NPB 110A midterm 3

two major control systems in the human body

nervous and endocrine

what does the nervous system use as its signaling molecule

neurotransmitters

what does the endocrine system use as its signaling molecule

hormones

does the nervous system have a low or high affinity between ligand and receptor

low

does the endocrine system have a low or high affinity between ligand and receptor

high

what type of signals does the nervous system send out (two key words)

rapid and short-acting

what type of signals does the endocrine system send out (two key words)

slower and long-lasting

does the endocrine system use direct or indirect connections and via which delivery method

indirect via bloodsteam

does the nervous system use direct or indirect connections and via which delivery method

direct via synapses

what are the important stuff that the endocrine system is responsible for

homeostasis (insulin), growth and development, reproduction (testosterone and progesterone), and metabolism (thyroid hormone)

hormones defintion

chemicals released by one cell that travel through blood to reach a target cell far away

where are hormones released from

endocrine glands

goiter

enlargement of thyroid gland via a lack of iodine, under active thyroid, and hyperthyroidism

three types of hormones

amines, steroids, and peptides

amines (hormones) structure and examples

tyrosine based signaling molecules, examples are NTs and T3 ad T4

steroids (hormones) structure and examples

signals made from cholesterol, examples are cortisol and testosterone

peptides (hormones) structure and examples

short protein signalers that are hydrophilic; examples are insulin, glucagon, GH, and agiotensin

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

Composed of: Microtubules, Microfilaments, Intermediate Filaments

Microfilaments

Long, thin fibers that function in the movement, muscle contraction and support of the cell

Composed of Actin

Actin

thin filaments, helical polymers (just 2 layers), in microvilli, can bind GTP

Have Polarity:

barbed end (thicker side): + end

other end (thin side): - end

Microtubules

A hollow rod composed of tubulin proteins that make up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.

Have polarity:

+ end towards nucleus

- end toward microvilli

Intermediate Filaments

A component of the cytoskeleton that includes all filaments intermediate in size between microtubules and microfilaments.

Rope like and can intersect.

Important for structure, inside nuclear lamina of cells

actin dynamics

actin subunits hit each other and begin to form a rod like structure. Continue growing until steady state: actin coming off=actin coming on (length doesn't change)

Arp 2/3 complex

nucleates assembly of actin subunits (skips adding phase) to form a web associated at the minus end

bacteria can highjack this system for movement

Dynamic instability of microtubules

GTP promotes monemer tubulin elongation, so when GTP is present growth is promoted

Over time however GTP will hydrolize to GDP and GDP promotes disassembly

Microtubular motor proteins

Kinesin: move toward + end

Dyneins: move toward - end

microfilament motor proteins

myosin

uses ATP to move

move at different speeds bc different types

why do we need motor proteins to move cargo?

diffusion is slow and unorganized, organelles need to be in specific places (location matters)

Example of motor movement

melanosome movement in pigment cells

decrease cAMP- pigment moves in (smaller)

increase cAMP- pigment moves out (larger)

Lysosome's moved by what?

dynein

Mitochondria moved by what?

both dynein and kinesin

synapse/synaptic cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell.

where are peptides synthesized at (and how are they encoded for)

ER and encoded by genes that have ER signal peptides

how are peptides released

via exocytosis

peptides can travel freely in blood (true or false)

true

are peptides hydrophilic or hydrophobic

hydrophilic

are steroids hydrophilic or hydrophobic

hydrophobic

do peptides lead to fast or slow responses to change and how

fast via changes in activity of existing proteins (like phosphorylation)

do steroids lead to fast or slow responses to change and how

slow via affecting gene expression that then makes new proteins

what are the two main characters of the neural and endocrine system

hypothalamus and pituitary

what are the three main functions of the hypothalamus

receives a large number of inputs that leads to afferent pathways, integrate signals from different environments to make a endocrine response, and directly contorl the pituitary which leads to a efferent pathway

what is the main function of the pituitary gland

secretes 8 well characterized hormones into the bloodstream controlling an array of physiological functions

how many posterior pituitary hormones are there

two

how many anterior pituitary hormones are there

six

skeletal muscle structure

Muscle -> muscle fibre bundle -> muscle cells/fibers -> myofibrils -> myofilaments (actin & myosin)

skeletal muscle development

myoblast -> 1º fibre -> 2º fibre -> mature fibre

Tendons

Connect muscle to bone for a smooth transition

myoibrils

bundles of contractile elements composed of a population of sarcomeres

thin filaments- actin

thick filaments- myosin

Sarcomere

Contractile unit of muscle

Which parts of the sarcomere shorten during contraction?

sarcomere as a whole

H zone-just myosin

I band- between 2 myosins, all actin

Which parts of the sarcomere stay the same length during contraction?

A band, whole myosin

what happens during muscle contraction?

myosin heads form cross-bridges with the actin filaments in plus direction

thin filaments

mainly actin, but also troponin (T, C, I) and tropomyosin

addition of calcium to thin filaments

troponin C binds with calcium to remove inhibitory tropomyosin. Allows for myosin heads to bind to actin for contraction

sarcoplasmic reticulum

Organelle of the muscle fiber that stores calcium.

calcium release regulation

1. calcium channels open to release acetyl CoA neurotransmitter

-acetyl CoA binds to receptors in muscle cell

2. binding allows for the opening of K and Na channels to depolarize the membrane

3. creates an action potential that travels through T tubule

- results in positive part inside cell

4. DHP on T-tubule opens which opens Ryr receptor on sarcoplasmic reticulum

5. calcium floods in to allow for binding of actin and myosin --> muscle contraction

Steps needed for muscle contraction

1. Calcium

-binding of troponin C to bind actin to myosin

2. Myosin Binding

-binding to actin allows for Z-lines to get closer

3. ATP binding

-allows for myosin to release

myosin power stroke

1. when calcium shows up, myosin grabs actin (Pi released)- crossbridge

2. power stroke, moves head (ADP released)

3. Rigor (low energy form)

4. unbinding of actin and myosin (ATP required)

5.cocking back of myosin head (high energy form)

Calcium reuptake

via SERCA on sarcoplasmic reticulum

uses ATP

what is the main function of hypothalamus

site of neural integration

what is the main function of the pituitary gland

provides hormonal output to body

what is the purpose of hypothalamic neurons

secretes the two posterior pituitary hormones

what is the purpose of hypothalamic hormone

stimulates or inhibits release of the six anterior pituitary hormone

trophic hormones

act as a growth factor and/or mitogen on their farget tissue

tropic hormone

regulate hormone secretion from their target tissue

describe the process that leads to the secretion of TSH

first the TRH is released that then activates the anterior pituitary to then release TSH and then it goes to the thyroid gland that then results in growth

neurosecretory cells

neurons that translate electrical nerve signals into hormonal messages

hypothalamus

brain region controlling the pituitary gland

receives inputs and integrates signals for response

pituitary gland

The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.

secretes hormones into blood

posterior pituitary

makes no hormones, storage site; neurotransmitter's release the hormone

anterior pituitary

makes lots of hormones, travels through a tiny blood vessel

Endocrine control

first order loop (1 hormone used-posterior pituitary)

second order loop (2 hormones used- anterior pit)

third order loop ( 3 hormones used)

direct (no neural input)

tropic hormones

hormones that stimulate other glands to release their hormones and grow

Thyroid hormones (T3 and T4)

Iodine-containing hormones that control the body's metabolic rate

Effects of thyroid hormone

primary determinant of metabolic rate (regulate body temperature); permissive for GH, epinephrine, norepinephrine

Graves disease

an autoimmune disorder that is caused by hyperthyroidism and is characterized by goiter

central nervous system

brain and spinal cord

peripheral nervous system

the sensory and motor neurons that connect the CNS to the rest of the body

somatic nervous system

the division of the peripheral nervous system that controls the body's skeletal muscles

autonomic nervous system

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). have no control

parasympathetic nervous system

rest and digest

sympathetic nervous system

fight or flight

Neurotransmission in autonomic pathways

paracrine signalling using norepinephrine

SNS stimulates adrenal medulla to release epinephrine

epinephrine & norepinephrine can activate the same receptors

fight or flight response effects

pupil dilation

increase heart rate

decrease digestion

release of fuel molecule from liver into blood

endocrine system and stress

activates adrenal cortex

releases cortisol

increases blood glucose levels, blood fat, amino acid levels

nervous system and stress

activates adrenal medulla

makes adrenaline (epinephrine and norepinephrine)

Cushing's syndrome

hypersecretion of cortisol

skeletal muscle and insulin

stimulates glucose uptake (doesn't need insulin)

diabetes

hyperglycemia

defects in insulin secretion or action

Diagnosing Diabetes

normal level: 100

fasting blood glucose of 126

oral glucose tolerance test of 200 @ 2hrs

random level of 200

type 1 diabetes

diabetes in which there is no beta cell production of insulin--the patient is dependent on insulin for survival

type 2 diabetes

progressive disorder in which body cells become less responsive to insulin

still have beta cells, just working really hard

Insulin

A protein hormone synthesized in the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into tissues

beta cells: insulin secretion

alpha cells: glucagon secretion

delta cells: inhibitory

GLUT4 transporter

"Doorway" for glucose found in muscle cells and fat cells that opens after insulin binds to the insulin receptor

effects of insulin- carbohydrates

1. enhances glucose uptake via GLUT4

2. increases liver and skeletal muscle glycogenesis (store glycogen)

3. inhibits liver glycogenolysis (stop breaking down gluc)

4. inhibits gluconeogenesis (stop making new gluc)

increase insulin=decrease glucose in blood

effects of insulin- fat

increase insulin=decrease fatty acids in blood

effects of insulin- protein

increase insulin=decrease amino acids in blood

risk factors for type 2 diabetes

Obesity

Sedentary lifestyle and inactivity

Family history

Race (African American and Hispanic)

Age

History of gestational diabetes

insulin resistance

the inability of the cells to respond to insulin

leads to decrease uptake of glucose in muscle, deregulation of glycolysis but liver wont stop making new glucose

describe the ACTH release pathway

first the hypothalamus secretes the CRH that then activates the anterior pituitary to release ACTH and then it goes the adrenal cortex that then leads to the secretion of cortisol