BIO EXAM 2

muscle tissue

able to stretch, able to shorten, able to respond to stimulus, able to return to original length.

Contractile

Able to become shorter or longer

Elastic

return to original shape

Muscle Cell

muscle fiber

Muscle fibers

contract in response to nervous signal (reflex), pace maker cells (heart), Hormones

Oxycontin

Contraction into labor

skeletal muscle tissue

responsible for voluntary movement

smooth muscle tissue

responsible for involuntary movement

What is a myofilament?

Filament that constitutes myofibrils.

What are the two types of myofilaments?

Actin (thin filament) and myosin (thick filament with heads and tails).

Sacromere

contractile unit of a muscle fiber

uncontracted smooth muscle

contracted smooth muscle

location of smooth muscle

walls of blood vessel, walls of lymphatic vessels, urinary bladder, uterus, GI Tract, iris of eye.

smooth muscle

Involuntary muscle found inside many internal organs of the body

Electrical signals travel through...

cell connected together so that cells function as a unit

What is required for skeletal muscle to contract?

Signal from a neuron

Exitable

Stimulated (Stimilus)

Extensible

capable of being extended/ stretch

cardiac muscle tissue

responsible for contraction of heart

voluntary movement

movement that is under a person's control

involuntary movement

movement that is out of a person's control

cardiac muscle

Involuntary muscle tissue found only in the heart.

Cell Junctions

Adhesion junction keep cells together, gap junctions allo for united contraction.

How do skeletal muscles work in the body?

In pairs of antagonistic muscles

Name some examples of skeletal muscles in the body.

Triceps, biceps, quads, hamstrings

Skeletal "Muscle"

Skeletal muscle tissue, connective tissue, blood tissue, nerves

Muscle Hierarchy

- Muscles
- Fascicles
- Muscle fibers
- Muscle cells
- Myofibrils
- Sarcomeres
- Myofilaments

Tedons

connective tissue, extending from muscle, fascicle + fiber

Polymer (muscle)

Myofibril

Monomer (muscle)

Sarcomere

Muscle Fiber Structure

Cylindrical, long, multi-nucleated inward extensions of cell membrane, carry electrical signal inside, contains myofibrils, strores calcium.

contractile proteins

Myosin filaments (thick,head tails), actin filament (thin)

Actin and myosin overlap from sarcomere

true

The length of the myosin is not decreased when contaction happens

True

z line

Adjacent sarcomeres are attached by joining thin filaments. Filaments DO NOT decrease in length

M line

stationary area where myosin bings to actin and pulls the actin toward the middle of sarcomere

nervous system functions

Senses external stimuli, senses internal stimuli, transmits signals from one organ to another organ, coordinates body activities.

Tissues

Groups of cells with a common structure that work together for a function.

Neurons

Send electrical signals, transmit nerve impulses

gilal cells (gila)

cells in the nervous system that support, nourish, and protect neurons. regulate nutrient/ion concentration.

Blood-brain barrier

Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out. Protects from toxins

Myelin Sheath

Produce cerebrospinal fluid (crushion), scavenge dead cells, pathogen in brain, structural support for synapse, stimulate nerve growth, outnumber neurons 10:1

Astrocytes

form blood brain barrier, Provide structural and metabolic support for neurons.

Glioblastomas

the most aggressive type of primary brain tumor in adults, Uncontrolled growth of Astrocytes.

Glioblastomas life expency

3 months w/out treatment, 12-16 w/ treatment

Why is it difficult to treat Glioblastomas?

Almost impossible to remove entire tumor, many drugs cant cross the blood-brain barrier.

What are microglia?

Immune cells of the CNS

How do microglia differ from other glia?

During embryogenesis, they emerge from the same family of stem cells that become white blood cells

microglia functions

Look for dead cells, toxins, pathogens, etc. Check if neurons are functioning.

Microglia behavior

Can be altered by many factors; stress, depression, autism.

Where do we find the greatest concentration of neurons and gila?

The brain is considered a part of the peripheral nervous system

3 types of neurons

sensory (form senses), motor (muscle), interneurons (brain spinal)

Change in electrical charge (voltage) across a membrane

makes a neuron work

Nerve signal

movement of ions (Na+, K+) across a membrane all the way down a axon.

Structure and Function of Neurons

Neurons are the fundamental units of the nervous system, responsible for transmitting information throughout the body.

Two types of branches extend from the cell body: axons and dendrites

The resting membrane potential

approximately -70 mV, maintained by the distribution of ions (Na+, K+, Cl-) across the membrane.

Depolarization

occurs when sodium ions enter the neuron, leading to a reversal of the intracellular charge, which is crucial for action potential generation

What structures protect the Central Nervous System (CNS)?

Bone (skull and vertebrae), meninges, and cerebrospinal fluid (CSF)

What do the protective structures of the CNS provide?

Physical and chemical barriers

CSF functions

CSF is produced by glial cells and serves multiple functions: nutrient delivery, waste removal, buoyancy, and shock

blood-brain barrier

selectively allows substances to enter the CSF, impacting how drugs like caffeine and alcohol affect brain function.

The brain is divided into

the cerebrum, cerebellum, and brainstem, each responsible for different functions.

cerebrum

Area of the brain responsible for all voluntary activities of the body

cerebellum

A large structure of the hindbrain that controls fine motor skills.

brainstem

The oldest part and central core of the brain, responsible for automatic survival functions. regulates vital functions such as heart rate, breathing, and reflexes

Neuron Communication Mechanisms

Neurons communicate through synapses, where neurotransmitters are released from axon terminals into the synaptic cleft.

What opens in response to an electrical signal?

Calcium channels

What is the role of calcium channels in neurons?

Facilitating neurotransmitter release

Why is neurotransmitter release essential for signal transmission between neurons?

allow the neuron to communicate with other neurons

depolarization

Loss of a state of polarity; loss or reduction of negative membrane potential

hyperpolarization

membrane potential becomes more negative

central nervous system (CNS)

the brain and spinal cord

peripheral nervous system (PNS)

motor and sensory nerves that connect the CNS to the rest of the body.

organization of the nervous system

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

What are the components of a neuron?

Dendrites, cell body, and axon

What is the role of dendrites in a neuron?

Receiving signals

What is the role of the cell body in a neuron?

Processing signals

What is the role of the axon in a neuron?

Transmitting signals

Function of Neurons

process and transmit information

Dendrites receive

incoming signals through gated ion channels

the axon transmits

signals away from the cell body.

Neurons communicate through

synapses

neurotransmitters are released to

transmit signals to other neurons.

resting membrane potential of neuron

-70mV

What ions does the Na+/K+ pump transport?

3 sodium ions out and 2 potassium ions into the cell

How does the Na+/K+ pump contribute to the negative charge inside the neuron?

By actively transporting ions in and out of the cell

A stimulus can cause

gated ion channels to open, leading to depolarization if the inside of the cell becomes more positive (e.g., -60mV).

Excitatory signals

increase the likelihood of an action potential

inhibitory signals

decrease likelihood that neuron will fire

Nerve Impulses

electrochemical changes that neurons use to transmit information

voltage-gated sodium channels open

allowing Na+ ions to rush into the neuron, further depolarizing the membrane.

depolarization travels along the axon

as a nerve impulse, with adjacent segments of the membrane being depolarized in a wave-like manner.

Myelin sheaths

insulate the axon, allowing for faster signal transmission through saltatory conduction.

Inactivated sodium channels

prevent the impulse from traveling backward, ensuring unidirectional flow.

Synaptic Transmission

The relaying of information across the synapse by means of chemical neurotransmitters.

When a nerve impulse reaches the axon terminal

it triggers the opening of voltage-gated Ca2+ channels, allowing calcium ions to enter the neuron.

What is the role of Ca2+ in synaptic transmission?

Ca2+ causes synaptic vesicles to fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.

What happens when Ca2+ enters the presynaptic terminal?

It triggers the fusion of synaptic vesicles with the presynaptic membrane, leading to the release of neurotransmitters into the synaptic cleft.

Neurotransmitters bind to

receptors or chemically-gated ion channels on the postsynaptic neuron, leading to either excitatory or inhibitory effects.