Blood PressureThis week, you will log in to eScienceLabs to complete the two lab exercise assignments. These labs cover the cCirculatory and rReproductive sSystems. You will learn about these systems via animations and pre-lab readings for the exercises. The animations will address the anatomy and physiology of blood and the heart, the circulatory system, blood pressure, and the reproductive system. The pre-lab readings will reinforce the elements of the circulatory system, including the role the respiratory system plays, the branches of the circulatory system, blood pressure, and cardiac output. You will viewView the Blood Pressure Virtual Lab animation before completing the Lab Report data and questions; data from the animation will be used in the Lab Report. Throughout the Blood Pressure lab, you will learn the basics on how to take a blood pressure reading, how blood pressure shows circulatory health, and what the normal sounds of blood pressure indicate, and how exercise impacts blood pressure. For this assignment you must:Complete the blood pressure and pulse reading table.Answers questions one through six
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WEEK 4 ASSIGNMENT 1: VIRTUAL LAB – BLOOD PRESSURE
Please complete your answers to the lab questions on this form. Please complete your answers,
and SAVE the file in a location which you will be able to find again. Then, attach and submit the
completed form to the Week 4 Laboratory dropbox in the Ashford University classroom.
Table 2: Blood Pressure and Pulse Readings
Blood Pressure (mmHg)
1. What is systolic pressure? What is diastolic pressure?
2. Why is blood pressure a sensible reading to measure circulatory health?
3. Explain the “lub-dub” sounds of the heartbeat.
4. Why do blood pressure and heart rate change after exercise?
5. How might the results in Table 2 change if someone else preformed the activities? Why?
© eScience Labs, 2013
6. Why is it important for blood to flow in only one direction?
© eScience Labs, 2013
The circulatory system is the major transportation system for the human body. It allows for transport of
nutrients, gases, electrolytes, hormones and cellular waste. Consider how important transportation of
these substances is for maintenance of the overall health of the human body. Disruptions to the proper
functioning of the circulatory system can result from various disease states and can have dire
The blood vessels of the circulatory system make up a closed system for transport of blood. As the heart
contracts, blood is propelled from the left ventricle into the aorta. From there, it travels through
successively smaller arteries before reaching arterioles, capillary beds, and finally tissues. Together with
the heart, the circulatory system is responsible for distributing blood to all the cells of the body.
Figure 1: The circulatory system showing the arteries in red and the veins in blue.
There are two systems identified in the circulatory system: the pulmonary system and the systemic
system.The pulmonary system is responsible for transporting blood to the lungs, where it becomes
oxygenated.The systemic system is responsible for delivering oxygenated and nutrient rich blood to the
rest of the body. Both are one-way systems, ensuring only oxygenated blood is pumped through the
Figure 2: The pulmonary and systemic circuits of the circulatory system.
Arteries are the largest vessels that transport oxygen-rich blood away from the heart to the tissues of
the body. However, there are two exceptions to this rule: pulmonary arteries, which transport oxygenpoor blood from the heart to the lungs; and, umbilical arteries which transport deoxygenated blood
from the fetus to the placenta. Arteries always consist of three layers, or tunica.
1. Tunica Intima: The inner layer facing the blood. It is composed of an innermost layer of simple
squamous epithelium surrounded by connective tissues.
2. Tunica Media: The middle layer. It is composed of smooth muscle with variable amounts of
3. Tunica Adventitia: The outer layer. It is composed of connective tissue.
There are three types of arteries in the body. The largest arteries of the body, such as the aorta, are
called elastic arteries. Most of these vessels are nearby to the heart, and have to expand as they receive
blood from the heart. These arteries have a large amount of elastic proteins in their tunica media,
allowing them the flexibility to expand when a bolus of fluid is ejected from the heart. When the heart
relaxes, the elastic properties of these arteries propel blood forward and the elastic arteries return to
their original size.Muscular arteries branch from elastic arteries and distribute the blood across the
body. Their name rises from an increased percentage of smooth muscle in the tunica media, enabling
the vessels to help regulate blood flow. To slow blood movement, these vessels can constrict by
contraction of the smooth muscle, and to increase blood flow muscles relax and they dilate. The final
subdivision from these arteries is a smaller vessel called the arteriole. These sometimes microscopic
vessels can also regulate blood flow through vasoconstriction and vasodilatation.
The next branch in the circulatory system is the capillary. These vessels have extremely thin walls,
consisting only of the tunica intima, some only one cell layer thick. Capillaries penetrate most of the
body’s tissue, creating a highly branched network of capillary beds. The thinness of their walls allows
oxygen and nutrients to diffuse from the vessel into surrounding tissues, and carbon dioxide and other
waste products to leave the tissues and enter the capillary. Many of these vessels are large enough for
blood cells to pass through in single line fashion, maximizing the potential for exchange. The types of
capillaries are outlined in Table 1.
After blood travels through the capillaries, it reaches a vein. Veins are the vessels that carry the oxygenpoor blood to the heart, where it can be pumped back to the pulmonary system to be reoxygenated. One exception to this is the pulmonary vein, which carries oxygen-rich blood from the lungs
to the left atrium of the heart. Post-capillary venules are the smallest vein. Similar to capillaries, veins
are porous, but have smooth muscle scattered throughout the tunica media. Different veins come
together to form venules. These vessels possess the three layers found in arteries (the tunica intima,
tunica media, and tunica adventitia), but are still somewhat more porous to allow the transfer of white
blood cells out of the vessel.Although veins possess all three layers typical to a blood vessel, the tunica
intima and tunica media are much thinner in comparison to those found in the arteries. However, the
tunica adventitia is well-developed. In some veins, such as those found in the limbs, the tunica
adventitia creates flaps inside the lumen of the vessel that form valves. Skeletal muscle surrounding
veins helps to pump the blood from chamber to chamber, with valves preventing backflow. This helps to
regulate the movement of the deoxygenated blood as it makes its way back to the heart.
Pressure is the driving force that keeps the blood flowing throughout all of the branches of blood
vessels. Hydrostatic pressure on the walls of the blood vessels is generated when the heart pumps blood
through an artery. Systolic pressure of arteries, measured when the ventricles are contracted, is equal
to about 120 mm Hg in healthy adults. Diastolic pressure is measured when the ventricles are relaxed
and is normally around 80 mm Hg (millimeters mercury) in arteries. As blood travels throughout the
arteries, resistance (and therefore pressure and velocity of blood flow) is reduced due to the change in
Recall the increase in smooth muscle cells, and resulting regulation of blood flow in arterioles. As the
blood enters the arterioles (the main resistance vessels of the system), pressure is sharply reduced and
continues to decline in the capillaries. Blood pressure in veins is nearly zero.These measurements are
useful diagnostic tools to understand cardiovascular health, and are monitored closely by several
systems in the body.
Figure 3: Blood volume influences blood pressure.
Concept Overview: Blood and the Heart
Cardiac output, the amount of blood ejected from the left ventricle, and resistance in blood vessels are
two measures that the body can alter when blood pressure is too high or too low. The cardiovascular
control center is located in the medulla oblongata, and is involved in regulating blood volume and blood
Virtual Learning: The Anatomy of the Heart
Higher brain centers and specialized sensors in blood vessels (baroreceptors for pressure and
chemoreceptors for chemicals) monitor the state of the circulatory system. Cardiac output can be
increased by increasing the heart rate as well as the force of contraction. Sympathetic cardiac
innervation allows this control by the cardiovascular center in the brain. Parasympathetic vagus
innervation of the heart allows the nervous system to decrease the heart rate. The vasomotor center is
connected to sympathetic nerves that innervate smooth muscle in arterioles. When the resistance in
these vessels needs to be changed, nerves stimulate the smooth muscle of arterioles accordingly.
Concept Overview: The Reproductive System
The Reproductive System
Most systems in the body are required for survival. However, the reproductive system is unique as it is
not mandatory for individual survival. In simplest terms, the reproductive system functions to propagate
a species. Reproduction involves the production of sperm and eggs, the processes leading to
fertilization, and embryonic development. The primary sex organs are called gonads – testes in males
and ovaries in females. These organs secrete hormones and produce gametes. Male gametes are
termed spermatozoa (sperm), and female gametes are termed ova (eggs).Accessory reproductive
organs include ducts, glands, and external genitals. The reproductive role of the male is to produce
sperm and deliver it to the female reproductive tract. The female produces eggs, which, when fertilized
with the sperm, creates the first cell of a new individual. After fertilization occurs, the female uterus
provides a nurturing, safe environment for an embryo to develop into a fetus until birth.
Male Reproductive Organs
The penis is a cylindrical organ that provides an exit route for urine and sperm. Internally, the penis
consists of three cylindrical masses of tissue, each of which is surrounded by a thin (but tough) layer of
fibrous connective tissue called the tunica albuginea. During erection, parasympathetic neurons
stimulate dilation of the arteries within the penis, causing the penis to enlarge and
stiffen. Similarly, ejaculation occurs when sympathetic neurons stimulate the discharge of semen.
Two testis reside within the scrotum, a sac that hangs from the base of the penis. A vertical septum
divides the scrotum into left and right compartments, each of which encloses one testis. Optimal sperm
production occurs at a temperature of approximately 35 – 36 °C (which is 1 – 2 °C below the core body
temperature). This is one reason why the scrotum hangs outside the body.
The testes have both an endocrine function (testosterone production) and an exocrine function (sperm
production). The spermatic cord connects each testis to the body cavity. The coiled seminiferous
tubules inside each lobule unite to form a straight tube, called the tubulus rectus.Endocrine cells,
called Leydig cells, cluster along the seminiferous tubules, and secrete testosterone. Testosterone
influences spermatogenesis and some of the secondary male sex characteristics. For example, within the
genital tract, testosterone promotes the development and control of the duct system and associated
Each testes transports sperm through a system of long, twisted tubes that comprise the bulk of the
organ. A two-layer outer membrane system called the tunica vaginalis surrounds each testis. The tunica
albuginea, which lies inside the tunica vaginalis, protrudes inward, divides each testis into lobules
containing seminiferous tubules where sperm production occurs. The epididymis is a comma-shaped
organ that lies adjacent to each testis. Each epididymis contains a tightly coiled tube called the ductus
epididymis. Sperm are held in this organ to complete their maturation here until ejaculation.
The remaining structures of the male reproductive system consist of the conduits and sources of
secretions that aid in the delivery of sperm to the body exterior or the female reproductive
tract. Smooth muscle cells surrounding the epididymis contract during ejaculation. This forces mature
sperm into the next tube called the ductus deferens (also called the vas deferens). The vas deferens is
the tube through which sperm travel when they leave the epididymis. Each tube loops around the
bladder and joins the ejaculatory duct. The ejaculatory ducts are short tubes that connect each vas
deferens to the urethra. The urethra is the passageway for urine and semen. The urethra ends at the
external urethral orifice.
Figure 5: Male reproductive organs.
Female Reproductive Organs
The ovary is the organ that produces eggs in the female reproductive system. Two ovaries are present in
each female and each is held in place by the mesovarium, the suspensory ligament, the broad ligament,
and the ovarian ligament. Each ovary is approximately the size of an almond. The ovary is covered by a
layer of epithelium and the tunica albuginea. The inside of the ovary is divided into two indistinct
regions, the outer cortex and the inner medulla. Ovarian follicles are embedded in the cortex. Each
follicle contains a primary oocyte surrounded by one or more layer of follicular cells that nourish the
oocyte as it matures. The Fallopian tubes (also called the oviducts or uterine tubes) transport the
secondary oocytes away from the ovary and toward the uterus during menstruation.
The uterus is a hollow organ in which fetal development occurs. It is characterized by four regions. The
upper region is called the fundus. The central region is called the body, the lower, narrow region is
called the isthmus, the cervix is a narrow region at the bottom of the uterus that leads to the
vagina. The uterus is held in place by the broad ligaments, uterosacral ligaments, round ligaments, and
cardinal ligaments. The wall of the uterus consists of the perimetrium, a serous membrane that lines the
outside of the uterus, and the myometrium containing several layers of smooth
muscle. The endometrium is the highly vascularized mucosa that lines the inside of the uterus.
Figure 6: Female reproductive organs.
The vagina serves both as the passageway for a newborn, and the site for sperm deposition. The upper
vagina surrounds the cervix, and the lower vagina opens to the outside at the vaginal
orifice. The vulvae make up the external genitalia – the mons pubis, labia major, labia minora, the
versibule, and the clitoris.
The mammary glands are a type of sweat glands that specialize in milk production. The milk-producing
secretory cells form walls of bulb-shaped chambers called alveoli that join together with ducts to form
clusters called lobules. Groups of lobules assemble to form a lobe. Each breast contains a single
mammary gland consisting of 15 – 20 lobes. Lactiferous ducts lead away from the lobes and widen into
lactiferous sinuses that serve as temporary reservoirs for milk. The ducts narrow again as they lead
through a protruding nipple. The nipple is surrounded by a ring of pigmented skin called the
areola. During pregnancy, estrogen and progesterone stimulate extensive development of the
mammary glands and its associated ducts. After childbirth, various hormones, namely prolactin, initiate
lactation. When neurons are stimulated by the sucking of an infant, nerve impulses activate the
posterior pituitary to secrete oxytocin, stimulating contraction of the cells surrounding the alveoli. Milk
is then forced toward the nipple in what is called the letdown reflex.
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