What does the parasympathetic nervous system do? What does the sympathetic nervous system do? When can they work together?
- Parasympathetic: rest/digest
- Sympathetic: fight/flight
- Together: control of external genitalia; symp: ejaculation, vagina reflex contraction; parasymp: vasodilation, erection
How is the Autonomic Nervous System controlled? How does it function?
- - limbic lobe connections influence hypothalamic function; other controls = cerebral cortex, spinal cord
- *connection to limbic system starts fight/flight response
- - exerts effects through reticular formation
- - coordinates heart activity, blood pressure, body temperature, water balance, endocrine activity
- - mediates emotional states and biological drives
How does the somatic nervous system work?
It innervates skeletal muscle.
To contract muscle cells, it activates motor neurons. Nothing needed for relaxation.
Cerebellum is critical to motor coordination.
Compare muscle spindles and golgi tendon reflexes.
Muscle Stretch: Muscle spindles inform the nervous system of the length of the muscle; uses intrafusal muscles.
Muscle Contraction: Golgi tendons inform the brain of the amount of tension in the muscle and tendons; uses extrafusal muscles.
What are reflexes? What are they for?
- Inborn reflex: a rapid, involuntary, predictable motor response
- Learned reflex: result from practice or repetition
They keep us from having to think through simple things like staying "upright, intact, and alive."
What are the sensory division classifications? (By stimulus type, location, and complexity.)
- Stimulus Type
- - respond to touch, pressure, vibration, and itch
- - respond to changes in temperature
- - respond to light energy
- -respond to chemicals (smell, taste, changes in blood chemistry)
- - respond to pain-causing stimuli
- - extreme temperature, excessive pressure, inflammatory chemicals
- - respond to stimuli arising outside the body
- - respond to stimuli arising in internal viscera and blood vessels
- - respond to stretch in skeletal muscles, tendons, joints, ligaments
- ComplexityComplex receptors
- - associated with special senses (vision, hearing, equilibrium, smell, taste)
- Simple receptors
- - general senses; tactile sensations
- - have unencapsulated (touch receptors, hair follicles) or encapsulated dendritic endings (hairless skin)
What are the different types of spinal cord trauma?
flaccid paralysis = severe damage to the ventral root or ventral horn cells; impulses don't reach muscles, muscles atrophy
spastic paralysis = damage to upper motor neurons of the primary motor cortex; muscles stimulated by reflex activity
loss of voluntary control of muscles due to cross sectioning of the spinal cord (paraplegia, quadriplegia)
What are the four types of brain waves? How are they determined? What affects them? What determines clinical death?
Alpha = awake but relaxed
Beta = awake, mentally alert (concentrating)
Theta = common in children
Delta = deep sleep
Clinical Death = flat EEG
- - change with age, sensory stimuli, brain disease, and chemical state of the body
- - epilepsy => reflection of electrical discharges of groups of brain neurons
- - EEG can be used to detect epileptic lesions, tumors, infections, abscesses, etc.
What is the limbic system?
The limbic system is our emotional brain.
- - amygdala = recognizes angry or fearful expressions, assesses danger, and elicits the fear response
- - cingulate gyrus = play a role in expressing emotions via gestures, resolves mental conflicts
- - puts emotional responses to odors
- - interacts with prefrontal lobes => understanding and awareness of emotions
- - hippocampus and amygdala play a role in memory
What is the hypothalamus' function (7)? How does it relate to the autonomic nervous system?
- 1.) autonomic control center => regulates ANS activity by controlling brain stem and spinal cord activity
- 2.) center for emotional response => in the "heart" of the limbic system; pleasure, fear, rage, biological rhythms and drives
- 3.) body temperature regulation
- 4.) regulation of food intake
- 5.) regulation of water balance and thirst
- 6.) regulation of sleep/wake cycles
- 7.) control of endocrine system functioning => controls release hormones, produces posterior pituitary hormones
What are examples of traumatic brain injuries (5) and degenerative brain disorders (3)?
Concussion = temporary alteration in brain function
Contusion = internal hematoma due to jarring force
Subdural or subarachnoid hemorrhage = bleeding from ruptured vessels; may push brain stem through foramen magnum and cause death
Cerebral edema = swelling of the brain
Cerebrovascular accidents (strokes) = blood circulation is blocked, brain tissue dies
Alzheimer's Disease = progressive degenerative disease resulting in dementia
Parkinson's Disease = degeneration of the dopamine-releasing neurons of the substantia nigra
Huntington's Disease - the huntingtin protein mutates and causes degeneration of the basal nuclei and cerebral cortex
What are the needs of the CNS?
- Blood Supply/Metabolic Needs
- - 20% of oxygen, 50% of glucose from body at rest <= high metabolic rate
- - depends on constant blood flow for energy
- Physical Support
- - Bone
- - Meninges (surrounding connective tissue): dura mater, arachnoid mater, pia mater
- - Blood-brain barrier => helps maintain a stable and selective environment for the brain
- - Cerebrospinal fluid => cushioning and constant environment
What are the structural classifications of neurons?
Multipolar = 1 axon and several dendrites
Bipolar = 1 axon and 1 dendrite
Unipolar (pseudounipolar) = single, short process that has two branches
What are the functional classes of neurons?
1.) Sensory (afferent) = transmit impulses from sensory receptors toward the CNS
2.) Efferent = carry impulses from the CNS to effectors
3.) Interneurons = shuttle signals through CNS pathways; processing info
What neurotransmitters function where?
Acetylcholine is in synapses of both the somatic and autonomic nervous system.
It is joined by norepinephrine and epinephrine in the sympathetic NS.
What are the divisions of the nervous system?
- Nervous System
- I. Central Nervous System
- A. brain and spinal cord
- II. Peripheral Nervous System
- A. Sensory/Afferent Division
- B. Motor/Efferent Division
- a. Somatic Nervous System (Voluntary)
- b. Autonomic Nervous System
- - sympathetic division
- - parasympathetic division
What are the two types of synapses?
- Chemical- release neurotransmitters
- - has axon terminal containing synaptic vesicles and an receptor region
- - nerve impulses aren't transmitted directly, but through unidirectional communication resulting from receptor binding of neurotransmitter molecules
- - excitatory synapses lead to depolarization (positive membrane potential)- inhibitory synapses lead to hyperpolarization (negative membrane potential)
- - always one-directional
- - p.407; children's story!
- - use gap junction and direct ions movement for communication
- - protein channels (connexons) adjacent neurons and allow molecules to flow directly from one to the other
- - bidirectional communication
- - excitation/inhibition at same synapse
- - faster than chemical synapses
What is the difference between grey and white matter?
Grey matter is mostly neuron cell bodies.
White matter is dense collections of myelinated fibers.
What do the nodes of ranvier do?
They separate myelinated portions of the axon to allow for axon collaterals to emerge.
What are the differences between myelin sheaths in the PNS and in the CNS? What are myelin sheaths associated with?
- Myelin sheaths are associated only with axons.They serve to protect and electrically insulate fibers to allow nerve impulses to travel more quickly.
- Both have Nodes of Ranvier.
- PNS Myelin Sheaths
- - formed by Schwann cells
- CNS Myelin Sheaths
- - formed by processes oligodendrocytes
- - no neurilemma
What are the components of a nerve?
- Soma (cell body): contains nucleus and most organelles
- Dendrites: receive incoming info
- Axons: transmit electrical impulses (action potential)
- Axon Hillock: where axon and action potential originate
- Axon Terminal: releases neurotransmitter onto other neuron or effectors organ
What is multiple sclerosis?
- - autoimmune disease- loss of muscular control
- - mylein sheaths in CNS become nonfunctional, cause short-circuiting of nerve impulses
- - treatment: immune system-modifying drugs
What are the important cells in the nervous system?
- Neurons, the excitable cells that transmit electrical
- Neuroglia, the supporting cells
- - astrocytes: participate in information processing in the brain, control the chemical environment, support and brace neurons
- - microglia: phagocytize microorganisms and neuronal debris
- - ependymal cells: permeable barrier between the CNS interstitial fluid from the cerebrospinal fluid
- - oligodendrocytes: form insulating myelin sheaths
- - satellite cells: surround neuron cell bodies in PNS
- - Schwann cells: surround peripheral nerve fibers, form myelin sheaths
What are the inflammatory and degenerative joint conditions?
- - inflammation of a bursa caused by a blow or friction
- - treated with rest and ice
- - inflammation of tendon sheaths
- - treated with rest and ice
- - pain, stiffness, swelling of a joint
- - pain relievers
Common Joint Injuries
- - ligaments are stretched or torn
- - treatment: prompt surgical repair
- Cartilage Tears
- - due to compression and shear stress
- - treatment: surgery
- - occurs when bones are forced out of alignment
What are the synovial joints? What is their functional classification and what's an example?
Plane i.e. intercarpal joint
Hinge i.e. elbow joint
Pivot i.e. proximal radioulnar joint
Condyloid i.e. metacarpophalangeal joint
Saddle i.e. carpometacarpal joint of thumb
Ball and socket i.e. shoulder joint
What are the cartilaginous joints? What is their functional classification and what's an example?
Functional Classification: amphiarthroses
- - epiphyseal plates in children
- - pubic symphysis
What are the fibrous joints? What is their functional classification and what's an example?
Functional Classification: synarthroses
- - ligament between the tibia and fibula
- - tooth/bony alveolar socket
What are the functional classifications of joints?
Synarthroses = immovable
Amphiarthroses = slightly movable
Diarthroses = freely movable
What is the structural classification of joints?
- - bones joined by dense fibrous connective tissue
- - no joint cavity
- - most are synarthrotic (immovable)
- - i.e. sutures, tooth/bony alveolar socket
- - bones united by cartilage
- - no joint cavity
- - i.e. pubic symphysis, intervertebral joints
- - articular cartilage, articular capsule
- - has joint cavity
- - synovial fluid
- - reinforcing ligaments
- - nerves and blood vessels
- - i.e. hip and knee joints
Discuss the function and structure of membranes of bone.
- Periosteum- outer fibrous layer and inner osteogenic layer
- - consists of osteoblasts, -clasts, and -genic cells
- - also provides anchoring points for tendons and ligaments
- - covers trabeculae of spongy bone, lines canals of compact bone
- - contains bone-forming and -destroying cells
What are the developmental aspects of bones?
- infant skull has more bones than adult skull
- some skull bones are unfused
- most long bones are well ossified at birth
- cranium is 1/2 adult size
- arms and legs grow at faster rate than head and trunk
- initial skeleton of cartilage, replaced with bone by osteoblasts
- secondary curvatures appear as child develops
- nearly all bones completely ossified by age 25bone mass decreases starting at 40bone resorption predominates in old age; essentially everything falls apart
What are some of the effects of homeostatic imbalances in bones?
- - calcium salts not deposited
- - Vitamin D deficiency, so treated with addition of Vitamin D
- - bone deformities including pain w/weight and bowed legs
- - bone resorption outpaces bone deposit
- - treatment: calcium, vitamin D, and fluoride supplements, Boniva
- Paget's Disease
- - localized excessive and haphazard bone breakdown
- - bone has high ratio of spongy to compact bone
- - treatment: calcitonin and biphosphonates
How do bone fractures heal?
- 1.) Hematoma forms.
- - blood vessels in the bone break, forming the mass of clotted blood
- 2.) Fibrocartilaginous callus forms.
- - granulation tissue/soft callus forms
- - fibroblasts and osteoblasts begin reforming the bone
- - repair tissue (fibrocartilaginous callus) splints bone
- 3.) Bony callus forms.
- - new bone trabeculae form in fibrocartilaginous callus, gradually convert it to bony callus
- - continues for about 2 months until firm union is formed
- 4.) Bone remodeling occurs.
- - remodeling of bony callus; excess material removed
What are 6 common types of fractures?
commuinuted = bone fragments in three or more pieces
compression = bone is crushed
depressed = broken bone portion is pressed inward
greenstick = breaks incompletely; only on one side, like a green twig
spiral = ragged break occurring when excessive twisting forces are applied
epiphyseal = epiphysis separates from the diaphysis along the epiphyseal plate
How can bone fractures be classified?
- Position of bone ends after fracture:
- - nondisplaced = ends retain normal position
- - displaced = ends of normal alignment
- Completeness of the break:
- - complete = broken all the way through
- - incomplete = not broken all the way through
- Orientation of the break to the long axis of the bone:
- - linear = parallel to long axis of the bone
- - transverse = perpendicular to long axis of the bone
- Whether or not the bone ends penetrate the skin:
- - compound (open) = bone ends penetrate the skin
- - simple (closed) = bone ends do not penetrate the skin
Talk about blood calcium and hormonal control of it.
Calcium is needed for transmission of nerve impulses, muscle contraction, blood coagulation, secretion by glands and nerve cells, cell division.
It's primarily controlled by ParaThyroidHormone:
decreased blood calcium levels => PTH released => PTH stimulates osteoclasts to decrease bone matrix and released more calcium
How does bone resorption work (at a molecular level)?
Osteoclasts secrete lysosomal enzymes and acids. The dissolved material enters interstitial fluid and then blood.
What is needed for proper bone deposit? Why?
Bone deposit is the addition of bone where extra strength is needed or there is an injury.
Vitamin C for Collagen synthesis
Vitamin A for osteoblastic and osteoclastic Activity
Vitamin D for absorption of calcium in intestines and kidneys
Growth hormone stimulates division of cartilage cells in epiphyseal
Male/female sex hormones stimulate ossification of epiphyseal plates, and stop bone lengthening
Physical stress also adds as bone grows along lines of force (to dissipate stress)
What are the two types of bone growth? How do they differ?
Interstitial = increased length of long bones
Appositional = increased thickness and remodeling of long bones by osteoblasts and osteoclasts
How is the epiphyseal plate organized?
- There are four functional zones:
- - proliferation
- - hypertrophic
- - calcification
- - ossification
What is the structure of a long bone?
- - bone ends
- - thin layer of compact bone covering an interior of spongy bone
- - epiphyseal line
- - hyaline cartilage on joint surfaces
- - is a collar of compact bone surrounding marrow cavity
- - marrow cavity has yellow marrow in adults
How do bones respond to mechanical stress?
- Wolff's Law: A bone grows or remodels in response to forces or demands placed upon it.
- Bones are thickest about midway through, where bending stresses are greatest.
What are the types of ossification?
- - develops from fibrous connective tissue membrane
- - osteoblast forms bone all around itself by secreting osteoid, sealing itself into a lacuna and becoming an osteocyte
- - the periosteum and woven bone, later replaced by lamellar bone, form
- - forms flat bones (cranial, clavical, etc.)
- - develops from hyaline cartilage (which must be broken down as ossification proceeds)
- - bone collar forms around cartilage, which is calcified and develops cavities
- - periosteal bud comes into cavities, spongy bone forms
- - epiphyses ossify; hyaline cartilage remains only in epiphyseal plate and articular cartilages
What is bone composed of? What is the difference between its organic and inorganic components?
- Organic- osteoblasts
- - osteoclasts
- - osteocytes
- - add to flexibility and strength
- - hydroxapatites/mineral salts (calcium phosphate crystals)
- - account for hardness, compression resistance
How do bone cells develop?
mesenchymal => preosteoblast => osteoblast => osteocyte
hematopoietic stem cell => macrophage => preosteoclast => osteoclasts
How does it work?
What role do hormones play?
Epiphyseal Plate- creates cartilage which is transformed into bone
break bone down (bone resorption) by pumping out hydrogen ions (making a very acid environment to dissolve the bone)
- Osteoblasts form bone through collagen synthesis and mineralization control
- Osteocytes are part of the cellular-feedback mechanism that directs bone to form in the proper places
- Hormones- growth hormone => stimulates ephiphyseal plate activity
- - thyroid hormone => modulates activity of growth hormone
- - testosterone/estrogen => promotes osteoblast activity, growth spurts; induce epiphyseal plate closure
Classification of Bones by Shape
- - longer than they are wide
- - shaft + two ends
- - includes most of the limb bones!
- - roughly cube shapes
- - wrist and ankle bones
- - sesamoid bones are a specialized type of short bone; forms in a tendon; i.e. patella
- - thin, flattened, a bit curved
- - scapulae, sternum, shoulder blades, ribs, most skull bones
- - don't fit in elsewhere
- - vertebrae, hip bones, sphenoid and ethmoid bones
Haversian/Central Canals: central canal of osteon; allow passage of blood vessels, lymphatic vessels, nerve fibers
Lamella: tube that surrounds central canal; contains collagen fibers that all run in the same direction; adjacent lamella have fibers running in opposite direction
Lacunae: cavities containing osteocytes, connected by canaliculi
Compare spongy bone and compact bone.
- Compact Bone- dense bone
- - contains osteons
- - collagenous protein fibers and mineral deposits of calcium phosphate salts
- Spongy Bone- red bone formation occurs in the spongy bone of the skull, ribs, sternum, vertebrae and in the ends of the long bones
- - trabeculae help resist stress as much as possible; no osteons
- - appears more poorly organized than compact bone
Structure and Function of Intervertebral Discs
- - cushionlike pad made of
- - nucleus pulposus; gelatinous, gives the disc its elasticity
- - anulus fibrosus; surrounds NP, limits NP expansion when spine is compressed; binds successive vertebrae together, resists tension in spine, withstands twisting forces
- Function- shock absorbers
- - help spine flex, extend, bend laterally
What are abnormal curvatures of the spine?
scoliosis (abnormal lateral curve)
Curvatures of the Spine
- Posteriorly Concave Curvatures
- - cervical
- - lumbar
- Posteriorly Convex Curvatures
- - thoracic
- - sacral
What are the functions of paranasal sinuses?
- - lightens the skull
- - warm and moistens the air (through mucus!)
- - enhance resonance of voice
Where is it found?
How does it work?
Where: cartilage of the ear
How: similar to hyaline cartilages, but contain elastic fibers
Where is it found?
How does it work?
Where: Pubic symphysis
How: collagen fibers have great tensile strength
Where is it found?
How it works?
Where: Tip of the nose, costal cartilage of ribs, articular cartilage of a joint, thyroid cartilage, cricoid cartilage
How: provides support, flexibility, and resilience (most abundant)
What are the types of skeletal cartilage?
- 1.) hyaline cartilage
- 2.) fibrocartilage
- 3.) elastic cartilage