BIOL 544 Exam 3

Active state of muscle

The formation of bonds between myosin and actin and subsequent internal shorting of contractile component, requires ca are 10-7M

Twitch

Brief increase in tension due to cross bridge activity

Tetanus

Internal and external tension reaches max levels

Muscle length and tension

Too short

Too short( low tension), optimal, too long (high tension)

Three metabolic pathways supply ATP for muscles

Creatine phosphate, glycolysis, oxidative phosphorylation

Types of skeletal muscle fibers contraction speed

Extraoccular muscle(7-8), gastrocnemius( 40 mesc), soleus (90)

Red fibers

Slow, small diameter, contains myoglobin, fatigue resistant

White fiber

Fast, large diameter, pale color, easily targeted

Oxidative muscle fibers

Gets ATP via aerobics metabolism

Glycolysis fibers

Gets ATP primary by anaerobic glycolysis

Muscle tissue types

Skeletal, cardiac, smooth

Smooth muscles

Present in tissues that require sustained contraction

Smooth muscle features

Homeostatic role, tonic and slow contractions, not striated, dense bodies instead of Z lines, Ca+2 required for contractions

Types of smooth muscle

Visceral/unitary or multi unit

Multi unit

For fine control, respiratory airways, large arteries

Single unit smooth muscle

For less fine control, FI tract and uterus

Smooth muscle location

Visceral organs, arteries, veins, iris of eye

Increased muscle tension

Ca binds to CaM and CAM activates MLCK

Decreased muscle tension

Ca unbinds from CaM, MLCK inactivates

Mechanism of smooth muscle relaxation

1. Repolarization of SR, closing of Ca channels 2. Pumping Ca into SR

Myosin light chain phosphates(MLCP)

De phosphorylates myosin light chain, inhibits myosin ATPase

Neural stimulation

Arch in skeletal, many in smooth( differ by location)

Stress-relaxation response

Smooth muscle stretches and adapts t new length, can contract

Phasic contaction

Brief stimulation, quick ca elevation, quick loss of phosphorylation

Tonic Contraction

Continued stimulation, continued Ca elevation, continued phosphylation, contains latch stage

Insect muscle Types

Only striated muscle

Insect muscle components

Tonofibrillae, apodeme, no tendons

Tonofibrillae

Cytoplasmic protein that attaches to exoskeleton

Apodeme

Thread like connection to cuticle

Arthropod muscle innervation

Multiterminal innervation or multineuronal

Multiterminal innervations

Innervation of a single muscle fiber at multiple points

Multineuronal innervations

Innervation of a single muscle fiber by multiple neurons

Excitatory motor neuron NT

Glutamate

Inhibitory moto neuron NT

GABA

Annelid movement

Head is extended forward by contraction of circular muscles, wave of contraction of longitudinal muscles then anchors segments near the head, peristaltic contractions

Caterpillar movement

Looper, roller, crawler; Dorsal longitudinal muscles, verticals muscle, ventral longitudinal muscles

Human gait

Bipedal gait

Arthropod Locomotion

6 legs, slow: one at a time, Faster: metachronal gait, running: Tripod Gait

Tripod gait

Left front leg, right middle leg, left hind leg

Central Pattern Generator

Produces a predictable, Rhythmic firing pattern using a set of interconnected neurons found in thoracic ganglia

Simple central pattern generator

Flexor activity inhibits extensor activity and vice versa

Animal locomotion neural circuitry Types

Central pattern generator, reflex circuit, and combined model

Reflex Chain

Activity by one muscle triggers activity of antagonist muscle

Locust jump

Cocking behavior, co-contraction phase, and trigger phase

Cocking behavior

Tibia fully flexed, brought next to femur, needs arousing stimulus, followed by short pause

Co-contraction phase

Both extensor and flexor muscle contract, no movement, energy stored

Trigger phase

Abruptly relaxes flexor muscle, extensor muscle is free, jump occurs

Steps of flying forward

Downstroke Flip, upstroke, second flip

2 set of wings: wing beat cycle

Hindwing precedes forewing

Direct flight muscles

Muscles directly attached to wings, fine control, synchronous muscle

Indirect flight muscles

Muscles not attached to interior of thorax, thorax changes shape, energy is conserved, asynchronous muscles

Synchronous flight

1:1 neural impulse: muscle contraction, Ca level threshold

Asynchronous flight

Not 1:1 continuous elevated Ca levels, click mechanism, myogenic activity

Click mechanism

Wings are stable when up or down, passing through intermediate unstable position results in a click point

Cockroach flight

Indirect (upstroke) and direct muscles (downstroke)

Fly halteres

Club that oscillates up a down on a hinged joint anti-phase to wing beats, functions as gyroscope, maintains directions during flight

Autocrine signaling

Cell responds to its own signal, Ex: auto inhibition of NE release by NE

Paracrine signaling

Signaling to Neighboring cells, Ex: inflammation

Endocrine signalling

Signals via circulatory system

Endocrine cell

Increase in Intracellular Ca due to stimulus results in Exocytosis of secretory material

Neurosecretory neuron

AP results in increase of Intracellular Ca and exocytosis of secretory material near capillary

2 types of glands

Exocrine and Endocrine

Exocrine gland

Release of material via duct; water, enzymes, ions

Endocrine glands

Ductless, release of hormones directly into blood

Major hormones

Amines, Prostaglandins, Steroids, and Peptides

Peptide/ Protein Hormones

Water soluble, Preprohormone is product

Preprohormone

Converted to prohormone in ER and into active hormone after passing through Golgi

Steroid hormone

Derived from cholesterol, lipid soluable

Classes of steroid hormone

Glucocorticoid, mineralocorticoid, Androgen, Estrogen, progestin

Production and transport of steroid hormone

Carried in globulins, product in mitochondria and smooth ER

Amine hormone

Can be tyrosine derived, tryptophan derived, or histidine derived

Tyrosine derived amine hormones

Catecholamines and thyroid hormones

Catecholamines

Dopamine, Norepinephrine, epinephrine

Thyroid hormones

Iodine, Thyroxine(T4), Triiodthyronine(T3)

Tryptophan derived amine hormones

Serotonin and melatonin

Histidine derived amine hormone

Histamine

Eicosanoids

Derived from polyunsaturated fatty acids, such as Arachidonic Acid , produced in all cells except RBC, active for only a few seconds

Main groups of Eicosanoids

Prostaglandins, Prostacyclins, leukotrienes, Thromboxanes

Prostaglandins

Local chemical mediators, may exert antagonist effects, promote smooth muscle contraction and relaxation, promote clothing, promote inflammation, ovulation, inhibits gastric secretion

Inhibiton of prostaglandin

COX1 inhibitors and COX2 inhibitors

COX 1 inhibitors

Aspirin and Ibuprofen, may cause gastric bleeding, kidney problems, and less blood clotting

COX 2 inhibitors

Celebrate and Vioxx, may cause stroke and heart attack

Hormone affect their target cell by

Inducing increase in production, stimulate or inhibit protein synthesis, modification in proteins, cytoplasm or cell shape

Hormone mechanism

Lipid soluble or water soluble

Lipid soluble

Trigger responses after entering trarget cell; Located in nuclear membrane, cytoplasm or nucleus, slower response

Water soluble

Trigger responses without ever entering target cells, G protein coupling, faster response

Four classes of second messengers

Cyclic nucleotides, DAG, IP3, Calcium ion

Calmodulin

Regulates enzyme activity in target cell, binds to Ca

Receptor cell specificity

Not all cell express the same rectors and cells with same receptors may respond differently based on: cell type, signalling cascade, other simultaneous signals

Biochemical amplification

Utilizing an enzymes to increase a reaction that creates another enzyzme

Termination of Hormone Action

Metabolic Clearance rate and hormone inactivation by target cells

Hormone inactivation

Receptor alteration and removal of receptor hormone complex by endocytosis and degradation: proteins and amine hormones

Hormone regulation is most commonly

Native feeeback

Substrate-Hormone Control

As Gluclose increases it stimulate pancreas to secrete insulin

Multiple receptor Pathways

Convergent or Divergent

Master Glands

Hypothalamus and Pituitary. Stimulate many other endocrine glands to release their hormones

Tropic hormones

Hormones that have other endocrine glands as targets

Anterior Pituitary pathway

Hypothalamus → anterior pituitary → 2nd target → ultimate target

Posterior pituitary pathway

Hypothalamus → posterior pathway → ultimate targets

Neural connection pathway

Hypothalamus → adrenal medulla →epinephrine to target