biol 1102 exam 3

what does the endocrine system regulate

regulates an organisms response to the environment through the release of hormones

Hormones

signaling molecules that are transported to regulate physiology, development, and/or behavior

glands

groups of cells functioning together

hydrophilic

water soluble; peptide and amine hormones. derived from amino acids, short chains. can move around easily in cytoplasm and blood. more abundant and more diverse in their actions

hydrophobic

steroid hormones (lipid derived and fat soluble) — derived from cholestrol. steroid hormones cannot evolve through changes.

how to peptide hormones enter cell

bind to cell surface receptors

how to steroid hormones enter cell

diffuse into target cell and bind to intracellular receptors

endocrine signaling

hormones travel to distant parts of the body

paracrine signaling

cell signals are recieved by nearby cells

autocrine signaling

cell signals are recieved by the cell that produced them

contact-dependent signaling

the ligand and receptor are both membrane bound. occurs in adjacent cells

endocrine glands

secrete signals into the extracellular fluid and into the blood

exocrine glands

have ducts that carry their products to the outside of the body or a body cavity ex. salivary, sweat glands

process of signaling

1. biosynthesis of a hormone

2. storage/secretion of hormone

3. transport of hormone to transport cell

4. reception of hormone when binding to receptor

5. relay and amplify signal via signal transduction

6. resulting in cellular response

hormone levels in blood depend on

rates of synthesis and removal through catabolism and excretion

blood sugar regulation

• negative feedback loop

• levels are maintained by insulin and glucagon

  • release insulin when BG levels are high and glucagon when BG levels are low

Type 1 diabetes

autoimmune condition where the body attacks cells in the pancreas that product insulin

what happens when insulin binds to receptor

insulin binds and glucose enters. promotes protein storage and inhibition of protein degradation. increases lipid storage and decrease lipolysis

type 2 diabetes

when cells do not respond to insulin. pancreas produces more insulin to compensate until it cant keep up and then it produces less insulin.

one hormone can trigger…

different responses in different types of cells (fight or flight response)

rosalyn yalow

developed radioimmunoassay, a method to measure hormones and other substances in the blood.

neurohormones

hormones made in and secreted by neurons whose cell bodies are in hypothalamus (amine/peptide hormones). cell bodies of neurosecretory cells extend axons into posterior pituitary. axons release hormones into bloodstream

releasing hormones

secreted by cells in hypothalamus into small blood vessels that travel to anterior pituitary gland. AP releases releasing or inhibiting hormones into bloodstream that control tropic hormones (there is hierarchy of hormones)

tropic hormones

hormones that control the release of other hormones

how does a neuron transmit information

1. stimuli are recieved by dendrites and cell body

2. synaptic stimulu summed at axon hillock

   1. action potential conducted at axon terminal, where there is release of neurotransmitter. bind to postsynaptic cell for new signal

membrane potential

charge difference across cell membrane (source of potential energy)

resting potential

the steady state in neurons when a neuron is not sending a signal

graded potential

temporary changes in membrane voltage of a cell, where magnitude of change is proportional to strength of stimulus

action potential

sudden, large transient reversal in membrane potential, used to send signals to other neurons or cells

sodium-potassium pump & resting membrane potential

sodium in, potassium out — requires ATP. sodium and potassium (more K+ channels) leak channels as well. high sodium outside high K+ inside —> results in net negative charge inside cell

stretch-gated ion channels

open when membrane is deformed by physical forces

chemically-gated ion channels

open or close when specific chemical binds to channel — important in chemical synapses

voltage-gated ion channels

open or close in response to change in membrane potential — important in axons

hyperpolarization

increase in magnitude or membrane potential

depolarization

reduction in membrane potential — becomes less negative

neurons generally encode

information in action potential frequency (how many occur per unit of time) not amplitude (amount of voltage change per action potential)

refractory period

state of recovery that occurs after neuron has fired action potential. another action potential cannot be created

events at chemical synapse

1. synaptic transmission through action potential

2. depolarization at axon terminal and opens Ca2+ channels

3. vesicles fuse with presynaptic membrane and release neurotransmitters

4. neurotransmitters bind with receptors on post synaptic cell opening channels to allow in ions and changing membrane potential

5. neurotransmitters are re-absorbed into presynaptic terminal and stored in vesicles

EPSP

depolarize postsynaptic neuron

IPSP

hyper-polarize postsynaptic neuron

temporal summation

multiple epsps arrive quickly at a single synapse and set off an action potential (added together)

spatial summation

single EPSP at two or more different synapses set off an action potential

oligodendrocytes

in brain and spinal cord — wrap around axons. produce covering of myelin

shwann cells

in other locations besides brain/spinal cord. same function as oligodendrocytes

astrocytes

contribute to blood-brain barrier; protecting brain from harmful chemicals; aid in repair and regeneration of neurons

microglia

provide nervous system with immune defenses

myelin

insulating sheath made up of proteins and fats

myelination

speeds signal transmission along axon through saltatory action potentials. node of ranvier has buildup of charges

gliobastoma

most common and aggressing brain tumor known for rapid growth and infiltration of surrounding brain tissue —> forms from astrocytes

multiple sclerosis

autoimmune disease where myelin sheaths of nerve cells in brain/spinal cord are destroyed causing inflammation and scarring. causes difficulty with movement and muscle control

absolute refractory period

Na+ channels are activated and cannot produce another action potential

relative refractory period

Na+ channels are inactivated and a new action potential can only be generated with a very large stimulus

sensory receptor proteins

found in membranes of sensory receptor cells and respond to stimuli by opening or closing ion channels

ionotropic receptors

ion channels that open or close in direct response to stimulus

metabotropic receptors

open or close ion channels indirectly via signaling cascade

stimulus for hearing

sound waves

human ear process

1. pressure waves go to tympanic membrane and then ossicles

2. brings to oval window and converts pressure waves into fluid waves within cochlea

3. pressure waves from ossicles cause membranes between chambers to flex.

   1. flexing of basilar membrane bends stereocilia on hair cells in organ of corti

hair-cells process

1. when k+ channels open, cell depolarizes

2. opens Ca2+ channels and releases neurotransmitters

3. when bent in opposite direction, channels close

have mechanoreceptors

sensing sounds of different freqs

low freq —> far down

high —> closest to tympanic membrane

process of vision

1. light travels thorugh ganglion, amicrone, bipolar, and horizontal cells

2. absorbed by rods and cones at back of retina

3. visual information processed

   1. converges on ganglion cells (only cell that can fire action potentials)

what happens to rhodopsins when they detect light

retinal changes shape which triggers signaling cascade

process of detecting light

1. in absense of light, Na+ channels open and create depolaring dark current

2. rhodopsin absorbs light energy

3. transducin to exchange gtp for gdp

   1. cell hyperpolarizes since Na+ channels close

bipolar cells

synapse with rod or cone cells and relay responses to ganglion cells

ganglion cells

send their axons out of the eye in the optic nerve

amacrine and horizontal cells

modify electrical signals as they pass from photoreceptor to ganglion cells

skeleton

a structure that serves functions related to support, protection, or locomotion

hydrostatic skeleton

consist of fluid filled body compartments

exoskeleton

hard substance outside of body

endoskeleton

hard substance inside of body

tendons

muscle to bones

ligaments

connect bone to bone — coordination

organization of muscles

1. many muscle bundles

2. surrounding by blood vessels

3. sounded by connective tissue

4. muscle fibers

5. muscle cells

6. myofibrils

thin filament

actin molecule wrapped with tropomyosin

interaction between actin and myosin filaments

overlap to form myofibrils; when Ca2+ binds to troponin, causes tropomyosin to move and expose binding sites

muscular contractions process

1. ca2+ released from reticulum and binds to troponin — exposes myosin binding sites

2. myosin heads binds to actin — release P1 and initiates power stroke

3. during stroke, myosin head changes conformation — filament slides past one another

4. ADP released; ATP binds to myosin causing it to release actin

5. ATP hydrolized

6. Ca2+ returned and muscle relaxes

7. if remaining Ca2+ available, process continues

how does an action potential generate a muscle contraction

1. action potential results in release of acetylcholine and depolarization

2. depolarization leads to release of Ca2+

3. Ca2+ binds to troponin causes movement in tropomyosin —> eventually leads to shortening of muscles

innate immunity

all present/on; provides general nonspecific defenses against many types of pathogens, does not depend on prior exposure to pathogen

adaptive immunity

specific to a given pathogen, remembers past infections and gives a stronger response when pathogens are encountered again, unique to vertebrates

lamellar granules

second layer of skin; produce fat and fills gaps between cells. produce defensins, antimicrobial peptides that tear holes in things

mucus membranes

secrete mucus on exposed surfaces that are not skin, contain several heavily glycosylated proteins that hold water and thus form gels, trap foreign agents and are often pushed out or eliminated (sneezing)

macrophages

largest immune cells (great eater), just below skin, in spleen, and liver, engulf invaders and general celluar debris

neutrophils

most abundant immune cells in blood, only live for a few days, release antimicrobial proteins from granules

neutrophil extracellular trap

a net of DNA bound with proteases to trap and kill microbes

pattern recognition receptors

proteins on the surface of phagocytes that recognize and bind to molecules commonly found on pathogens but not on host cells

pathogen associated molecular patterns

chitin, double stranded RNA, peptidoglycan

toll-like receptors

type of PRR

redness

increased blood flow through vasodilation

swelling

histamines released by mast cells make blood vessel cell walls more permeable and fluid leaks into damaged tissue, bringing white blood cells

heat

also from increased blood flow, increases cellular metabolism

pain

release of chemicals such as histamines that stimulate nerve endings

mast cells

large cells that circulate below the skin and contain small molecules called histamines (release of them cause inflammation)

cytokines

small chemical messengers released by cells such as macrophages. detected by receptors on cell surface. immune cells can detect location of cytokine releasing cells by following their concentration gradient

the complement system

1. groups of proteins make holes in bacterial membranes causing lysis

2. complement proteins coat the bacteria (opsonization). positive charges on proteins make it easier for phagocytic cells to engulf them

3. cell signaling through histamines

innate immune system cells that recognize general features on the surface of…

cancerous or virus infected cells

response 1 of innate immune system

attach directly to target cell. the NK cells release small cytoplasmic granules of proteins and proteases that can cause target cell to die

response 2 of innate immune system

release cytokine from other cells. cytokines send signals out to B and T cells triggering a more widespread immune response towards target cells (more common response)

dendritic cells

phagocytic cells present just below skin and mucus membranes. takes fluids to determine if bacteria or virus are present. if present stores large pieces of pathogens and other proteins found. then travels through lymphatic system to a lymph node and can activate immune system.

lymphatic system

network of vessels present through your body. takes interstitial fluid and returns it to blood. It also plays a crucial role in transporting immune cells and filtering pathogens through lymph nodes.

what is the field of ecology

studies interactions among organisms, as well as between organisms and their environments, considers abundance and distribution of species

population

collection of all INTERBREEDING individuals of the same species living together in the same area