Study guide

Chapter 5 Lecture Outline The Central Nervous System

Nervous System

Divisions of the nervous system

  1. Central Nervous System- Includes the brain and spinal cord
  2. Peripheral Nervous System- Includes nerves found through the rest of the body

The Somatic Nervous System is NOT involved in controlling smooth muscle function.

There are 4 main functions of the nervous system

  1. Respond to Stimuli (ex: touch or chemical response)
  2. Conduct electrical impulses
  3. Release chemical regulators
  4. Enable perception of sensory stimuli, learning, memory, and control of muscles and glands.

Neurons

Three functional classes of neurons

  1. Afferent Neurons-Responsible for sending information towards the CNS (AKA Sensory Neurons)
  2. Efferent Neurons-Responsible for sending information away from CNS
  3. Interneurons-Found in spinal cord or found in the brain.

Reflexes

Definition: Rapid, involuntary reactions of muscles or glands to a stimulus. There are 2 main types of reflexes

Two main types of reflexes:

  1. Somatic Reflexes: Reflexes involving the skeletal muscles. (Voluntary)
  2. Visceral Reflexes: Reflexes involving the autonomic nervous system. (Ex: organ digestive system. Gagging swallowing)

Reflex arc: Neural pathway involved in accomplishing reflex activity.

Parts of the reflex arc:

1)-Receptor (Detects)2)-Sensory Neuron (Afferent pathway) 3)-Integration Center (Control Center) 4)-Motor Neuron (Efferent pathway) 5)-Effector (Muscle or a gland final response)

The integrating Center is associated with interneurons in the reflex arc.

Two kinds of somatic reflexes:

  1. Monosynaptic Reflex: Simplest reflex, sensory axons synapse directly on motor neurons, no interneurons. (One synapse)
  2. Polysynaptic Reflex: More complex, multiples synapses with interneurons. Longer delay

Glial Cells- AKA neuroglia, are found throughout the CNS. They have 2 important characteristics.

Characteristics

  1. Do not initiate or conduct nerve impulses
  2. Serve as a connective tissue of the Central Nervous System.

There are 4 types of glial cells

  1. Astrocytes
  2. Oligodendrocytes
  3. Microglia
  4. Ependymal Cells

Astrocytes Function: Most abundant glial cell

  1. Holds neurons together
  2. Guides neurons during development
  3. Helps establish BBB (Blood Brain Barrier)
  4. Brain injury repair
  5. Play a role in neurotransmitter activity
  6. Take up excess K+ from brain ECF
  7. Enhance/modify synaptic transmission

Oligodendrocytes Function: Form myelin sheaths in the Central Nervous System Microglia Function: Act as immune defense cells of the CNS Ependymal cells: Line the internal, fluid filled cavities of the CNS Function: Help form cerebrospinal fluid

Protection of the CNS

The CNS is protected by:

  1. Bones
  2. Meninges
  3. Glial Cells
  4. Cerebral spinal fluid
  5. Blood brain barrier

Ventricles: Continuous cavities within the brain. Filled with cerebral spinal fluid (CSF)

CSF has 3 Functions:

  1. Buoyancy (Support 95% of the brain allows it to float)
  2. Protection (Cushion)
  3. Environmental Stability (Transporting of nutrients and chemicals)

Blood Brain Barrier: The blood brain barrier (BBB) protects brain from general circulation by strictly regulating what substances can enter the interstitial fluid of the brain.

Four main functions of the BBB:

  1. Protects the brain from chemical fluctuations in the blood
  2. Minimizes harmful blood-borne substances from reaching the CNS
  3. Prevents hormones that could act as neurotransmitters from reaching the brain 4)Limits the use of drugs for treatment of brain and spinal cord disorders.

Cerebrospinal fluid is found within the ventricles of the brain.

CNS Structures

Four main components of the brain:

  1. Cerebrum (Most complex mental processing, consciousness, awareness of self, personality, language)

Contains: Cerebral Cortex and Basal Nuclei

  1. Diencephalon (Processing relaying sensory information, emotions, day/night cycle)

Contains: Epithalamus, Thalamus, Hypothalamus

  1. Cerebellum (Coordinating Movement)
  2. Brain Stem (Respiratory, Cardiac Center)

Cerebral Cortex The Cerebral cortex is composed mostly of Cell bodies of neurons.

Cerebral cortex is the thin, outer shell of gray matter that covers each hemisphere. Divided into different areas based on:

  1. Location
  2. Function

Cerebral cortex lobes- The hemispheres are divided into 4 major lobes

  1. Frontal lobe
  2. Parietal lobe
  3. Temporal lobe
  4. Occipital lobe
  5. Insula- (Deep to the Temporal lobe- Responsible for processing taste.)

Cerebral cortex-Lobes Frontal Lobe-Has 3 main functions

  1. Voluntary motor activity
  2. Physical speaking
  3. Elaboration of thought (Personality and Decision making)

Phineas Gage/Frontal Lobotomy-railroad worker, after the accident he become rude and couldn’t make decisions.

Parietal Lobe: Receives and processes somatosensory input. (Somatosensory- touch, heat, cold, pain)

Temporal Lobe: Auditory and olfactory sensation (hearing and smell)

Occipital Lobe: Processing visual input (vision processed)

Cerebral cortex of the brain gives us higher intellectual reasoning like consciousness and language.

Cerebral Cortex-Functions

The Cerebral cortex is also organized functionally into 3 main areas

  1. Sensory areas (touch, vision, taste, smell)
  2. Motor Areas (movement)
  3. Association areas (Higher functioning make sense of it put into context)

Sensory areas There are 5 sensory areas in the cerebral cortex:

  1. Primary Somatosensory cortex (Sense of touch)

Location: Parietal Lobe

  1. Primary visual cortex
              Location: Occipital lobe

  1. Primary Auditory cortex

    Location: Temporal Lobe

  2. Primary olfactory cortex

              Location: Temporal Lobe
  1. Primary gustatory cortex
            Location: Insula

Primary Somatosensory cortex

Location: Postcentral gyrus in the parietal lobes Function: Touch, Pressure, Pain, Temperature Receptive Field: The region surrounding a sensory neuron. • The smaller the receptive field the larger the representation area in the primary somatosensory cortex. • The smaller the receptive field in a region the greater the density of the sensory receptors in the region and the smaller the representative are in the primary somatosensory cortex. Sensory area dysfunction: What happens when something goes wrong in one of these areas? Phantom pain-perception of pain from an amputated limb

Motor areas There are 4 main motor areas in the frontal lobe:

  1. Primary Motor Cortex (controlling voluntary movement) Location: Precentral gyrus, controls voluntary muscle movement Controls: Somatic, Skeletal muscles Motor homunculus: Shows location and amount of the motor cortex devoted to each muscle.
  2. Supplementary motor area (coordinating movement)
  3. Frontal eye field (controlling voluntary movement)
  4. Motor speech area (Broca’s area) (Physical ability to speak) (left side controls muscle movement)

Motor area dysfunction

Association Areas-Responsible for the higher functions and bringing together multiple forms of stimuli.

There are 7 main association areas:

  1. Prefrontal-personality, decision making
  2. Premotor-prepares for movement (Frontal lobe)
  3. Somatosensory-interprets sensations
  4. Auditory- interprets sound
  5. Visual- gives meaning to what we see
  6. Wernicke’s area-understanding language
  7. Gnostic area-integrates all sensory, visual, and auditory info

Parietal lobe is the area of the brain that would be involved in processing the sensation of touch. Association area applications/dysfunction

• Facial blindness

Language- Broca’s and Wernicke’s area work together to help us understand and produce language.

Three types of language disorders

  1. Aphasias
  2. Speech impediments (Ex: Stuttering)
  3. Dyslexia

Steps involved in speaking about something heard or seen:

EEG Waves- An electroencephalogram (EEG) detects electrical activity within the cerebral cortex. EEG’s have 3 major uses. Major uses:

  1. Clinical tool in diagnosis of cerebral dysfunction
  2. Used to distinguish various stages of sleep
  3. Used in legal determination of brain death

Basal Nuclei: Masses of gray matter deep within white matter Primary function

  1. Influence muscle movement
  2. Suppresses unwanted movement
  3. Coordinates slow, sustained contractions (Ex: Posture, swinging arms)

Basal nuclei dysfunction- Parkinsonians Disease

Chapter 5&7 Lecture Outline The CNS Cont. and ANS

Central Nervous System

Diencephalon (Middle of the brain) The diencephalon is the second major component of the brain. It contains:

  1. Epithalamus
  2. Thalamus
  3. Hypothalamus

Epithalamus includes:

  1. Pineal gland-secretes melatonin. Determines out day and night schedules.

Thalamus Functions:

  1. “Relay station” for all sensory information
  2. Helps direct attention to stimuli of interest
  3. Crude awareness of a carious types of sensation

Hypothalamus- Directly regulates the internal environment maintain homeostasis

7 Major functions of the hypothalamus:
  1. Control of the autonomic nervous system
  2. Control the anterior pituitary hormone secretion
  3. Control of body temperature
  4. Control of emotion behavior
  5. Control of hunger/food intake
  6. Control of thirst/water intake
  7. Production of posterior pituitary hormones

Quiz Question/Answer:

Q: Melatonin is an over-the- counter supplement that is widely available. What do you think melatonin would be used for? A: Sleep Q: The hypothalamus is a connection between the ________ system and the __________ system. A: Endocrine; Nervous Q: What is the Thalamus function? A: Performs preliminary processing of all sensory input on its way to the cortex.

Cerebellum (Mini Brain) The cerebellum is the third major component of the brain.

Function: 2nd largest area of the brain. Important in balance and in planning and executing voluntary movement

Steps involved:

  1. Motor areas of cortex send information to cerebellum
  2. At the same time sensory information is sent to cerebellum
  3. Cerebellum decides best way to coordinate muscle movement
  4. Movement “blueprint sent to motor cortex

Brain Stem (oldest region of the brain and most evolutionarily conserved region of the brain) The brain stem is the fourth major component of the brain.

Major function of the brain stem:
    Critical connecting link between spinal cord and higher brain regions composed of three regions

Composed of three regions:

  1. Midbrain Function: Contains visual and auditory reflex centers
  2. Pons Function: Regulates breathing.
  3. Medulla Oblongata 4 Main Functions:
  4. Cardiac Center
  5. Vasomotor Center
  6. Medullary respiratory center
  7. Autoionic reflexes Quiz Question/Answer

Q: Which of the following statements regarding the brain stem is incorrect? A: The brain stem controls the processing of emotions and turning it into a physical response.

Reticular Activation System

3 Main Functions of the RAS:
  1. Alerts the cerebrum to incoming sensory information
  2. Processes visual auditory and touch stimuli
  3. Rouses us from sleep

3 Levels of alertness:

  1. Alert
  2. Awake
  3. Sleep Limbic System- A ring of forebrain structure that surrounds the brain stem

Limbic System functions:

  1. Emotions
  2. Socio-sexual behavior
  3. Motivation
  4. Learning

Learning and Memory

Learning Definition: Acquisition of knowledge or skills from experience and /or instruction

Memory Definition: Storage of acquired knowledge for later recall

Memory: Memory trace: The neural change responsible for retention or storage of knowledge

We have two kinds of memory: Short-term and Long-term

Basic characteristics of each:

Short Term Memory Long Term Memory Retained for seconds to hours Retained for days to years Limited capacity Very large capacity Rapid retrieval Slower retrieval Occurs through transient modifications of preexisting synapses Occurs through permanent changes between existing neurons

Short-term memory Mechanisms:

  1. Habituation Definitions: Learning to ignore insignificant stimuli
  2. Sensitization Definitions: Increased response to a repeated stimulus OR to a mild stimulus following a strong stimulus

Long-term memory Categories:

  1. Non-declarative: Implicit memory. Memory of simple skills, how to do things. (How memories? Ex: dance routine, riding a bike)
  2. Declarative: Explicit memory. Memory of things that can be verbalized. Can be further broken down into: (Ex: What? People, places, events, facts)

A. Semantic: Facts B. Episodic: Events

Consolidation: The conversion of short-term memories into long-term memories Factors that can influence transfer:

  1. Emotions
  2. Rehearsal
  3. Association
  4. Automatic memory

Quiz Question/Answer

Q: What type of memory involves a decrease in neurotransmitter release from the presynaptic neuron? A: Habituation

Sleep

Two categories of sleep:
  1. Slow-Wave Sleep: (60-80 mins) Also known as resting sleep, divided into four stages determined by EEG waves.
  2. Paradoxical Sleep:(10 mins) Rapid eye movement (REM) the state during which dreams occur (no muscle movement prevent acting out our dreams)

Quiz Question/ Answer

Q: True or False? REM is also called paradoxical sleep A: True Automatic Nervous System (ANS) Peripheral Nervous System Divisions of the PNS

  1. Autonomic Nervous System (ANS)
  2. Somatic Nervous System

Somatic Efferent Pathway Characteristics: CNS to Skeletal Muscle (Controlled Motor cortex) Autonomic Efferent Pathway Characteristics: CNS to cardiac muscle, smooth muscle, or glands (Controlled by Hypothalamus/Brain stem)

Autonomic Nervous System (ANS) Two neurons in the pathway:

  1. Preganglionic Fiber
  2. Postganglionic Fiber Two neurotransmitters released by neurons in the ANS:
  3. Acetylcholine
  4. Norepinephrine ANS Receptors Two types of ANS receptors: Tissues innervated by the ANS have one or more of several different receptor types for chemical messengers
  5. Cholinergic Receptors--->Bind to ACh
  6. Adrenergic Receptors--->Bind to NE (E)

Cholinergic Receptors Two types of cholinergic receptors that bind to ACh

  1. Nicotinic Receptors: Found on postganglionic cell bodies of all autonomic ganglia
  2. Muscarinic Receptors: Found on effector cell membranes Cholinergic Receptors Receptor Type Neurotransmitter Affinity Effectors with this Receptor Type Effect on Effector Nicotinic Ach from ANS preganglionic fibers All autonomic postganglionic cell bodies Excitatory Muscarinic ACh from parasympathetic postganglionic fibers Cardiac muscle, smooth muscle, some glands Excitatory or inhibitory

Adrenergic Receptors: Binds to norepinephrine and epinephrine

  1. Alpha (a) receptors
  2. Beta (B) receptors ANS Divisions: There are two divisions of the ANS. These differ both anatomically and functionally
  3. Sympathetic System (Fight or Flight)
  4. Parasympathetic System (Rest or Digest)

Characteristics Sympathetic Parasympathetic Spinal cord origins Thoracic and Lumbar Cranial and Sacral Preganglionic fiber length Short Long Postganglionic fiber length Long Short Preganglionic neurotransmitter ACh ACh Postganglionic receptor Nicotinic Receptors Nicotinic Receptors Postganglionic receptor NE ACH Effector Receptor a1, a2, B1. B2 Receptors Muscarinic Receptors

Drawing of Pathways

ANS Divisions

  1. Sympathetic: Dominates in emergency or stressful situations. Promotes responses that prepare the body for strenuous physical activity. (Fight or Flight)
  2. Parasympathetic: Dominates in quiet, relaxed situations. Promotes body-maintenance activities. (Rest and Digest)

ANS Effects Organ Sympathetic Stimulation Parasympathetic Stimulation Heart Increases heart rate/force Decreases heart rate/force Blood Vessels* Constricts N/A Lungs Dilates the bronchioles Constricts the bronchioles Digestive Tract Decreases motility, inhibits digestive secretions Increases motility, stimulates digestive secretions Urinary Bladder Relaxes Contracts (emptying) Eye Dilates the pupil Constricts the pupil Liver (glycogen) Glycogenolysis (glucose is released) None Adipose Cell (fat) Lipolysis (fatty acids are released) None

Quiz Question/Answer

Q: Which of the following occurs with sympathetic stimulation? A: Bronchioles dilate

Adrenal Medulla: The adrenal medulla is a modified part of the sympathetic nervous system. Characteristics:

  1. Preganglionic fiber only
  2. Stimulation of preganglionic fiber releases E and NE into blood

Agonists: Bind to the same receptor as the neurotransmitter and elicits and effect that mimics that of the neurotransmitter Antagonists: Bind with a receptor and block the neurotransmitter’s response

Control of the ANS Four Regions of the CNS that control ANS:

  1. Prefrontal association complex
  2. Hypothalamus
  3. Medulla
  4. Spinal Cord Quiz Question/Answer

Q: True or False? The adrenal medulla is a modified part of the parasympathetic nervous system A: False

Chapter 17 Lecture Outline The Endocrine System

Endocrine System: Consists of ductless endocrine glands scattered throughout the body

Endocrine gland: Pituitary gland, pineal gland, thyroid gland, parathyroid glands, adrenal glands Neuroendocrine gland: Hypothalamus Organs with endocrine tissue: Pancreas, thymus, skin, heart, liver, stomach, small intestine, kidney, adipose tissue, gonads

Main functions of the endocrine system:

  1. Regulate metabolism
  2. Regulate H2O and electrolyte balance
  3. Help the body cope with stress
  4. Promote sequential growth
  5. Control reproduction
  6. Regulate RBC production

Summary of hormone action: • Endocrine cells release hormone • Hormone enters bloodstream • Binding at receptor site initiates hormonal effects • If no receptor, no binding, and no change in cellular activity

Hormone solubility

  1. Water-soluble hormones • Hydrophilic • Amino acid-base hormones • Act on receptors in the plasma membrane that are coupled to G-proteins
  2. Lipid-soluble hormones: • Lipophilic • Steroid and thyroid hormones • Act on receptors inside the cell Tropic Hormones: Hormones that regulate the production and secretion of other hormones Peptide hormones: Hormones that have a direct effect on target cell by altering activity of proteins

Hypothalamus

Two main endocrine functions of hypothalamus:

  1. Produces two small peptide hormones (Vasopressin and Oxytocin)
  2. Produces “releasing” and inhibiting hormones

Peptide hormones produced by the hypothalamus:

  1. Vasopressin (ADH): Conserves water during urine formation
  2. Stimulates uterine contraction during childbirth and milk ejection during breast-feeding.
  3. \

Releasing hormones produced by hypothalamus:

  1. Thyrotropin- releasing hormone Stimulates release of TSH
  2. Corticotropin-releasing hormone Stimulates release of ACTH
  3. Gonadotropin-releasing hormone Stimulates release of FSH &LH
  4. Growth hormone-releasing hormone Stimulates release of GH
  5. Prolactin-releasing hormone Stimulates release of PRL

Pituitary Gland

Composed of two lobes:

  1. Posterior Pituitary- Neurohypophysis
  2. Anterior Pituitary- Adenohypophysis

Posterior pituitary: Does NOT produce any hormones. Stores and releases tow hormones produced by the hypothalamus

Releases two hormones produced by hypothalamus:

  1. Vasopressin
  2. Oxytocin

Anterior Pituitary-Produces and releases 5 tropic hormones and 1 peptide hormone

Produces/releases the following hormones:
  1. Thyroid-stimulating hormone
  2. Adrenocorticotropic hormone
  3. Follicle-stimulating hormone
  4. Luteinizing hormone
  5. Growth hormone
  6. Prolactin* (Peptide hormone)

Negative feedback between hormones released from hypothalamus, anterior pituitary gland and endocrine organ ------------>

Thyroid stimulating hormone Abbreviation: TSH Stimulated by: TRH Target: Thyroid (thyroid follicular cells) Function: Stimulates release of T3 and T4 from thyroid

Adrenocorticotropic hormone Abbreviation: ACTH Stimulated: CRH Target: Adrenal Cortex Function: Stimulates cortisol secretion (resist stress) Follicle stimulating hormone Abbreviation: FSH Stimulated by: GnRH Target and function (Female): Ovarian follicles-follicular growth and estrogen secretion Target and function (Male): Seminiferous tubules-sperm production

Luteinizing hormone Abbreviation: LH Stimulated by: GnRH Target and Function (Female): Ovarian follicles-ovulation Target and function (Male): Interstitial cells-testosterone secretion

Growth Hormone Abbreviation: GH Stimulated by: GHRH Target: Bone, Liver, and soft tissues Function: Stimulates release of insulin-like growth factors (IGFs). Protein anabolism, growth of bones and soft tissues. Dysfunction: Giantism or Dwarfism (early in childhood development) Acromegaly

Prolactin Abbreviation: PRL Stimulated by: PRH Target: Mammary glands Function: Milk secretion

Anterior Pituitary

Thyroid Gland- Located anterior to the trachea composed of two lobes of endocrine tissue. Produces two hormones:

  1. Thyroid Hormone
  2. Calcitonin

Thyroid hormone: Also know as T3 and T4 Synthesized by: Follicular cells Stimulated by: TSH Effect: Determines base metabolic rate, increases heart rate and force of contraction

Calcitonin: Synthesized by: Parafollicular cells Stimulated by: Elevated blood calcium levels Target: Bone and kidneys Effect: Lowers blood calcium levels inhibiting osteoclasts

Thyroid Gland Dysfunction Primary dysfunction: Failure of the thyroid gland itself Secondary dysfunction: Failure of any other part of the pathway (TRH and/ Or TSH release) Goiter: Enlarged thyroid due to increased TSH

Hypothyroidism: Decreased thyroid hormone Hyperthyroidism: Increased thyroid hormone

Primary hypothyroidism: Decreasing in TH
    Effect on hormone release: Increase in TSH

Goiter? Yes, it will form Secondary hypothyroidism: Decrease in TRH/TSH Effect on hormone release: Decrease in TH Goiter? No Goiter Primary hyperthyroidism: Increase in TH Effect on hormone release: Decrease in TSH Goiter? No Goiter Secondary hyperthyroidism: Increase in TRH/TSH Effect on hormone release: Increase TH Goiter? Goiter Graves’ Disease-Bulging of the eyes Effect on hormone release: Goiter? Yes

Parathyroid Gland Parathyroid hormone Synthesized by: Chief cells Stimulated by: Lower blood calcium levels Target: Bone, small intestine, kidneys Effect: Increases blood calcium

Adrenal Glands-are located superior to each kidney Two regions:

  1. Adrenal Cortex
  2. Adrenal medulla Hormones released by adrenal cortex:
  3. Aldosterone
  4. Cortisol
  5. Androgens (Sex hormones) Hormones released by adrenal medulla:
  6. Epinephrine
  7. Norepinephrine

Pancreas Islets of Langerhans: The endocrine cells of the pancreas B (Beta) cells: Insulin Hormone released and Target of hormone: Stimulus of secretion: Glucose a (Alpha) cell: Glucagon Hormone released and target of hormone: Liver Stimulus for secretion: Decrease in glucose