment change

what is the integrating center?

receives a signal from the receptor via. afferent pathway and responds to the signal

what is the effector?

receives command from the integrating center via. efferent pathway and executes it

why do we see redundancy in function of efferent pathways?

• reach set point quicker

• accuracy

• disease (in case one response pathway doesn’t work)

what type of tissue are bones of?

connective tissue

how are bones made?

ossification: bone formation

membranous bone: bone builds along connective sheet

cartilage bone: cartilage turns to bone via. ossification

what are osteoblasts vs. osteoclasts vs. osteocyte?

osteoblasts: cells responsible for bone formation

osteoclasts: bone remodeling → dissolve bone and releases phosphate + calcium

osteocyte: cell that maintains bone through lifetime; former osteoblast in lacunae; maintenance and turnover of bone

what is the structure of osteoblasts?

lacunae

central canal

haversion system

lamellae

canaliculi

• lacunae: cavity

• central canal: cerebrospinal fluid-filled space that runs through the spinal cord

• haversion system: blood vessels, nerves, and lymphatics

• lamellae: rings of bone

• canaliculi: canals that allows for cells to communicate with each other

what is osteoporosis? which is the primary demographic it affects?

osteoporosis: breakdown of bone

• mostly affects post-menopausal women: decline in estrogen → overactive osteoclasts

  • (estrogen inhibits osteoclasts)

what is diffusion?

• relies on kinetic energy & brownian (random) movement to move molecules down a concentration gradient

• **net diffusion stops @ equilibrium

what is osmosis?

passive movement of water towards high concentration of solutes

what is hypoosmotic vs. hyperosmotic?

• hypoosmotic: losing water

• hyperosmotic: gaining water

what are ion channels?

• made up of multiple protein subunits for passage of ions

• ligand-gated ion channel (ex: nicotinic for acetylcholine)

• voltage-gated ion channel (ex: K+)

• leaky ion channel

what is facilitated diffusion?

use of channel proteins or carrier proteins for passive transport

what are characteristics of facilitated diffusion?

1. specific: only passes certain molecules

2. passive: down concentration gradient

3. saturates: concentration gradient relates to speed (but only until all carrier proteins are bound)

what is active transport?

• movement of molecules up/against concentration gradient using ATP (direct input of energy)

• sodium-potassium pump: 3Na+ out, 2K+ in

what is secondary active transport? what are the different types?

secondary active transport: using energy generated from gradient from primary active transport (indirect) to power active transport of another molecule

• cotransport/symport: moving molecules in same direction

• countertransport/antiport: moving molecules in opposite direction

What are the four types of cell communication?

hormone: long distance, travels through circulation

neurotransmitter: short distance, chemical released from neuron

paracrine: target cell in close proximity (within same tissue type)

autocrine: target cell in same cell that released autocrine substance

what is a neurohormone?

chemical messenger produced by neurons and can be released in the bloodstream

how can autocrine be a form of negative feedback inhibition?

ex: insulin secreted into bloodstream but can also inhibit the cell that released it

what is signal transduction?

process of signal transmitted through a cell via. series of molecular events (changing shape/form of signal); results in physiological response

what is affinity?

•  how well the ligand binds to the receptor; measured by concentration of ligand

• low conc. ligand binds to high affinity receptor

• high conc. ligand binds to low affinity receptor after high affinity receptors are saturated

what is saturation?

degree to which receptors are occupied

what is competition?

 2 or more ligands present that can bind to the receptor

what is an antagonists vs. agonist?

• antagonist: competes but does not activate signaling (e.g., antihistamines, beta-blockers)

  • prescribe an antagonist when pathway occurs too much in the body

• agonist: competes but does activate signaling (e.g., morphine, decongestants)

  • prescribe an agonist when the pathway does not occur enough in the body

what is the difference between down-regulation and up-regulation?

down-regulation: # of receptors decreases —> cell is less-sensitive

up-regulation: # of receptors increases —> cell is more-sensitive?

why does down-regulation occur?

to reduce target cell’s responsiveness to frequent/intense stimulation from high extracellular conc. of messenger is maintained for prolonged period of time

why does up-regulation occur?

to increase likelihood of binding occurrence when cell is exposed to low conc. of messenger for prolonged period of time

how does endo/exocytosis relate to down/up-regulation?

endocytosis: driving downregulation by reducing surface receptors by internalization

exocytosis: driving upregulation by increasing surface receptors by delivering new ones

what are the three characteristics does ligand-receptor binding demonstrate?

• specificity

• saturation

• competition

what are the two types of receptors?

membrane-bound receptors: embedded to cell surface; binds to water-soluble ligands

• trigger rapid, short-lived responses via signal transduction cascades

• e.g., insulin, amino hormones-epinephrine, neurotransmitters-acetylcholine

intracellular receptor: located inside the cell (cytoplasm/nucleus); binds to lipid soluble ligands that can cross the membrane

• slow, but long-lasting genomic effects to inhibit/facilitate transcription + gene expression

• e.g., steroids-testosterone, estradiol, thyroid hormones, vitamin D

what are the different types of effects intracellular receptors have?

genomic effects: slow, but long-lasting; inhibit/facilitate transcription + gene expression

non-genomic effects: less long-lasting; affects cytosol

what is a first messenger?

chemical ligand that binds to receptor

what is a second messenger?

molecule released/created inside the cell that activates a variety of pathways

what is a protein kinase?

enzyme that phosphorylates another protein → either activates/deactivates protein

what are the four types of extracellular receptors?

1. ligand-gated ion channel

2. receptors that are enzymes (RTKs)

3. receptors that activates enzymes (JAKs)

4. G-protein coupled receptors (GPCR)

how do liganed-gated ion channels work?

• binding to ligand opens the ion channel

• ex: Na+, K+, Ca 2+

how do RTKs work?

1. ligand binding

2. dimerization

3. autophosphorylation

4. docking protein

5. enzyme is fully activated + activates signaling pathway

how do JAKs work?

JAKs: separate, non-receptor tyrosine kinases that associate with cytokine receptors.

1. cytokine (involved in immune response) binds to receptor

2. dimerization

3. trans-phosphorylation (cross-phosphorylation)

how do GPCRs work?

1. first messenger binds to receptor

2. G-alpha dissociates from beta-gamma dimer

3. G-a subunit exchanges GDP for GTP and activates effector protein

4. effector protein activates downstream cellular effects (as long as GTP and alpha subunit are present)

what is cAMP?

• adenylyl cyclase converts ATP —> AMP —> cAMP

• cAMP (second messenger) amplifies signaling cascade

what is the study of the normal function of the body?

physiology

what is the study of the diseased function of the body?

pathology/pathophysiology

what are the different shapes of epithelial cells?

• cuboidal

• columnar

• squamous

• ciliated

what are terms to describe different layers of epithelial tissue?

• simple

• stratified

epithelial cells rest on an extracellular protein layer called the ___,

basement membrane

what is the side of an epithelial cell’s membrane that faces and is anchored to the basement membrane?

basolateral side

what is the difference between tight junctions and gap junctions?

tight junctions: creates a barrier to prevent leakage between cells

gap junctions: create channels to allow movement of molecules between cells (communication)

what is a major component of extracellular matrix and constituted 1/3 of bodily proteins?

collagen

what is the connective tissue found in meshwork of cells and fibers underlying most epithelial layers?

loose connective tissue

what is the difference between the inside and outside of a cell membrane?

membrane potential

what is gating?

the process of opening and closing ion channels

what is a ligand?

specific molecule that binds to channel protein and directly/indirectly causes change to channel’s shape

what are voltage-gated ion channels?

membrane potential causes movement of charged regions on channel proteins which alters the shape of the ion channels

what are the driving factors of electrochemical gradients?

1. concentration difference

2. electrical (charge) difference

what are ligand-gated ion channels?

binding of a specific molecule changes shape of the ion channel

What are the two most common results of the binding of a first messenger to a ligand-gated channel?

• ion diffusion and a change in electrical charge across the membrane

• entry of Ca²⁺ (which can act as a second messenger)

what are the two most common effector protein enzymes regulated by G proteins?

adenylate cyclase

phospholipase C

Gq activation leads to the production of ___, a second messenger that activates protein kinase C

DAG

where does cytoplasmic IP₃ bind to? what does it result in?

• binds to receptors on endoplasmic reticulum

• results in diffusion of Ca²⁺ into the cytosol

what factors affect magnitude of solute flux with mediated-transport systems?

• how saturated the binding sites are

• how quickly the transporter changes conformation

• number of transporters present

• solute concentration

how does Na⁺/K⁺ pump work?

1. 3 Na⁺ binds to 3 binding sites on carrier protein

2. ATP hydrolysis

3. conformation change decreases Na⁺ affinity and releases to extracellular fluid

4. new conformation increases affinity for K⁺

5. K⁺ binding results transporter to return to original shape and release 2 K⁺ to inside cell