Lab 11 Fetal Pig II Excretory, Reproductive (Urogenital) & Nervous Systems PDF

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Lab 11 Fetal Pig II: Excretory, Reproductive (Urogenital) & Nervous Systems 1.) General Information Time is short. Lab 11 is your last chance to have a full lab period with the pig before the lab practical exam. After you finish the new dissections and observations, review the previous structures and organ systems from last week for the pig, fish and frog. There are slides to observe and some to draw as well. There is a pre-lab quiz and a flat screen quiz for this lab. The last lab (#12) covers development and you will have only limited time to review any preserved specimens and slides. Next week is the Development lab and then the final practical exam and written quiz covering the second half only, all animals. The second set of drawings is due at the practical. All specimens and slides from the second half are fair game for the practical. There are a variety of questions posted on Blackboard as well as the lab manual to review for the final quiz. You can help yourself out with a good score on these two lab exams. 2.) Objectives for this lab: 1. Examine the structure and function of the excretory (urinary) system in the fetal pig from the formation of urine in the Kidney to the exit of the fluid from the body. 2. Examine the structures and function of male and female reproductive systems in the fetal pig, paying attention to difference in function, structures and location. 3. Examine the structures and function of select components of the nervous system a. Examine basic structure and function of a neuron (nervous tissue) b. Examine basic structure and function of a simple reflex arc; path of sensory input, integration and motor output or response c. Examine example sensory structure – the sheep eye d. Examine structure and function of a vertebrate (sheep) brain. 4. Examine the comparative brain anatomy of three representative vertebrates. 3.) Lab Format: a.) Exercise 1: p. 344 Symbiosis, Excretory (kidney) System; structure & function Examine the kidney and its connection to the bladder, the ureter (know fetal modifications). A Detailed examination of the kidney internal structure uses a sheep kidney. Follow the dissection protocol from the handout (with the sheep heart). You will need to know about the structure involved in the production of urine on both the macro and micro scale (slide), the whole organ to Bowman’s capsule and glomerulus, see Atlas b.) Exercise 2, p. 347, Male & Female Reproductive Systems Part 1 – male: The testis are enclosed in the scrotal sac, but not descended. To find the male testis and the ductus (vas) deferens connection, you have to open the abdominal wall of the pig (fig. 2a, & 2b p. 348/49 and the Atlas. Attached to the testis you will see the spiral Epididymis. The opening through body wall is the inguinal canal. The glands associated with semen fluid production are not well developed, but usually the Seminal Vesicles and the Bulbourethal glands are visible. To see these glands and follow the path of the urethra from the bladder to the penis, carefully split the pelvic girdle and follow the urethra to its ventral exit. Part 2 – female: The female reproductive system is enclosed in the abdominal cavity. Posterior to the kidneys on each side of the abdominal cavity you will see the two ovaries. The oviducts or uterine tubes are difficult to see, but may look like small fingers wrapped around the ovary. The fan like uterine horns connect to the body of the uterus. The vagina and the urethra fuse in the fetal pig in the vaginal vestibule (also called urogenital sinus). Split the pelvic girdle to follow the urethra to where it exits at the urogenital opening, fig. 3a & 3b, p. 352/53. c.) Exercise 3: Lab Study A; a typical neuron, diagram is fig. 5 p. 356 in Symbiosis. See the slide in lab. Atlas has several examples. A neuron is the unit of function and structure of the nervous system. 1

- cell body- contains nucleus and other organelles necessary for the life of the cell. - dendrites-the input end of the neuron. Signals come into the cell body from the dendrites - axon- the output end of the cell. Signals travel the length of the axon. The signal then goes on to another neuron through its dendrite or to an effector. (gland, muscle, etc.) - axons can be covered with myelin sheath which serves to speed up the impulse as it travels down axon. - the synapse between neurons is the chemical part of nervous communication. The synapse is where most external control of the nervous systems takes place in terms of chemical interactions, legal or illegal. Lab Study B; Simple Relex Arc and Cross Section of the Spinal Cord; Simple Reflex Arc; use figure 6 p. 357 and supplement it with Campbell and the Atlas. You can model this physiological response by tapping the patellar tendon at the distal base of the kneecap gently with a rubber mallet (if available) or the side of your hand. If you do the experiment while you clasp your hands together in front of your chest and pull, the knee response often increases. Why might this be? Spinal cord; look at the diagram in Symbiosis (fig. 6). There is also a slide of a cross section of a spinal cord and in the Atlas. Where do you see cell bodies of neurons (part a) in this cross section? - dorsal root, ventral root, gray matter, white matter central canal - sensory neuron input via dorsal root from a receptor. - cell bodies of sensory neurons lie in the dorsal root ganglion. -interneuron in gray matter-intermediary between sensory and motor neuron as well as to neurons leading to the brain allows for control and integration of response. -motor neuron - send output signal via the ventral root to an effector, such as a muscle. -motor neuron cell bodies lie in gray matter. Look at the slide of a cross section of the spinal cord to see gray matter, white matter, central canal, dorsal root, ventral root Lab Study C; Eye Dissection, p. 359. The major caution for the eye dissection is to not grab the eye tightly and compress the eye when making the initial puncture of cut of the body of the eye with scalpel or scissors. A gusher of the vitreous humor and preservative will spray out if you do. The incision to open the eye should be a transverse cut (fig. 7 p. 359) to separate a frontal section (similar to the heart dissection) that includes the cornea and the lens with the iris and leave the anterior structures like the lens and cornea intact. At the posterior of the eye, pay particular attention to the retina and the optic nerve. What and where is the blind spot? The stub of tissue exiting the rear of the eye (opposite to the cornea) is the optic nerve that connects to the optic chiasma of the brain. You saw this structure at the ventral base of the brain. You can practice finding your blind spot. You can’t see the functional structure of the retina, layers of neurons. Essentially the retina makes the eye a light sensing organ for the brain. Review how the eye works, how the image is focused on the retina. See Campbell. The Atlas is sparse in this area, but has some pictures. See handout on Blackboard for eye structures. d) Additional Exercise: Sheep Brain Dissection. Follow the supplemental sheep brain dissection handout from Blackboard. Bisect the brain at the midline anterior to posterior, through the frontal cortex, cerebellum and brain stem. The result will look like the longitudinal view in the pictures on Blackboard and atlas. Use the brain list to help ID structures. Depending on what the brains look like out of the bucket, you may have to remove dura and even skull parts. Again depending on brain condition, look for ventral structures like olfactory bulbs, optic chiasma and any cranial nerves (skip names). Brain diagrams may have more labels than are necessary, see the things to know list for required structures. Look for the optic nerves & chiasma before removing dura coverings. Compare the sheep brain to the human brain. There is a human brain model in the lab, or see Atlas. How does our vertical life change the orientation of our brain from the sheep or fetal pig? What else to you see in terms of human structure or size? Look at the models of the lower vertebrates (fish & frog) to understand the evolutionary development and dominance of the cerebral component. 4.) Additional systems (optional) a.) Endocrine System: Endocrine glands respond to stimuli by secreting hormones into the blood to be 2

transported to target tissues that then bring about the response. Endocrine glands observed: thymus, thyroid, pancreas testes, ovaries and adrenals. The endocrine system is an important part of the maintenance of internal body conditions by coordinating physiological processes, AKA homeostasis. Part b following outlines the hierarchy of the different pars of the nervous system. You do not need to remember all this material in detail. It helps to put the function of the nervous system in context of the body. b.) Command and control system for homeostasis (combined, central and peripheral systems). Nervous System can be subdivided into two major systems (see Campbell) a) Central Nervous System - comprised of brain and spinal cord b) Peripheral N.S. - Spinal nerves leading to and from spinal cord, Cranial nerves leading to and from brain. System is further subdivided into two components. 1. Somatic N.S. Our model is the basic reflex arc, Chapter 49 in Campbell (see below). - sensory neurons send information FROM receptors in head, body wall and extremities TO the central nervous system by afferent neurons. This is input of outside stimuli - motor neurons send information FROM the central nervous system TO the skeletal muscles by efferent neurons. Controls primarily voluntary actions, response to the outside stimuli 2. Autonomic N.S. (system will not be covered in detail) - sensory neurons send information FROM receptors in the viscera (internal organs) TO the CNS. - motor neurons send information FROM the CNS TO the smooth muscle, cardiac muscle and glands. The brain stem controls involuntary actions.(ex: breathing, heart rate, digestion, etc). Both sensory and motor neurons are part of parasympathetic (normal function) and sympathetic (functions during stress) systems, p.1083/84. The classic example is the flight or fight response. The endocrine system is also active. 5.) Lab 11: Things To Know for the Nervous & Reproductive Systems Know the structure of a neuron and the basic simple reflex arc & spinal chord. You will not be tested on the placement of the nerves in the body of the pig. We will not cover the endocrine system in detail and not the autonomic nervous system. Know the structures you have seen with a function. Nervous System Vertebrae / Vertebral canal Axon, cell body, dendrite Sensory / motor neuron Gray matter / White matter Dorsal (sensory) and ventral (motor) roots of spinal nerves Dorsal root ganglia

Endocrine System Thyroid Thymus Adrenal glands Gonads (ovaries or testis) Pancreas Pituitary Pineal

Sheep Brain Dura matter Cerebrum (frontal, temporal, parietal, occipital) Cerebral hemispheres Corpus callosum Olfactory bulbs Optic chiasma (optic nerves) Thalamus / Hypothalamus Cerebellum / Pons / Medulla oblongata Spinal chord

Eye Layers: Sclera / Cornea / Choroid / Retina Tunics (fibrous, vascular, retinal) Iris / Pupil / Ciliary body / Lens Optic nerve / Blind spot Tapetum (not in humans) Aqueous humor (between cornea and lens) Vitrious humor (between lens and retina)

Reproductive system – Male 1. Preputial orifice 2. Penis 3. Urethra

Female Ovary Uterine tubes Uterine horns 3

4. Bulbourethral glands (Cowpers) 5. Ductus deferens (Vas) 6. Seminal vesicles 7. Prostate gland 8. Spermatic cord 9. Scrotal sac 10. Testis 11. Epididymis 12. Gubernaculum 13. Inguinal canal

Uterine body Cervix Vagina Urethral opening into urogenital sinus Urogenital sinus Vulva Genital papilla

Excretion (Sheep kidney for internal structures) 1. Kidney (know basic function including unit of function; the nephron) 2. Retroperitoneal (location description 3. Adrenal glands (know location & function) 4. Renal artery / Renal vein 5. Ureter / urethra (male v. female structures, path & opening location done with reproduction) 6. Allantoic stalk (connections to placenta) 7. Bladder (allantoic) 8. Internal structures of the kidney as related to urine production and water/salt balance.

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