BIO 264 Chapter Notes - Chapter 11: Foramen Magnum, Axon Hillock, Axon Terminal

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Central Nervous System

Central Nervous System is composed of the brain and the spinal cord

● Brain is primarily nervous tissue, neurons or nerve cells

● Foramen magnum merges brain and spinal cord which passes via vertebral foramen

Peripheral Nervous System is made up of organs of nervous system

● Nerves consist of axons that bundle together with blood vessels and inside sheath

Functions of the Nervous System

Sensory Functions gather information from internal and external environments

Integrative Functions analyze and interpret incoming sensory info to determine a response

Motor Functions the actions responding to integration

Sensory input is gathered by afferent division of PNS, Motor output is from efferent division

Sensory/Afferent Division

● First detected by sensory receptors

PNS Sensory Division

1. Somatic Sensory Division

a. neurons carry signals from muscle, bones, joints, skin

b. Sensory neurons transmit signals from vision, hearing, taste, smell, balance

2. Visceral Sensory Division

a. Neurons transmit signals from organs

b. Signal carried by cranial and spinal nerves

CNS: neurons integrate sensory input and help form a more complete picture, disregards most

info subconsciously

PNS Motor Division: carries out motor functions of the nervous system

● Effectors are muscle that carry out NS effects

1. Somatic Motor Division: voluntary motor division, transmits signals to skeletal muscles

2. Autonomic Nervous System: carry signals to thoracic and abdominal viscera

a. Regulates secretion from glands, contraction of smooth muscle/cardiac muscle

b. Involuntary motor division

Nervous Tissue

Nervous System organs are made of nervous tissue

- Highly cellular, less ECM

- Neuron sends and receives signals as action potentials

- Amitotic: lose centrioles and cannot regenerate

- Dendrites, cell body, axons

- Neuroglial cell (neuroglia) does not transmit signals, just supportive functions

Myelin Sheath insulates and protects the neurons

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Cell Body: (soma)

● Most metabolically active

● Maintain cytoplasm

● RER and Free ribosomes = protein synthesis

○ Nissl Bodies

● Golgi and nuclei

● Mitochondria: high metabolic demands

● Neurofibrils: filaments bundle together to form them and provide structural support to

dendrites and axon

○ Microtubules transport chemicals between axon and body

Dendrites:

● Short, forked process receiving input from other neurons and transmit as electrical

impulses towards body

● Do not generate or conduct action potentials

● Grow and “prune”

Axon:

● Nerve fiber

● Carry signals towards and away from the body

● Can generate and conduct action potential

● Axon Hillock: what axon arises from

● Axon Collaterals: stem from axons

● Telodendria: branches at the end of axon and collateral, terminate axon terminals or

synaptic knobs

● Axolemma: plasma membrane that envelops

● Axoplasm: cytoplasm

● Do not have protein making organelles (ribosomes/golgi)

● Contain mitochondria, intermediate filaments, vesicles, lysosomes

● Substances travel through axoplasm via flow or axonal transport

Slow Axonal Transport: how proteins move, move away at 1-3 mm/day

Fast Axonal Transport: how vesicles and organelles move, relies on motor proteins using ATP

to move along microtubules

- Retrograde: towards body 200 mm/day

- Anterograde: away 400 mm/day

Regions of Neurons

1. Receptive Region: dendrites and cell body (receive signals)

2. Conducting Region: axon (signals travel)

3. Secretory Region: axon terminals (trigger changes)

Neuron Structure

1. Multipolar: single axon, multiple dendrites, widest variability, most common

2. Bipolar: one axon and one dendrite

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a. Retina, olfactory, nasal

3. Pseudounipolar neurons: one axon, start as bipolar then two processes fuse together

a. Splits into axon (bring info towards body) and central process (to spinal cord)

b. Touch, pressure pain

Neuron Functions

1. Sensory/Afferent: carry information towards the CNS, receiving info from sensory

receptor info to PNS then brain/spinal cord

a. Pseudopolar or bipolar

b. Detect environments

c. Motor coordination (joints and muscles)

2. Interneurons: relay messages within CNS between sensory and motor neurons

a. Majority of neurons

b. multipolar

3. Motor/Efferent: carry information away to muscles and glands, multipolar usually

Nuclei- bundles of neurons

Ganglia- bundles of cell bodies

Tracts- bundled axons in CNS

Nerves- bundled axons in PNS

Neuroglia- “glue” together neurons, and protect them, maintain their environment, and assist in

their proper function

- Fill in gaps when neurons die

CNS Neuroglia:

1. Astrocytes- star-shaped, have central portion and numerous processes, terminate in end

feet

a. Anchor neurons and blood vessels in place, transport their nutrients/gases

b. Regulate extracellular environment of the brain

b.i. Connected by gap junctions

b.ii. Clean up extracellular potassium ions and neurotransmitters

c. Assist in blood-brain barrier

c.i. Ensheath capillaries, form tight junctions

c.ii. Separate blood and ECF

d. Repair damaged brain tissue by dividing rapidly

2. Oligodendrocytes- myelinate axons

3. Microglia- become phagocytes during injury and clean it up

4. Ependymal- line cavities, fluid filled cavities, cerebrospinal fluid

PNS Neuroglia:

1. Schwann Cells: myelin sheath of PNS, unmyelinated axons also have schwann cells

a. Repair damaged axons

2. Satellite Cells: surround bodies of neurons and support them

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Document Summary

Central nervous system is composed of the brain and the spinal cord. Brain is primarily nervous tissue, neurons or nerve cells. Foramen magnum merges brain and spinal cord which passes via vertebral foramen. Peripheral nervous system is made up of organs of nervous system. Nerves consist of axons that bundle together with blood vessels and inside sheath. Sensory functions gather information from internal and external environments. Integrative functions analyze and interpret incoming sensory info to determine a response. Sensory input is gathered by afferent division of pns, motor output is from efferent division. Cns: neurons integrate sensory input and help form a more complete picture, disregards most info subconsciously. Pns motor division: carries out motor functions of the nervous system. Nervous system organs are made of nervous tissue. Neuron sends and receives signals as action potentials. Neuroglial cell (neuroglia) does not transmit signals, just supportive functions. Rer and free ribosomes = protein synthesis.

Related Questions

1. Kidneys help to maintain a proper balance of _________ within the body.

Phosphorous

Chloride

Potassium

Calcium Phosphate

ions

All of the above

2. The nervous system has how many major categories?

3. Which major category of the nervous system contains both the Somatic and the Autonomic divisions?

Central Nervous System

Peripheral Nervous System

Neither of these

Both of these

4. Which organ or structure helps to control the master endocrine gland (pituitary gland)?

The pancreas

The thorax

Peyerâs patches

The hypothalamus

6. This tiny gland is located at the base of the brain and produces the hormone melanin.

Parathyroid

Pituitary

Hypothalamus

Pineal

7. These glands are situated right above the kidneys. The hormones produced by these glands help us to cope with stress.

Thyroid

Parathyroid

Hypothalamus

Adrenals

8. The hormones necessary for the production of sperm are produced in the __________.

Kidneys

Testes

Ovaries

None of the above

9. The bloodstream assists the endocrine organs and structures by:

Removing hormones from the body

Delivering hormones to target cells

Delivering hormones to secretory cells

The bloodstream does not come into contact with endocrine structures or organs
10. The pancreas _____________.

Is a master gland that controls many other glands

Produces progesterone and oestrogen

Is a salivary gland

Regulates blood sugar, aid in digestion

11. The basic function of the endocrine system is ________ in nature.

Digestive

Reproductive

Hormonal

Proximal

13. Urinary tract infections (UTIs) are experienced by many people during their lifetimes. Urinary tract infections can involve any bacterial infection of the urinary system structures; the kidneys, bladder, ureters, or urethra. They are caused by bacteria entering the body through the urethra and traveling upward into the body. Symptoms can range from mild discomfort when urinating to extreme pain and the loss of blood during urination. They occur more frequently in women than men, and are often treated by antibiotics in addition to home remedies, such as drinking more water and drinking cranberry juice.

Based on what you have learned about the cause of urinary tract infections, which of the following precautions would help to prevent reoccurring infections?

Taking pain medication when symptoms occur

Placing a hot pack on the abdomen when symptoms occur

Practicing good hygiene Exercising regularly

14. The nervous system is divided into two major divisions: the Central Nervous System and the Peripheral Nervous System. Those divisions have structures that can be classified as belonging to two different subdivisions: the Somatic and the Autonomic systems. The nervous system can be summarized as a complex system of interconnected nerves and special cells called neurons that are used to transmit information (by means of small electrical impulses). Use the information in the table below to help answer questions about the nervous system. Division Organs & Structures Functions Central Nervous System (CNS) Brain Spinal Cord Nerves This is the bodyâs assessment and communication center. It analyzes the information received from the sensory neurons and responds. Peripheral Nervous System (PNS) Sensory Neurons Ganglia (clusters of neurons) Nerves that connect to one another and to the CNS The sensory neurons react to physical stimuli such as light, sound, heat, and pressure, and transmit that information to the CNS. Subdivisions Description Examples Somatic The Somatic system is comprised of nerves that connect the brain and spinal cord to the muscles of the body and sensory receptors in the skin. Reactions to physical stimuli like heat or light. Using your hand to touch Eating food Autonomic The Autonomic system largely involuntary. This system controls the unconscious functions of the body. Breathing Blood Pressure

Feeling overwhelmed or startled by exposure to very loud noises is likely a reaction to information collected by which subdivision of the nervous system:

Somatic

Autonomic

No answer text provided.

15. The thyroid gland is perhaps the most well-known member of the pancreatic system. Many adults are screened for thyroid problems during routine physical exams. This butterfly shaped gland is found at the base of the neck and releases hormones that affect the bodyâs metabolism (the way the body uses energy). The thyroidâs two main hormones are T3 and T4, and they affect many body functions, including: â¢ Breathing â¢ Heart rate â¢ Central and peripheral nervous systems â¢ Body weight â¢ Muscle strength â¢ Menstrual cycles â¢ Body temperature â¢ Cholesterol levels Two common disorders associated with the thyroid include hyperthyroidism and hypothyroidism. Some of the symptoms associated with these disorders are listed in the table below. Hyperthyroidism (Too many hormones released) Hypothyroidism (Too few hormones released) Anxiety Irritability or moodiness Nervousness, hyperactivity Sweating or sensitivity to high temperatures Hand trembling (shaking) Hair loss Missed or light menstrual periods Trouble sleeping Tiredness and fatigue Difficulty concentrating Dry skin and hair Depression Sensitivity to cold temperature Frequent, heavy periods Joint and muscle pain A patient complains of arthritis-like pain in the joints of her hands, but tests for arthritis come back negative. The doctor then suggests a thyroid function test. The doctor is most likely concerned about:

High levels of T3 and T4 hormones in the body

Low levels of T3 and T4 hormones in the body

No answer text provided.

No answer text provided

rubymule151

#1 Visceral sensory information enters the CNS on afferent fibers within

A) dorsal roots S_2 to S_4.

B) dorsal roots T_1 to L_2.

C) cranial nerves V, VII, IX, and X.

D) both B and C

E) A, B, and C

#2 Which of the following is not a function of the neuroglia?

A) support

B) memory

C) phagocytosis

D) secretion of cerebrospinal fluid

E) maintenance of blood-brain barrier

#3 Mary is in an automobile accident and suffers a spinal cord injury. She has lost feeling in her lower

body. Her doctor tells her that swelling is compressing a portion of her spinal cord. Which part of

her cord is likely to be compressed?

A) the anterior gray commissures

B) the anterior white commissures

C) the anterior gray horns

D) ascending tracts

E) descending tracts

#4 The efferent division of the peripheral nervous system innervates:

A) skeletal muscle cells

B) glandular cells

C) smoothmusdecells

D) heart muscle cells

E) all of the above

#5 Cerebrospinal fluid flows within the

A) pia mater.

B) dura mater.

C) filum terminale.

D) arachnoid mater.

E) subarachnoid space.

#6 A patient develops a tumor of a cranial nerve that leads to difficulty in speaking from a loss of

tongue movement.which cranial nerve is affected?

A) glossopharyngeal

B) vagus

C) spinal accessory

D) hypoglossal

E) trigeminal

#7 Parkinson disease is the result of

A) inadequate production of dopamine by substantia nigra neurons.

B) inadequate production of GABA by neurons in the basal nuclei.

C) weak response of the red nuclei of the mesencephalon.

D) decreased levels of acetylcholine from neurons in the substantia nigra.

E) hyperactivity of the limbic system.

#8 Based on the motor homunculus, which of the followingbody regions has the largest motor units?

A) larynx B) hands C) tongue D) face E) back

#9 If the corpus callosum is surgically cu!

A) conscious decisions are made without regard to sensations from the left side.

B) objects toudred by the left hand can be recognized but not verbally identified.

C) symptoms of the "disconnection syndrome" appear.

D) the two cerebral hemispheres operate independently.

E) all of the above

#10 The flexor reflex

A) moves a limb away from a painful stimulus.

B) is an example of a monosynaptic reflex.

C) prevents a musde from generating damaging tension.

D) usually depends on cranial neurons.

E) prevents a muscle from overstretching.

#11 The subdural space lies between

A) the dura mater and the arachnoid mater.

B) the arachnoid mater and the pia mater.

C) the endosteum and the periosteum.

D) the pia mater and the dura mater.

E) the pia mater and the subarachnoid space.

#12 _____ is a condition resulting from an inflammation of a facial nerve.

A) Cerebral palsy

B) Addison disease

C) Bell palsy

D) any of the

#12 Clusters of RER and free ribosomes in neurons are called

A) microglia.

B) neurofilaments.

C) neurofibrils.

D) Nisslbodies.

E) perikaryon.

#1 Visceral sensory information enters the CNIS on afferent fibers within

A) dorsal roots 52 to 54.

B) dorsal roots T1 to L2.

C) cranial nerves V VIL DC and X.

D) bothB and C

E) a, n, and C

#2 Which of the following is not a function of the neuroglia?

A) support

B) memory

C) phagocytosis

D) secretion of cerebrospinal fluid

E) maintenance of blood-brain barrier

#3 Mary is in an automobile accident and suffers a spinal cord injury. She has lost feeling in her lower

body. Her doctor tells her that swelling is compressing a portion of her spinal cord. Which part of

her cord is likely to be compressed?

A) the anterior gray commissures

B) the anterior white commissures

C) the anterior gray horns

D) ascending tracts

E) descending tracts

#4 The efferent division of the peripheral nervous system innervates:

A) skeletal muscle cells

B) glandular cells

C) smoothmusdecells

D) heart muscle cells

E) all of the above

#5 Cerebrospinal fluid flows within the

A) pia mater.

B) dura mater.

C) filum terminale.

D) arachnoid mater.

E) subarachnoid space.

#6 A patient develops a tumor of a cranial nerve that leads to difficulty in speaking from a loss of

tongue movement. IA/hich cranial nerve is affected?

A) glossopharyngeal

B) vagus

C) spinai accessory

D) hypoglossal

#7 Parkinson disease is the result of

A) inadequate production of dopamine by substantia nigra neurons.

B) inadequate production of GABA by neurons in the basal nuclei.

C) weak response of the red nuclei of the mesencephalon.

D) decreased levels of acetylcholine from neurons in the substantia nigra.

E) hyperactivity of the limbic system.

#8 Based on the motor homunculus, which of the followingbody regions has the largest motor units?

A) larynx B) hands C) tongue D) face E) back

#9 If the corpus callosum is surgically cu!

A) conscious decisions are made without regard to sensations from the left side.

B) objects toudred by the left hand can be recognized but not verbally identified.

C) symptoms of the "disconnection syndrome" appear.

D) the two cerebral hemispheres operate independently.

E) all of the above

#10 The flexor reflex

A) moves a limb away from a painful stimulus.

B) is an example of a monosynaptic reflex.

C) prevents a musde from generating damaging tension.

D) usually depends on cranial neurons.

E) prevents a muscle from overstretching.

#11 The subdural space lies between

A) the dura mater and the arachnoid mater.

B) the arachnoid mater and the pia mater.

C) the endosteum and the periosteum.

D) the pia mater and the dura mater.

E) the pia mater and the subarachnoid space.

#12 _____ is a condition resulting from an inflammation of a facial nerve.

A) Cerebral palsy

B) Addison disease

C) Bell palsy

D) any of the

#12 Clusters of RER and free ribosomes in neurons are called

A) microglia.

B) neurofilaments.

C) neurofibrils.

D) Nisslbodies.

E) perikaryon.

BIO 264 Chapter Notes - Chapter 11: Foramen Magnum, Axon Hillock, Axon Terminal

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