Animal Science 214 Test #2

What are the subdivisions of the Nervous System? What do they control?

Central Nervous System

-Center of thought, interpreter of environment, and origin of control over body.

Peripheral Nervous System

-Lines of communication between the CNS and the rest of the body.

What are the two different portions of the Peripheral Nervous system? What do they do?

Sensory (Afferent division)

-Somatic and visceral sensory nerve fibers

-Conducts impulses from receptors to the CNS

Motor (Efferent division)

-Motor nerve fibers

-Conducts impulses from the CNS to skeletal muscles

What are the two different portions of the Motor division? What do they do?

Somatic nervous system

-Somatic motor (Voluntary)

-Conducts impulses from the CNS to skeletal muscles

Autonomic nervous system

-Visceral motor (involuntary)

-Conducts impulses from the CNS to cardiac muscle, smooth muscle, and glands

-Parasympathetic and Sympathetic divisions

What are the parasympathetic and sympathetic divisions in the autonomic nervous system?

Parasympathetic division promotes house keeping functions during rest and conserves energy, while sympathetic division mobilizes body systems during activity.

What are the three types of neural cells? Where are they found? What do they do?

Sensory neurons

-Found in the peripheral nervous system

-Conduct signals from receptors to the CNS

Interneurons

-Found in the central nervous system

-Relay messages to the motor neurons and the neurons in the CNS

Motor Neurons

-Found in the peripheral nervous system

-Conduct signals from the CNS to effectors such as muscles and glands

What are the two classes of cells in the nervous system? What do they do?

Neurons

-Carry electrical signals

Glial Cells (neuroglia)

-Act as nerve glue to provide support and nutrients to neurons

What are the different kinds of glial cells? What do they do?

Astrocytes

-20 to 40 % of neuroglia in CNS

-Provide neurons with support and nutrients

Microglial Cells

-10 to 15 % of neuroglia in CNS

-Act as a macrophage, defending cells by consuming plaque and removing dysfunctional neurons.

Ependymal Cells

-Support cerebrospinal fluid-filled cavities

Oligodendrocytes (CNS)

-Form myelin sheath around nerve fibers

Schwann Cells (PNS)

-Provide insulation to the nervous system and form myelin that surrounds neurons

What are the different parts of the neuron? What do they do?

Dendrites

-receive electrical signal from another neuron or receive a neurotransmitter

Cell Body

-Houses the nucleus, rough ER, and golgi apparatus

-Generates ATP

-Receives signals from the dendrites and corrals it into the axon

Axon Hillock

-space between cell body and axon that decides whether or not the signal is strong enough to be carried down the axon

Axon

-long region that transmits the signal

Axon terminals

-Far end of the axon that interacts with with other dendrites or cell bodies

The centerline of a section of muscle is called _____

M Line

What is the name of the process that starts with binding of Actin and myosin?

Cross Bridge Cycle

What is the name of the enzyme that removes ACH from the synapse?

Acetylcholinesterase

What is the most effective way of getting ATP?

Aerobically

What process does not require the use of ATP?

Flow of K+ out of the axon

What are the phases in a muscle twitch?

-Latent period

-Contraction period

-Relaxation period

What are some ways to change the degree of muscle contraction?

Change in strength and frequency

What happens when you increase the strength of the signal to a muscle?

Number of fibers contracting increases

What does the action potential run through once it is propagated by the sarcolemma?

T-Tubules

What are the three types of muscles?

-Skeletal

-Smooth

-Cardiac

What are the five main characteristics of muscles?

-Contractility

-Elasticity

-Conductivity

-Extensibility

-Excitability

What part of the neuron is the location of neurotransmitter release?

Axon terminal

What are three properties of neurons?

-Excitability

-Conductivity

-Secretion/Transmissability

What are the three types of activations in the nervous system?

-Voltage gated

-Chemical/Ligand

-Mechanically gated

For an action potential to occur, what needs to happen?

A threshold needs to be reached.

What charge should the resting membrane potential have?

Negative.

What channels are open during repolarization?

Slow gated K+ channels, making the cell more negative

What channels are open during depolarization?

Voltage gated Na2+ channels, making the cell more positive

What channels are open during hyperpolarization?

Both potassium and sodium channels are open, Na2+ channels reset

Where are the voltage gated channels located in a myelinated cell?

Nodes of Ranivier

What is an axodentritic synapse?

axon of presynaptic cell interacting with post synaptic dendrites

What is an axosomatic synapse?

Axon of presynaptic cell interacting with post synaptic cell body

What is an axoaxonic synapse?

Axon of presynaptic cell interacting with post synaptic axon

What is the first step of signaling in the synaptic cleft?

Flooding of Ca2+

What are the three ways neurotransmitters are removed from the synaptic cleft?

-Diffusion out

-Reuptake pumps

-Removal by an enzyme

What is the function of inhibitory neurotransmitters? (IPSP)

-Open channels to increase potassium or chloride influx

-Lead to hyperpolarization

-Membrane potential declines

What is the function of excitatory neurotransmitters? (EPSP)

-Open channels to allow sodium to flow in at a higher rate than potassium

-Helps trigger action potential

-Membrane potential increases

-Depolarization

What electrical event occurs when a threshold is reached?

Action potential

What are the steps for sending a synapse?

-Action potential reaches axon terminal

-Calcium enters the axon terminal

-Neurotransmitter is released

-Neurotransmitter binds to receptors on post synaptic cell

-Post synaptic cell depolarizes

What is the difference between relative and absolute refractory periods?

Absolute refractory period will not allow for an action potential to occur during this period of time no matter what, while relative refractory period will allow for it if it is great enough

What does the myelin sheath do?

Insulates axon so electrical impulses move quicker along the axon

What are the functions of the muscle system?

-Produce movement

-Stabalize joints

-Maintain posture and body position

-Generate heat

What are the characteristics of skeletal muscle?

-Voluntary

-Striated

-Multinucleated

What are the characteristics of smooth muscle?

-Involuntary

-Non-striated

-One nuclei

What are the characteristics of cardiac muscle?

-Involuntary

-Striated

-Intercalated discs

-one or two nuclei

What would happen if a muscle became totally depleted of ATP?

Muscle would remain in contractile state because it can't break actin-myosin cross bridges.

What is the latent period?

Time lapse between transmission of action potential down the sarcolemma and the first contraction

What are the three ways ATP regenerates?

-Direct phosphorilation

-anaerobic (glycolysis)

-aerobic

What is the growth by division or addition of cells?

Hyperplasia

What is the growth by cell size?

Hypertrophy

What happens at a low intracellular calcium concentration?

-Tropomyosin blocks active sites on actin

-Muscle fiber is relaxed

What is the order of the cross bridge cycle?

-Cross bridge is formed

-Power stroke

-Cross bridge detachment

-Cocking of myosin head

What are the three types of cartilage?

-Hyaline

-Elastic

-Fibrous (fibrocartilage)

What is Hyaline cartilage?

-Most abundant cartilage

-Found in Joints, sternum, nose

-Important for endochondral ossification (bone lengthening) in all bones except for cranium and clavicles

-Frost like appearance, evenly distributed chondrocytes

What is Elastic cartilage?

-Very stretchy and bendable

-Found in ear and epiglottis

-similair to hyaline but stretchier

What is fibrocartilage?

-Found in knees and vertebrae

-Row of chondrocytes and thick row of collagen

-Deals with impact, doesn't stretch but compresses

What are the functions of the skeletal system?

-Protection

-Support

-Anchorage

-Stores minerals

-Hematopoiesis (red blood cell formation)

-Formation of stem cells in bone marrow

-Fat storage

-Hormone production (Osteocalcin: regulates energy expenditure)

Why are organic compounds like collagen important for bones?

-Tensile strength (ability to absorb pressure)

-Bone becomes brittle without it

Why are inorganic compounds like mineral salts important for bones?

Bone becomes soft, bendable, and flimsy without it

What are the two divisions of the skeletal system?

Axial and Appendicular

What does the appendicular skeleton consist of?

Bones of limbs

What does the axial skeleton consist of?

Skull, ribs, vertical collumn, etc

What are the four types of bone?

-Long

-Short

-Flat

-irregular

What is the structural unit of bone?

Osteon

What type of bone cell is responsible for growth?

Osteoblast

What is wolf's law?

A bone grows or remodels in response to the force or demands placed on it. (More work, stronger bone)

What type of bone cell is responsible for sensing mechanical stress and maintaining the matrix?

Osteocytes

What type of bone cell is a stem cell?

Osteogenic

What type of bone cell lines the bone?

Bone lining cells

What type of bone cell is focused on resorption, is very large, and multinucleated?

Osteoclast

What is bone lengthening?

-Occurs early in life

-Endochondral ossification

-increase in length

What is appositional bone growth?

-Growth in bone diameter/width

-Occurs throughout life

What is bone deposition?

Osteoblasts lay down collagen bone matrix

What is bone resorption?

Osteoclasts break down the bone

What are the hormones that affect bone growth?

-Growth Hormones

-Sex Hormones

-Calcitonin

-Parathyroid Hormone