BRAIN STRUCTURE AND PHYSIOLOGY

THE NERVOUS SYSTEM

TWO MAJOR DIVISIONS

• The Central Nervous System (CNS)• Peripheral Nervous System (PNS)

THE CENTRAL NERVOUS SYSTEM

Controls 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 transmit information

1. Cell Body - contains the nucleus and two extensions

2. Dendrites – shorter, more numerous, receive information

3. Axons – single, long “fiber” which conducts impulse away from the cell body, sends information

BASIC DIVISIONS OF THE NERVOUS SYSTEM

CARDIOVASCULAR SYSTEM

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 Valves (AV) & 2 Semilunar valves)

• Left Atrioventricular valve – 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

• Pulmonary Semilunar, or just pulmonary valve. Between the left ventricle and the aorta

BLOOD VESSELS

•Blood Vessels:  arteries, veins, capillaries

•ARTERIES :  strong elastic vessels which carry blood moving away from the heart.   Smallest ones are arterioles which connect to capillaries.•VEINS - Thinner, less muscular vessels carrying blood toward the heart.  •Smallest ones are called venules which connect to capillaries.  Contain valves.

CAPILLARIES

Penetrate nearly all tissues.  Walls are composed of a single layer of squamous cells – very thin.  Critical function: allows exchange of materials (oxygen, nutrients) between blood 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)

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• Superior and Inferior Vena Cava – return blood from the head and body to the heart (connects to right atrium)

MALE REPRODUCTIVE SYSTEM

Major 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 remain outside the body cavity. Temperature 37°C.

• Seminiferous tubules: located in the testis are clusters of hundreds of tiny tubules.

• Epididymis: where fully matured sperm are stored.

• Testes: makes sperms, produces testosterone.

• Vas deferens: the tube that carries sperm from the epididymis to the urethra.• Urethra: tube that

carries urine from the bladder and releases it from the body.• Penis: contain a

tube(urethra) that leads to the outside of the body.

FEMALE REPRODUCTION

Main Structures•Ovary•Uterus•Fallopian Tubes•Vagina•Cervix

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

FEMALE REPRODUCTIVE SYSTEM

• Cervix• Fallopian Tubes• Vagina• Ovary• Uterus

REVIEW QUESTIONS

Questions:1.Name the stage of development the embryo is a hollow ball of

identical cells:2. 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 ANSWERS

Questions: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)

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