THE NERVOUS SYSTEM BRAIN STRUCTURE AND PHYSIOLOGY
TWO MAJOR DIVISIONS• The Central Nervous System (CNS)• Peripheral Nervous System (PNS)
THE CENTRAL NERVOUS SYSTEMControls the center of the body;• relays messages•processes information•analyzes information
PARTS THAT MAKE UP THE CNS• Cerebrum: largest most prominent region of the human brain (front of the brain). Responsible for the voluntary or conscious, activity of the body. Site of intelligence, learning and judgment.• Cerebellum: second largest region of the brain. Coordinates and balances the actions of the muscles. (back of the brain)• Thalamus: receives messages from all the sensory receptors throughout the body and then relays information to the proper region of the cerebrum for further processing.
THE PERIPHERAL NERVOUS SYSTEM• Nerves stimulate regions of the head and neck, spinal nerves, and ganglia.• It can be divided into the sensory division and the motor division• Sensory division: transmits impulses from sense organs to central nervous system.• Motor division: transmits impulses from the central nervous system to the muscles or glands.
THE NERVOUS SYSTEM : COMMUNICATION•A. Neurons = masses of nerve cells that transmitinformation1. Cell Body - contains the nucleus and two extensions2. Dendrites – shorter, more numerous, receiveinformation3. Axons – single, long “fiber” which conducts impulseaway from the cell body, sends information
HUMAN CIRCULATORY SYSTEM• Systemic Circulation – delivers blood to all body cells and carries away waste• Pulmonary Circulation – eliminates carbon dioxide and oxygenates blood (lung pathway)
STRUCTURE OF THE HEART• Heart Size: (size of a fist) approximately 14 cm x 9 cm• Located in the mediastinum (space between lungs, backbone, sternum), between the 2nd rib and the 5th intercostal space.• The distal end of the heart is called the apex
WALLS OF THE HEART• Epicardium – outer layer, reduces friction• Myocardium – middle layer, mostly cardiac muscle• Endocardium – thin inner lining, within chambers of the heart
HEART CHAMBERS & VALVES• Heart has 4 chambers: • 2 Atria – thin upper chambers that receive blood returning to the heart through veins.. Right and Left Atrium • 2 Ventricles – thick, muscular lower chambers. Receive blood from the atria above them. Force (pump) blood out of the heart through arteries. Right and left ventricle.• Septum – separates the right and left sides of the heart
Valves of the Heart – allow one-way flow of blood• 4 total (2 Atrioventricular • Pulmonary Semilunar, or Valves (AV) & 2 Semilunar just pulmonary valve. valves) Between the left ventricle• Left Atrioventricular valve and the aorta – also called the bicuspid valve or mitral valve. Between left atrium and ventricle• Right Atrioventricular valve – also called the tricuspid valve. Between right atrium and ventricle• Aortic Semilunar – or just aortic valve. Between the left ventricle and the aorta
BLOOD VESSELS•Blood Vessels: arteries, veins, capillaries•ARTERIES : strong elastic vessels which carry bloodmoving away from the heart. Smallest ones arearterioles which connect to capillaries.•VEINS - Thinner, less muscular vessels carrying bloodtoward the heart. •Smallest ones are called venules which connect tocapillaries. Contain valves.
CAPILLARIESPenetrate nearly alltissues. Walls arecomposed of a singlelayer of squamouscells – very thin. Critical function:allows exchange ofmaterials (oxygen,nutrients) betweenblood and tissues.
MAJOR BLOOD VESSELS• Aorta - Ascending Aorta, Aortic Arch, Descending Aorta, Abdominal Aorta. The aorta is the largest artery. (leaves left ventricle) • Pulmonary Trunk – splits into left and right, both lead to the lungs (leaves left ventricle) • Pulmonary Veins – return blood from the lungs to the heart (connects to left atrium)• • Superior and Inferior Vena Cava – return blood from the head and body to the heart (connects to right atrium)
MALE REPRODUCTIVE SYSTEMMajor Structures: testes, vas deferens, prostate, penis
MALE REPRODUCTIVE SYSTEM• Function: Produces and delivers sperm• Parts: scrotum, seminiferous tubules, epididymis, vas deferens, testes, urethra, penis
PARTS• Scrotum: where testes • Vas deferens: the tube remain outside the that carries sperm from body cavity. the epididymis to the Temperature 37°C. urethra.• Seminiferous tubules: • Urethra: tube that located in the testis are carries urine from the clusters of hundreds of bladder and releases it tiny tubules. from the body.• Epididymis: where fully • Penis: contain a matured sperm are tube(urethra) that stored. leads to the outside of• Testes: makes sperms, the body. produces testosterone.
FEMALE REPRODUCTION• OVARY - this is where the eggs are produced through cell division (MEIOSIS)• - each ovary takes turns releasing eggs every month, twins occur if two eggs are released• Ovaries secrete both estrogen and progesterone. • Estrogen is responsible for the appearance of secondary sex characteristics of females • Progesterone regulates menstruation
EMBRYO DEVELOPMENT • An egg is usually a few days old before it implants in the uterus. At this point, it has already divided several times and is called a blastula.
Uterus• The uterus consists of a body and a cervix. The cervix protrudes into the vagina. • The uterus maintains an environment for accepting a fertilized egg. • The fertilized ovum becomes an embryo, attaches to a wall of the uterus, creates a placenta, and develops into a fetus (gestates) until childbirth. • If no fertilized egg reaches the uterus, the lining is shed monthly in a process known as menstruation
REVIEW QUESTIONSQuestions:2. Name the stage of development the embryo is a hollow ball of identical cells:3. Name the part of the female reproductive system the egg cells are released:3. Name the structure specialized for taking blood away from the heart:4. Which part of the brain is responsible for the voluntary or conscious, activity of the body?5. List the four different lobes of the brain:6. which structure transports deoxygenated blood back to the heart?
REVIEW ANSWERSQuestions:1. Name the stage of development the embryo is a hollow ball of identical cells:(blastula)2. Name the part of the female reproductive system the egg cells are released:(ovaries)3. Name the structure specialized for taking blood away from the heart:(arteries)4. Which part of the brain is responsible for the voluntary or conscious, activity of the body? (cerebrum)5. List the four different lobes of the brain: (parietal lobe, occipital lobe, frontal lobe, temporal lobe)6. which structure transports deoxygenated blood back to the heart? (pulmonary artery)•