Anatomy Review

Spring 2010

Structural Classification of the Nervous System

• Central nervous system (CNS)– Brain– Spinal cord

• Peripheral nervous system (PNS)– Nerves outside the brain and spinal cord

• Spinal nerves• Cranial nerves

Nervous Tissue: Neurons

Figure 7.4

Transmission of a Signal at Synapses

Figure 7.10, step 7

Axonterminal

Vesicles

Synapticcleft

Actionpotentialarrives

Synapse

Axon oftransmittingneuron

Receivingneuron

Neurotrans-mitter is re-leased intosynaptic cleft

Neurotrans-mitter bindsto receptoron receivingneuron’smembrane

Vesiclefuses withplasmamembrane

Synaptic cleftNeurotransmittermolecules

Ion channels Receiving neuron

Transmitting neuron

Receptor

Neurotransmitter

Na+Na+

Neurotransmitterbroken downand released

Ion channel opens Ion channel closes

• Impulses are able to cross the synapse to another nerve

• Neurotransmitter is released from a nerve’s axon terminal

• The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter

• An action potential is started in the dendrite

Regions of the Brain

• Cerebral hemispheres (cerebrum)• Diencephalon• Brain stem• Cerebellum

Regions of the Brain: Cerebrum

• Specialized areas of the cerebrum – Primary somatic sensory area

• Receives impulses from the body’s sensory receptors• Located in parietal lobe

– Primary motor area • Sends impulses to skeletal muscles• Located in frontal lobe

– Broca’s area• Involved in our ability to speak

• Cerebral areas involved in special senses– Gustatory area (taste)– Visual area– Auditory area– Olfactory area

• Interpretation areas of the cerebrum– Speech/language region– Language comprehension region– General interpretation area

Regions of the Brain: Diencephalon

• Thalamus – The relay station for sensory impulses– Transfers impulses to the correct part of the cortex for localization and

interpretation

• Hypothalamus• Helps regulate body temperature• Controls water balance• Regulates metabolism

• Epithalamus – Houses the pineal body

Regions of the Brain: Brain Stem

• Pons – Includes nuclei involved in the control of breathing

• Medulla Oblongata – Contains important control centers

• Heart rate control• Blood pressure regulation• Breathing• Swallowing• Vomiting

• Midbrain• Reflex centers for vision & hearing

Regions of the Brain: Cerebellum

Figure 7.16aProvides involuntary coordination of body movements

PNS: Autonomic Functioning

• Sympathetic—“fight or flight”– Response to unusual stimulus– Takes over to increase activities– Remember as the “E” division

• Exercise, excitement, emergency, and embarrassment

• Parasympathetic—“housekeeping” activites– Conserves energy– Maintains daily necessary body functions– Remember as the “D” division

• digestion, defecation, and diuresis

Table 7.3 (1 of 2)

Effects of the Sympathetic and Parasympathetic Divisions of the ANS

The Endocrine System

• Uses chemical messengers (hormones) that are released into the blood

• Hormones control several major processes– Reproduction– Growth and development– Mobilization of body defenses– Maintenance of much of homeostasis– Regulation of metabolism

• These hormones regulate the activity of other cells

Location of Major Endrocrine Organs

Figure 9.3

Pituitary Gland

• Often called the “master endocrine gland”• 1. Growth hormone (GH)- disorders

– Pituitary dwarfism results from hyposecretion of GH during childhood– Gigantism results from hypersecretion of GH during childhood– Acromegaly results from hypersecretion of GH during adulthood

2. Prolactin (PRL)

tropic hormones: stimulate other endocrine glands• 3. Thyroid-stimulating hormone(TSH)• 4. Adrenocorticotropic hormone (ACTH)• 5. Two gonadotropic hormones (FSH) (LH)

Hypothalamus– Oxytocin: Stimulates contractions of the uterus during labor, sexual relations, and

breastfeeding & Causes milk ejection in a nursing women

– Antidiuretic hormone: Inhibits urine production by promoting water reabsorption by the kidneys

Thyroid – Thyroid hormone: Major metabolic hormone– Calcitonin: Decreases blood calcium levels causing deposition on

bone

• Parathyroid Glands: parathyroid hormone (PTH)» Raise calcium levels in the blood

Adrenal Glands• Hormones of the Adrenal Cortex (Outer Layer)• 1. Mineralocorticoids (mainly aldosterone)

– Produced in outer adrenal cortex– Regulate mineral content in blood– Regulate water and electrolyte balance– Target organ is the kidney– Production stimulated by renin and aldosterone– Production inhibited by atrial natriuretic peptide (ANP)

• 2. Glucocorticoids (including cortisone and cortisol)– Produced in the middle layer of the adrenal cortex– Promote normal cell metabolism– Help resist long-term stressors– Released in response to increased blood levels of ACTH

Roles of the Hypothalamus and Adrenal Glands in the Stress Response

Figure 9.13, step 13

Short term More prolongedStress

Hypothalamus

Nerve impulses

Adrenalcortex

Releasing hormone

Corticotropic cells ofanterior pituitary

ACTH

Mineralocorticoids Glucocorticoids

1. Retention of sodiumand water by kidneys

2. Increased bloodvolume and bloodpressure

1. Proteins and fatsconverted to glucoseor broken down forenergy

2. Increased bloodsugar

3. Suppression ofimmune system

Long-term stress response

Short-termstress response

Spinal cord

Adrenalmedulla

Preganglionicsympatheticfibers

Catecholamines(epinephrine andnorepinephrine)

1. Increased heart rate2. Increased blood pressure3. Liver converts glycogen to

glucose and releases glucoseto blood

4. Dilation of bronchioles5. Changes in blood flow

patterns, leading to increasedalertness and decreaseddigestive and kidney activity

6. Increased metabolic rate

Male Reproductive SystemTestes :Each lobule contains one to four seminiferous tubules

Tightly coiled structures; Function as sperm-forming factoriesEmpty sperm into the rete testis (first part of the duct system)

Sperm travels through the rete testis to the epididymisInterstitial cells in the seminiferous tubules produce androgens such as testosterone

EpididymisFunctions to mature and store sperm cells (at least 20 days)Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens

Duct deferensCarries sperm from the epididymis to the ejaculatory duct

Ejaculation—smooth muscle in the walls of the ductus deferens create peristaltic waves to squeeze sperm forwardVasectomy—cutting of the ductus deferens at the level of the testes to prevent transportation of sperm

Female Reproductive System

Ovaries : Composed of ovarian follicles (sac-like structures)Each follicle consists of : Oocyte (immature egg) & Follicular cells—surround the oocyte

Duct System: Uterine tubes (fallopian tubes): Receive the ovulated oocyte; Provide a site for fertilization; Attach to the uterusUterus Receives a fertilized egg; Retains the fertilized egg; Nourishes the fertilized eggVagina Serves as the birth canal; Receives the penis during sexual intercourse

Pelvic inflammatory disease (PID) refers to infection of the uterus (womb), fallopian tubes (tubes that carry eggs from the ovaries to the uterus) and other reproductive organs that causes symptoms such as lower abdominal pain. It is a serious complication of some sexually transmitted diseases (STDs), especially chlamydia and gonorrhea. PID can damage the fallopian tubes and tissues in and near the uterus and ovaries. PID can lead to serious consequences including infertility, ectopic pregnancy (a pregnancy in the fallopian tube or elsewhere outside of the womb), abscess formation, and chronic pelvic pain.

Formed Elements of Blood• Erythrocytes

– Red blood cells (RBCs) Wear out in 100 to 120 days

– Main function is to carry oxygen

Hemoglobin: Iron-containing protein– Anemia is a decrease in the oxygen-carrying ability of the blood– Sickle cell anemia (SCA) results from abnormally shaped hemoglobin– Polycythemia is an excessive or abnormal increase in the number of erythrocytes

• Leukocytes – White blood cells (WBCs) Crucial in the body’s defense against disease– These are complete cells, with a nucleus and organelles– Able to move into and out of blood vessels (diapedesis)– Can move by ameboid motion– Can respond to chemicals released by damaged tissues– Leukocytosis: WBC count above 11,000 leukocytes/mm3; Generally indicates an infection

– Leukopenia: Abnormally low leukocyte level; Commonly caused by certain drugs such as corticosteroids and anticancer agents

– Leukemia: Bone marrow becomes cancerous, turns out excess WBC

• Platelets – Cell fragments; Derived from ruptured multinucleate cells (megakaryocytes)– Needed for the clotting process

Blood• Hematopoiesis:

– Blood cell formation– Occurs in red bone marrow

• Undesirable Clotting– Thrombus: A clot in an unbroken blood vessel– Embolus: A thrombus that breaks away and floats freely in the bloodstream;Can later clog vessels in critical areas

such as the brain

• Bleeding Disorders– Thrombocytopenia: Platelet deficiency– Hemophilia: Hereditary bleeding disorder;

• Normal clotting factors are missing

• Human Blood Groups– Antigens (a substance the body recognizes as foreign)

• may be attacked by the immune system

– Antibodies are the “recognizers”