A&P Lab 2 midterm review

Divisions of Peripheral Nervous System Afferent - Sensory Division: Picks up sensory information and delivers it to the CNS. Efferent - Motor Division: Carries information to muscles and glands. Two Divisions of the Efferent System: Somatic – (VOLUNTARY) carries information from CNS to skeletal muscle Autonomic – (INVOLUNTARY) carries information from CNS to smooth muscle, cardiac muscle, and glands 10-4

NEURON STRUCTURE DENDRITES- multiple short branching processes that extend from the cell body; receive signals from other cells and pass those signals to the cell body CELL BODY (SOMA, PERIKARYON) – centrally located; contains typical organelles and contain Nissl bodies (scattered in the cytoplasm and contain Rough Endoplasmic Reticulum AXON – single extension from the cell body; transmits an action potential to effector

Structures Associated with the Axon 1. Axon Collateral – branch of main axon; assists in cell firing 2. Axon Hillock – connection between the cell body and the axon; exact location where an impulse is generated 3. Nodes of Ranvier – gaps in the myelin shealth of the axon; help spread impulses more effienciently 4. Synaptic End Knob (Bulb) – contains a vesicle which houses a chemical called a neurotransmitter

THE MYELIN SHEATH: Insulating Material for Some Axons The myelin sheath is produced by the Schwann cell and oligodendrocytes There are two determining factors that make up the speed of conduction of an action potential down an axon. First is the diameter, larger diameter = higher conduction velocity and vice versa. Second is the presence, or lack thereof, of the myelin sheath. A myelinated axon conducts a nerve impulse much faster than an unmyelinated axon. Myelin sheaths are comprised of unique proteins (myelins) and phospholipids. Give the axons a white appearance, thus neuron that have axons covered with myelin make up the white matter within the cerebellum and cerebrum

Neuroglial Cells Schwann Cells form myelin around axons in the PNS Oligodendrocytes form myelin around the axons in the CNS Astrocytes regulate fluid composition around the neurons, bind blood vessels to nerves; play a role in the blood brain barrier Microglia phagocytotic in response to inflammation Ependymal Cells play an active role in the formation and circulation of CSF 10-11 Satellite Cells Support ganglia in the PNS

MENINGES Meninges membranes surrounding CNS protect CNS three layers dura mater arachnoid pia mater

The cerebellum acts as a relay center for motor pathways and coordinates skeletal muscle coordination and balance. Pia Mater

Cerebrum Divided into 4 surface lobes and one inner lobe : - Frontal lobes (2) - Parietal lobes (2) - Temporal lobes (2) - Occipital lobes (2) - Insular lobes (2) Has a Right and Left Hemisphere (Brain Lateralization) The hemispheres are connected by the corpus collosum – A white nerve tract that runs transversely and facilitates communication between the cerebral hemispheres.

Structure of Cerebrum Corpus Callosum connects hemispheres Convolutions bumps or gyri Sulci grooves Longitudinal fissure separates hemispheres Transverse fissure separates cerebrum from cerebellum 11-19

Frontal Lobe Parietal Lobe Temporal Lobe Occipital Lobe

Functional Regions of Cerebral Cortex Cerebral Cortex – thin layer of gray matter that constitutes the outermost portion of cerebrum; contains 75% of all neurons in nervous system

Lobes of Cerebrum Frontal Parietal Temporal Occipital Insula

Epithalamus Contains Pineal Gland – secretes melatonin /seratonin in the absense and presence of light to help regulate sleep – wake patterns and assists it the regulation of the bodies rhythms.

Brain Stem Three Parts Midbrain Pons Medulla Oblongata

Pons rounded bulge on underside of brainstem between medulla oblongata and midbrain helps regulate rate and depth of breathing (Pneumotaxic & Apneustic Areas) relays nerve impulses to and from medulla oblongata and cerebellum

Medulla Oblongata enlarged continuation of spinal cord conducts ascending and descending impulses between brain and spinal cord contains cardiac, vasomotor, and respiratory control centers contains various non-vital reflex control centers (coughing, sneezing, vomiting)

Ventricles interconnected cavities within cerebral hemispheres and brain stem continuous with central canal of spinal cord filled with cerebrospinal fluid (CSF) Lateral ventricles Third ventricle Fourth ventricle Cerebral Aqueduct

4 th Ventricle Cerebral Aquaduct

Cerebrospinal Fluid secreted by choroid plexus circulates in ventricles, central canal of spinal cord, and subarachnoid space completely surrounds brain and spinal cord clear liquid nutritive and protective helps maintain stable ion concentrations in CNS

Cranial Nerves I and II Olfactory (I) sensory fibers transmit impulses associated with smell Optic (II) sensory fibers transmit impulses associated with vision

Cranial Nerves III and IV Trochlear (IV) primarily motor motor impulses to muscles that move the eyes Oculomotor (III) primarily motor motor impulses to muscles that raise eyelids move the eyes focus lens adjust light entering eye

Cranial Nerve V Trigeminal (V) mixed opthalmic division sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids maxillary division sensory from upper teeth, upper gum, upper lip, palate, and skin of face mandibular division sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip motor to muscles of mastication and muscles in floor of mouth

Cranial Nerves VI and VII Abducens (VI) primarily motor motor impulses to muscles that move the eyes Facial (VII) mixed proprioception sensory from taste receptors motor to muscles of facial expression, tear glands, and salivary glands

Cranial Nerves VIII and IX Vestibulocochlear (VIII) sensory sensory from equilibrium receptors of ear sensory from hearing receptors Glossopharyngeal (IX) mixed sensory from pharynx, tonsils, tongue, and carotid arteries motor to salivary glands and muscles of pharynx

Cranial Nerve X Vagus (X) mixed somatic motor to muscles of speech and swallowing autonomic motor to viscera of thorax and abdomen sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen

Cranial Nerves XI and XII Accessory (XI) primarily motor motor to muscles of soft palate, pharynx, larynx, neck, and back Hypoglossal (XII) primarily motor motor to muscles of the tongue

Spinal Cord Structure Extends foramen magnum to 2 nd lumbar vertebra

Structure of the Eye Hollow Spheroidal Wall has 3 layers (tunics ): Outer - fibrous tunic Middle - vascular tunic Inner - nervous tunic 12-46

THE EYE: BASIC STRUCTURE Three tunics: (from external to internal): - Sclera (Outer Layer) - Choroid (Middle Layer) - Retina (Inner Layer) Sclera: Fibrocollagenous tissue that is modified anteriorly to form the cornea (transparent). The cornea covers 1/6 of the external eye, the remaining 5/6 is covered by the sclera. Choroid: A highly vascularized connective tissue layer which contains numerous melanocytes anteriorly and is continuous with the iris and ciliary body.

THE CHOROID LAYER The Ciliary Body: - Is attached to the lens via the suspensory ligament. - The ciliary body contains smooth muscle cells. It is the contraction-relaxation of the ciliary muscles that focuses light on the retina via the bending of the lens . - The muscles are attached to the suspensory ligament which is attached to the lens.

THE RETINA : Anteriorly, it contributes to the ciliary body and the sclera Posteriorly, contains the photoreceptors (rods & cones ), a pigmented layer and many nerve cells and glial cells. The rods and cones are mixed throughout the posterior retina. There are more rods (for “night vision”) on the periphery. The highest concentration of cones (color vision ) is in the center of the retina. Fovea centralis – Area in the center of the retina where only cones are present = Where our best color images occur. Each cell contains a pigmented protein which contains retinal (a derivative of Vitamin A).

Visual Receptors RODS-(DIMLIGHT RECEPTORS): Long, thin projections Contain light sensitive pigment called rhodopsin Hundred times more sensitive to light than cones Provide vision in dim light Produce colorless vision Produce outlines of objects CONES-(BRIGHT LIGHT RECEPTORS - COLOR VISION): Short, blunt projections Contain light sensitive pigments called erythrolabe, chlorolabe, and cyanolabe, Provide vision in bright light Produce sharp images Produce color vision 12-60 PHOTORECEPTORS

STRUCTURE OF THE ANTERIOR HUMAN EYE.

Aqueous Humor Fluid in anterior cavity of eye Secreted by epithelium on inner surface of the ciliary body Provides nutrients for the eye Maintains shape of anterior portion of eye Leaves cavity through canal of Sclemm (Glaucoma) 12-54

Ciliary Body Forms internal ring around front of eye Ciliary processes – radiating folds Ciliary muscles – contract and relax to move lens 12-51

Iris Composed of connective tissue and smooth muscle Pupil is a hole in iris Dim light stimulates radial muscles and pupil dilates Bright light stimulates circular muscles and pupil constricts 12-53 The “colored part” of the eye.

Structure of the Ear: Composed of three major regions: - External ear - Middle ear - Inner ear The external ear consists of the pinna (auricle ) and the external auditory canal (meatus ). The middle ear consists of the tympanic membrane (eardrum) and three auditory ossicles (bones). These are the malleus, incus, and stapes (or hammer, anvil and stirrup). The middle ear also consists of the Eustachian (auditory) tube.

Structure Continued: The inner ear consists of the vestibular ( balance) apparatus and the auditory apparatus. The vestibular apparatus – Three semicircular ducts , the utricle and the saccule. The saccule consists of the cochlear duct and the Organ of Corti (the auditory apparatus) The inner ear lies within the portion of the temporal bone known as the osseous labyrinth . The osseous labyrinth contains perilymph (plasma like fluid)

Inner Ear - Components The osseous labyrinth contains the membranous labyrinth which is composed of fluid-filled sacs and ducts: - Semicircular canals - Saccule - Utricle - Cochlear duct - Endolymphatic sac and duct The membranous labyrinth is surrounded by the osseous labyrinth which contains the perilymph (like CSF or plasma, contains sodium). The membranous labyrinth contains specialized epithelial cells for sound perception .

Inner Ear Complex system of labyrinths Osseous labyrinth: bony canal in temporal bone filled with perilymph. Membranous labyrinth: tube within osseous labyrinth filled with endolymph. 12-28

Inner Ear 3 Parts of Labyrinths: Cochlea functions in hearing Semicircular canals function in equilibrium Vestibule functions in equilibrium 12-29

External Ear AURICLE Collects sound waves. EXTERNAL AUDITORY MEATUS Lined with ceruminous glands Carries sound to tympanic membrane Terminates with tympanic membrane. TYMPANIC MEMBRANE Vibrates in response to sound waves. 12-25

Auditory Tube (Eustachian Tube) EUSTACHIAN TUBE Connects middle ear to throat Helps maintain equal pressure on both sides of tympanic membrane Usually closed by valve-like flaps in throat 12-27

So How does sound get to our brain? It is funneled by the acoustics of the pinna into the external meatus (external auditory canal). To the tympanic membrane To the malleus (attached to the eardrum), incus and stapes where the stapes vibrates in the oval window. The ossicles function in amplification of sound. The vibrations on the oval window causes pressure waves in the endolymph & perilymph (fluids of the cochlea). The pressure waves in the endolymph cause vibration of the basilar membrane (a thin membrane extending throughout the length of the cochlea). The basilar membrane is covered with cells with mechanoreceptors known as hair cells.

On the apical border of hair cells, cilia are found. When the basilar membrane moves the cilia make contact with the tectoral membrane (the roof) and the displacement of the cilia (hairs) opens ion channels. This results in NT exocytosis. Dendrites from bipolar auditory afferent neurons are stimulated by this NT, and thus sound vibrations are converted into a nerve impulse.

Balance: The semicircular canals are three tubes filled with endolymph Like the cochlea, they contain hair cells that detect motion, but rather than sound, rotational acceleration is perceived. They are innervated by afferent fibers which transmit the signal to the pons and cerebellum. The u tricle and saccule are two other balance-monitoring organs located in the inner ear. They monitor static equilibrium and linear acceleration.

The Endocrine System - General Facts Body’s Secondary Control System Major function is maintaining homeostasis This is achieved by feedback loops (mostly negative or inhibitory feedback loops). Today, Three endocrine systems are recognized: The General Endocrine System (Thyroid Gland, Adrenal Glands, Parathyroid) The Neuroendocrine System (Hypothalamus, Pituitary) The diffuse endocrine system (endocrine tissue – Thymus, Pancreas, Kidneys, Heart, Skin)

Anterior Pituitary Gland: The APG synthesizes and secretes many protein hormones (non-steroidal) in response to the commands from the hypothalamus ( Controlled by the hypothalamus and the releasing factors): 1.Thyroid Stimulating hormone (TSH) 2. Adrenocorticotropic hormone (ACTH) 3. Follicle Stimulating hormone (FSH) 4. Luteinizing hormone (LH) 5. Prolactin (PRL) 6. Growth hormone (GH) 7. Melanocyte-stimulating hormone (MSH) The TSH, ACTH, FSH, GH and LH hormones are tropic hormones that simulate other endocrine glands. In response, the other endocrine glands produce hormones that affect metabolism. For example, TSH from the pituitary gland stimulates the thyroid gland to produce thyroid hormones. In turn, thyroid hormones inhibit the release of calcium in the blood.

Posterior Pituitary Gland: Does not synthesize any hormones It only stores the hormones that are synthesized in the hypothalamus Neuron cell bodies of the hypothalamus produce two hormones 1. Antidiuretic hormone (ADH) 2. Oxytocin These are transported by axons to the neurohypophysis where they are stored (Herring Bodies). The hormones are released by neurosecretion. The hormones travel down the axons of the hypothalamus and terminate in the PPG where hormones are stored until released (secreted).

Anterior Pituitary Hormones Growth Hormone (GH): stimulates increase in size and rate of body cells enhances movement of amino acids through membranes (increased protein synthesis) promotes growth of long bones secretion stimulated by growth hormone-releasing hormone Prolactin (PRL): sustains milk production after birth amplifies effect of LH in males secretion inhibited by prolactin releasing hormone. 13-17

Anterior Pituitary Hormones Thyroid Stimulating Hormone (TSH): controls secretions of hormones from the thyroid gland controlled by thyrotropin-releasing hormone. Adrenocorticotropic Hormone (ACTH): controls secretions of some hormones of adrenal cortex controlled by corticotropin-releasing hormone. 13-18

Anterior Pituitary Hormones Follicle-Stimulating Hormone (FSH): stimulates development of egg-containing follicles in ovaries stimulates follicular cells to secrete estrogen stimulates production of sperm cells controlled by gonadotropin-releasing hormone. Luteinizing Hormone (LH) promotes secretions of sex hormones stimulates release of egg from ovary promotes growth of long bones controlled by gonadotropin-releasing hormone. 13-19

Posterior Pituitary Hormones Antidiuretic Hormone (ADH): causes kidneys to reduce water excretion in high concentration, raises blood pressure (vasopressin) controlled by hypothalamus in response to changes in blood water concentration and blood volume. Oxytocin (OT): stimulates uterine contractions stimulates mammary glands to release milk controlled by hypothalamus in response to stretch in uterine and vaginal walls and stimulation of breasts. 13-20 REMEMBER, THESE TWO HORMONES ARE SYNTHESIZED IN THE HYPOTHALAMUS, PASSED TO THE NEUROHYPOPHYSIS, WHERE THEY ARE STORED PRIOR TO SECRETION.

Thyroid Gland Hormones Thyroxine (T 4 ) and Triiodothyronine (T 3 ): increases rate of energy release from carbohydrates increases rate of protein synthesis accelerates growth stimulates activity in the nervous system controlled by TSH (From the Anterior Pituitary). Calcitonin: lowers blood calcium and phosphate ion concentrations by inhibiting the release of calcium and phosphate from bones and increases the rate at which the kidney excrete calcium increases rate at which calcium and phosphate are deposited in bones 13-22

Parathyroid Hormone PTH: increases blood calcium levels decreases blood phosphate levels stimulates bone resorption (boen removal) by osteoclasts inhibits osteoblasts stimulates kidneys to retain calcium and excrete phosphate promotes calcium absorption into intestine 13-26 WITH CALCITONIN, PARATHYROID HORMONE HELPS TO REGULATE CALCIUM HOMEOSTASIS .

THE PANCREAS BOTH AN EXOCRINE AND AN ENDOCRINE GLAND

Pancreatic Hormones Glucagon: secreted by alpha cells of pancreatic islets stimulates liver to break down glycogen stimulates liver to convert non-carbohydrates into glucose stimulates break down of fats controlled by blood glucose concentrations Somatostatin: secreted by delta cells of pancreatic islets helps regulate carbohydrates Inhibits the secretions of Alpha and Beta Cells 13-35

Pancreatic Hormones Insulin: secreted by beta cells of pancreatic islets promotes formation of glycogen from glucose inhibits conversion of non-carbohydrates into glucose enhances movement of glucose into adipose and muscle cells decreases blood glucose concentrations promotes transport of amino acids enhances synthesis of proteins and fats controlled by blood glucose concentrations 13-36

Insulin and Glucagon Insulin and glucagon function together to stabilize blood glucose concentrations 13-37

THE ADRENAL GLANDS Lies on the superior pole of the kidney. The adrenal glands, small organs near the kidney . Is subdivided into two glands: - Adrenal Medulla (inside) - Adrenal Cortex (outside) Adrenal Gland

HORMONES OF THE ADRENAL CORTEX ZONA GLOMERULOSA (OUTER LAYER): MINERALOCORTICOIDS: ALDOSTERONE ZONA FASCICULATA (MIDDLE LAYER): GLUCOCORTICOIDS: CORISONE, CORTISOL HYDROCORTISONE, CORTICOSTERONE ZONA RETICULARIS (INNER LAYER): ANDROGENS: TESTOSTERONE.

Adrenal Cortex Hormones Aldosterone: increases blood volume and pressure by promoting conservation of sodium ions and water. 13-31

Adrenal Cortex Hormones Cortisol: decreases protein synthesis increases fatty acid release stimulates glucose synthesis from noncarbohydrates 13-32

HORMONES OF THE ADRENAL MEDULLA EPINEPHRINE (ADRENALIN) NOREPINEPHRINE (NORADRENALIN)

Actions of Steroid Hormones Hormone crosses membranes. Hormone combines with receptor in nucleus Synthesis of mRNA activated mRNA enters cytoplasm to direct synthesis of a new protein 13-8 MECHANISM OF ACTION OF STEROID HORMONES.

Actions of Nonsteroid Hormones Adenylate cyclase activated Hormone binds to receptor on cell membrane ATP converted to cAMP cAMP promotes a series of reactions leading to cellular changes 13-9 MECHANISMS OF ACTION OF NONSTEROID HORMONES.

A&P Lab 2 midterm review

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A&P Lab 2 midterm review