Exam 1 Material

osteo

bone

genic

creation

osteogenic cells

stem cells that differentiate into osteoblasts

Osteoblasts

immature cells that actively produce and secrete bone

osteocytes

mature cells that maintain bone

Osteoclasts

-responsible for resorption (breakdown) of bone

derived from a line of white blood cells

secrete hydrochloric acid and lysosomal enzymes

Compact bone

-dense outer layer of bone

-organized with osteons

Spongy (cancellous) bone

-found within flat bones and within the epiphyses (ends) of long bones

-organized with trabeculae

-red bone marrow is found within the trabeculae of spongy bone

Trabeculae

little beans of bone

Flat bones, short bones, and irregular bones

contain bone marrow within spongy bone but no defined medullary cavity

Osteoporosis

characterized by low bone mass, bone reabsoprtion outpaces bone deposition, occurs in most of women after menopause (secretion of estrogens helps maintain bone density)

Rickets

occurs in children, analogous to osteomalacia, weakened and bowed legs, laformation of the head and ribs (casued by dietary vit D and calcium phopshate deficiency). In adults called Osteomalacia

Osteosarcoma

a form of bone cancer

Clinical consideration

Cancerous tumors can secrete hormones that the normal tissue would not do (paraneoplastic syndrome). When a malignant neoplasm secretes PTH, bones become very thin and break easily. The increase in Ca+2 in the blood can also cause problems.

Cranial bones

formed from eight large bones

Cranial paired bones include

temporal bones

pparietal bones

Cranial unpaired bones include

frontal bone

occipital bone

sphenoid bone

ethmoid bone

Facial unpaired bones

mandible and vomer

Facial paired bones

-maxillae

-zygomatic bones

-nasal bones

-lacrimal bones

-palatine bones

0inferior nasal conchase

cleft palate

failure of fusion of the lateral palatine processes, the nasal septum, and/or median palatine process; surgery required

Multifactorial causes:

increased steroid exposure in fetal life augments the chance of cleft/lip/ palate

• anterior cleft palate

• posterior cleft palate ( more common)

Cleft Lip

failure of fusion of the maxillary and medial nasal processes leading to persistent labial groove (uni. and bilateral), surgery required

Unilateral cleft lip is the most common

congenital malformation of the head

Hyoid bone

Body (anterior)

greater horns (laterally)

lesser horns (upwards)

Nervous system

three overlapping functions

1. sensory receptors monitor changes inside and outside the body

• stimulus

• sensory input

2.processes and interprets sensory input

• integration

3.dicatates a response by activiating effector organs

• motor output

Stimulus

changes detected inside or outside the body

Sensory input

information gathered by receptors

Integration

term for interpreting input

Motor output

is the response

Central Nervous System

composed of the brain and spinal cord

• it is the integrating and command center

• neurons and neuroglical cells

Peripheral Nervous system (PNS)

consists of nervs extending from brain and spinal cord

• cranial nerves

• spinal nerves

• nerons and neuroglical cells

-peripheral nerves link all regions of the body to the CNS

Sensory (afferent)

signals picked up by sensor receptors

• carried by nerve fibers of PNS to the CNS

Motor efferent

signals are carried away from the CNS

• innvervate muscles and glands

functional classification of neurons

according to the direction the nerve impulse travels relative to the CNS

Types of neurons

-sensory

motor

interneurons

Sensory (afferent) neurons

transmit impulses toward the CNS

Motor efferent neurons

carry impulses away from the CNS to effector organs

cell bodies are withi nthe CNS

Interneurons (association neurons)

most are multipolar

lie between motor and sensory neurons

-confied to the CNS

multipolar

posses more than two processes

• numerous dendrites and one axon

• mostly found in CNS

Bipolar

possess two processes

• rare neurons

• found in some special sensory organs

Unipolar

possess on short, single process

• start as bipolar neurons during development

• mostly found in PNS

Astrocytes

-most abundant glial cell type

-sense when neurons release glutamte

-extract blood sugar from capillaries for energy

-take up and release ions to control enviornment around neurons

-involved in synapase formation in developing neural tissue

-produce molecules necessary for neuronal growth BDTF

-propagate calcium signals involved with memory

Microglia

-are the smallest and least abundant glial cell

-phagocytes- the macrophages of the CNS

-engluf invading microorganisms and dead nuerons

-derive from blood cells called monocytes

-migrate to CNS during embryonic and fetal periods

Ependymal cells

-line the central cavity of the spinal cord and brain

-ciliated-help circulate the cerebrospinal fluid

Oligodendrocytes

-have few branches

• wrap their cell processes around axons in CNS to form myelin sheaths

Neuroglia in the CNS

-Astrocytes

-microgila

-ependymal cells

-oligodendrocytes

Neuroglia in the PNS

-Satellite cells

-schwann cells

Satellite cells

surround neuron cell bodies within ganglia

Schwann cells (meurolemmocytes)

surround axons in the PNS

• form myelin sheath around axons of the PNS

organization- nmyelinated

centrally located gray matter

organization- myelinated

externally located white matter

sensory neurons: unmyelinated

axon terminal

sensory neurons- myelinated

axon

interneurons are

entirely unmyelinated

Motor neurons- unmyelinated

dendrites and body

motor neurons myelinated

axon

Motor efferent division sub sections

Somatic nervous system

autonomic nervous system

Somatic nervous system

-somatic motor (voluntary)

-conducts impusles from the CNS to skeletal muscles

Autonomic nervous systen

-visceral motor (involuntary)

-conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands

-Sympathetic. parasympathetic

Sympathetic division

-mobilizes body systems during activity

Parasympathetic division

-conserves energy

-promotes house-keeping functions during rest

brain is classfied into four regions

-brain stem

• midbrain, pons, and medulla

-cerebellum

-diencephalon

-cerebral hemispheres (also known as cerebrum)

The Brain Stem

-includes the

• midbrain

• pons

• medulla oblongata

-General functions

• passageway for all fiber tracts running between the cerebrum and spinal cord

• heavily involved with the innervation of the face and head

  • origin of 10 of the 12 pairs of cranial nerves

• produces automatic behaviors necessary for survival

• integrates auditory and visual reflexes

Brain Stem- Medulla Oblongata

-most of the caudal level of the brain stem

• continuous with the spinal cord

-decussation of the pyramids

• crossing over of motor tracts

-four pairs of cranial nerves attach to the med

• VIII- vestibulocochlear nerve

• IX- glossopharyngeal nerve

• X- vagus nerve

• XII- hypoglossal nerve

The core of the medulla contains

-much of the reticular formation

• network of nerve pathways that influence autonomic functions

-Visceral centers include

• cardiac center

• vasomotor center

• respiratory center

• centers for hiccupping, sneezing, swallowing, and coughing

The brain stem- the Pons

-a bridge between the midbrain and medulla oblongata

-Pons contains the nuclei of cranial nerves

• V-trigeminal nerve

• VI- abducens nerve

• VII- facial nerve

contains motor tracts coming from the cerebral cortex