Exam 2 ch 10,12-16

Functions of muscle tissue

•Movement (via skeletal muscle/bone, peristalsis….)

•Open and close passageways (sphincters)

•Maintenance of posture

•Joint stabilization •Heat generation

Contractility

can contract (shorten)

Excitability

electrical impulse can travel along membrane

Extensibility

can be stretched

Elasticity

return to resting state after stretch

features of muscle tissues

•Fiber

•Myofilaments

•Sarcolemma

•Sarcoplasm

•Sarcoplasmic reticulum (SR)

Skeletal muscle features

•Blood vessels  \~1 artery/muscle, several veins

•Nerves  \~1 nerve/muscle

•Connective tissue

•Muscle tissue

Myofibrils

cylindrical organelles, make up 80% of sarcoplasm Made of repeating sarcomeres

Sarcomere

extends from Z disc to Z disc

Myosin heads

at both ends of myosin attach to actin and pull actin across it

Neuromuscular junction (motor end plate)

point where the motor axon and the skeletal muscle meet.  Each fiber is innervated

muscle tissue types

skeleton, cardiac, and smooth

skeletal

voluntary

striated

peripheral nuclei

multinucleated

named skeletal muscles (organs)

Cardiac

involuntary

straited1-2 nuclei

wall of heart (myocardia)

smooth

involuntaryno striationsarrector pili muscleperistalsiswall of hollow organs1 nuclei

fiber

muscle cell

myofilament

thick and thin filaments. Need for contracting

actin

thin

myosin

thick

sarcolemma

cell membrane of a muscle fiber

sarcoplasm

cytoplasm in muscle fiber

sarcoplasm reticulum (SR)

SER, store calcium

myofibril

80% of cell volume. Cylindrical organelles

muscle attachments

origins : least moveableInsertions: more moveableTypes

Direct attachment

collagen fibers so short it appears muscle attached directly to bone

Indirect attachment

tendon (most common), rappel, and aponeurosis

myofibril component

series of sarcomeres

Sarcomere

functional unit of contraction in skeletal muscle. Straited

I band

contains only bisected by z line

H zone

only myosin

A band

entire length og myosin and overlapping parts of actin

Functions of Nervous System

•Monitor changes in environment (sensory input) •Process and interpret (integration) •Response (motor output)

Nervous System

•Made primarily of nervous tissue •Organized into CNS and PNS •CNS (brain and spinal cord) •PNS (receptors, nerves, ganglion, nerve endings)

PNS

Peripheral nervous system (receptor)

muscle

contractionAway from CNS

glands

secretion

sensory

somatic- skinVisceral- visceral organsTowards CNS

Nervous Tissue

•Very cellular •Cells densely packed and tightly intertwined

NT cell types

neurons and supporting cells

Neurons

•Excitable (conduct electrical signal) → neurotransmitter (communicate at synapse) •Long life span •Do not divide •High metabolic rate Need for O2 and glucose

Neuroglial Cells (supporting)

Not excitableDon’t form synopsisDivide

Multipolar Neuron

has more than 2 processes

Neurotransmitters

made in cell body

Axonal Transporter

movement of axons on microtubules (no ribosomes or Golgi)

Nissl

cluster of free ribosomes (only in neuron)

Neurofibril

clumps of neurofilaments (intermediate filaments)

Synaptic vesicles

membranous bubbles that contain neurotransmitters

Axodendritic

axon → dendrite, most common

Axoaxonic

axon → axon

Axosomatic

axon → soma

Nerve fiber

long axon

Multipolar

all motor neuronsall interneuron (entirely in CNS, association, 99%)

Bipolar

sensory → special

Unipolar

general sensorysomaticvisceralsensory (input)motor (output)

Functional Classification of Neurons

Direction of impulseRelated to CNASensory: afferent, towards CNSInterneurons : processing (most common)Motor: efferent, away from CNS

Structural Classification of Neurons

•Classified by number of processes –Multipolar ( most common) –Bipolar –Unipolar (pseudounipolar) –Anaxonic (no axon, found in retina)

Cells in CNS

cell body and processes

Cells in PNS

only cell body

Astrocyte

looks like starMost commonmany varied functions

Microglial

smallestleast commonmacrophage (phagocytosis)Arise from monocyte in blood

Ependymal

lines space or cavity/ventricle that contains CSF (cerebral spinal fluid)

Oligodendrocyte

few processmyelinates axons in CNSform myelin insulate the axon

Astrocyte Function

Provide nutritional supportremove any excess neurotransmittersRegulate ionic environments

Ependymal function

help move and make CSF

Oligodendrocyte Functions

1 oligodendrocyte myelinate part of many different axons

Found in PNS

satellite and Schwann cell

Satellite Cell

surround neuron cell bodies in PNSProvide nutrient support and protection

Schwann Cell

every axon in PNS is associated in some way with a Schwann cellForm myelin in PNSCounterpart to oligodendrocyte in CNS

Myelin

only associated with axons never dendrites or somaincreases rate of nerve impulse/conduction/action potentialform of repeating wraps of cell membrane

One Schwann Cell

can hold up to 20 unmyelinated axonscan myelinate part of one axon

neuron

cell

nerve

collection of axons in PNS

White Matter

axons, most are myelinated which give white color.  Also present are glial cells

Gray matter

neuron cell bodies, dendrites, short unmyelinated axons, neuroglia

Cortex

additional gray matter on the surface in a sheet in the cerebellum and cerebrum. (not seen in the spinal cord)

Brain nuclei \= (basal nuclei \= basal ganglia)

isolated areas of gray matter (spherical, irregular shaped) embedded in the white matter

Ventricles of the brain

- central cavities filled with CSF, lined with ependymal cells - continuous with each other and the central canal of spinal cord -several named (seen in lab): lateral (in past called 1st and 2nd), third, 4th which connects to the central canal of the spinal cord

Brain

complex neural functions (i.e. intelligence, consciousness, instincts)

4 regions of the brain

1.  brain stem includes the midbrain, pons, medulla oblongata 2.  cerebellum 3.  diencephalan includes the thalamus, hypothalamus, epithalamus (pineal gland) 4.  cerebrum

Brain Stem

lies in the posterior cranial fossa of the skull.  It has outer white and inner gray.  The brain nuclei (isolated gray) are located in the white matter

3 regions of brain stem

1. midbrain 2.  pons 3.  medulla oblongata

Functions of the brain stem

1.  produces rigidly programmed, automatic behaviors necessary for our survival 2.  acts as passageway for all fiber tracts running between the cerebrum and spinal cord 3.  10 of the 12 cranial nerves attach to it.  (The cell bodies are located in the gray matter.) 4.  integrates auditory and visual reflexes

Midbrain

has cell bodies for cranial nerves III (occulomotor) and IV (trochlear) for eye movement

Pons

has cell bodies for cranial nerves V (trigeminal-skin of face and chewing muscles), VI (abducens- eye movement), VII (facial- muscles of facial expression)

Medulla oblongata

most caudal it blends with the spinal cord at the level of the foramen magnum

Vital centers of brain stem

heart rate, respiratory, and blood pressure

Thalamus

All input to cerebrum must pass through

Hypothalamus

regulate ANS and control release of hormones from pituitary glands

Epithalamus

make melatonin

Commissural

connects hemisphere to hemisphere. Horizontal

Projection

connects brain and spinal cord

Association

connect parts on some level. Horizontal

somatic motor

voluntary, skeletal muscle

visceral motor

involuntary, cardiac, smooth muscle, glands

conus medullas

end of spinal cord

Classification of Neurons

FunctionStructure

Functions of neurons

SensoryInterneuronMotor

Structures of neurons

multipolarbipolarunipolar

multipolar

Interneurons, motor

bipolar

special senses