The physiological functions of hypothalamus related to both endocrine and autonomic nervous system. and the 12 cranial nerves with their nature (sensory, motor, or mixte) , their functions and their origin

1. State the physiological functions of hypothalamus related to both endocrine and autonomic nervous system.
2. list the 12 cranial nerves stating teir nature (sensory, motor, or mixte) stating their functions and their origin

1. CLARKE INTERNATIONAL UNIVERSITY

ALLIED HEALTH SCIENCES
CLINICAL MEDICINE AND COMMUNITY
HEALTH


NAME : NDAYISABA CORNEILLE
REG NO : 2017-DCM –FT- 003
YEAR : ONE SEMESTER TWO
COURSE UNIT : PHYSIOLOGY II

LECTURER : MR SSERUGO ISAAC

QUESTIONS:
1. State the physiological functions of hypothalamus
related to both endocrine and autonomic nervous
system.
2. list the 12 cranial nerves stating teir nature
(sensory, motor, or mixte) stating their functions
and their origin

2. 1.Hypothalamus is a portion of the brain that contains a number of small nuclei with a
variety of functions. One of the most important functions of the hypothalamus is to link
the nervous system to the endocrine system via the pituitary gland (hypophysis).
It is located below the thalamus and is part of the limbic system.
Its function is for:

I-the regulation of certain metabolic processes and other activities of the autonomic
nervous system.
1.The cells that drive the ANS are located in the lateral medulla. The hypothalamus projects
to this area, which includes the parasympathetic vagal nuclei, and also to a group of cells
which lead to the sympathetic system in the spinal cord. By interacting with these systems, the
hypothalamus controls digestion, heart rate, sweating and other functions.
2.The main function of the hypothalamus is homeostasis which is the ability to keep a system
at a constant condition. Factors such as blood pressure, fluid and electrolyte balance, and body
weight are held to a precise value called the set-point
3.Limbic system- the limbic system is composed of the hypothalamus, the amydala, the
hippocampus, and other nearby areas. These structures lie on both sides of the thalamus, just
under the cerebrum.
4.Hypothalamus as the center for the limbic system which connected with the frontal lobes,
septal nuclei and the brain stem reticular formation via the medial forebrain bundle, with the
hippocampus via the fornix, and with the thalamus via the mammillothalamic fasciculus. It
regulates a great number of autonomic processes.
5.Mammillary bodies, part of the hypothalamus that receives signals from the hippocampus
via the fornix and projects them to the thalamus.
6.It is responsible for the regulation of certain metabolic processes and other activities of
the autonomic nervous system where It synthesizes and secretes certain neurohormones,
called releasing hormones to the pituitary gland
7.It is the processing centre in the brain that controls body temperature. It does this by
triggering changes to effectors, such as sweat glands and muscles controlling body hair. Heat
stroke can happen when the bodybecomes too hot; and hypothermia when the body becomes
too cold.
8.It is the important part of the brain that controls things like thirst, hunger and the release of
many hormones.

3. 9.Hypothalamus play a big function in the following activities of autonomic nervous system
in order to sustain :
On the Heart there is control of heart rate via contractility, refractory states, cardiac
conduction
On the Blood vessels there is constriction and dilation of arteries/veins
On the Lungs, it involve in relaxation of smooth muscles of the bronchioles.
On the Digestive system, there is gastrointestinal motility, saliva production, sphincter
control, insulin production in the pancreas, etcetera

Reproductive system the males, erection and ejaculation; in females, contraction and
relaxation of the uterus
On the Urinary system ,involves the relaxation and contraction of bladder and detrusor
muscles, urethral sphincte
10.Inputs also reach the hypothalamus from the retina and in the form of direct physical
stimuli. Axons of some retinal ganglion cells terminate in the small suprachiasmatic
nucleus on each side of the
anterior hypothalamus.
.
Hypothalamic outputsto the limbic system and other forebrain structures include:
1. The mammillothalamic tract (from the mammillary bodies to the anterior nuclear group)
from which projections are sent to the cingulate gyrus.
2. The fornix (to the hippocampal formation)
3. The striaterminalis(to the amygdala, septal rim,)
II- Hypothalamus synthesizes and secretes certain neurohormones, called releasing
hormones (from anterior pituitary) or Neurohypophysial hormones (from posterior
pituitary ), and these in turn stimulate or inhibit the secretion of pituitary hormones.
Which are listed below and their function related to endocrine system:

4. II.1.Releasing hormones : also known as hypophysiotropic or hypothalamic hormones are
synthesized by neurons in the hypothalamus. And then are stored and released into
the hypophyseal portal system. then rapidly reach at anterior pituitary where they exert their
hormonal action
Hypophysiotropic hormones include:
II 1.1 Thyrotropin-releasing hormone (TRH). TRH production stimulates the pituitary
gland to produce thyroid-stimulating hormone (TSH). TSH plays an important role in the
function of many body parts, such as the heart, gastrointestinal tract, and muscles.
II.1.2.Corticotropin-releasing hormone (CRH). CRH is involved in the body’s response to
both physical and emotional stress. It signals the pituitary gland to produce a hormone called
II.1.3 adrenocorticotropic hormone (ACTH). ACTH triggers the production of cortisol, an
important stress hormone.
II.1.4 Gonadotropin-releasing hormone (GnRH). GnRH production causes the pituitary
gland to produce important reproductive hormones, such as follicle-stimulating hormone
(FSH) and luteinizing hormone (LH).
In females, LH works with FSH to cause maturation of an egg-containing ovarian follicle.
LH then independently triggers ovulation and promotes synthesis and release of ovarian
hormones.
In males, LH stimulates the interstitial cells of the testes to produce the male hormone
testosterone.

II.1.5 prolactin. This hormone controls many important behaviors and emotions, such as
sexual arousal, trust, recognition, and maternal behavior. It’s also involved in some functions
of the reproductive system, such as childbirth and lactation.
II.1.6 Somatostatin. Somatostatin works to stop the pituitary gland from releasing certain
hormones, including Promotes growth (indirectly), control of protein, lipid and carbohydrate
metabolism
The anterior region of the hypothalamus also helps regulate body temperature through sweat.
It also maintains circadian rhythms. These are physical and behavioral changes that occur on a
daily cycle. For example, being awake during the day and sleeping at nighttime is a circadian
rhythm related to the presence or absence of light.

II.2 Neurohypophysial hormones

5. Neurohypophysial hormones are synthesized in the magnocellular secretory neurons of the
hypothalamus. are stored and released into the systemic circulation. The synthesis, control,
and release of those hormones is co-regulated by hormonal, local and synaptic signals
Neurohypophysial hormones include:
II.2.1 Oxytocin : its function is on Uterus is to stimulates uterine contractions; initiates
labor;and it also acts as the hormonal trigger for milk ejection in women whose breasts are
producing milk in response to prolactin

II.2.2 Antidiuretic hormone (ADH) or vasopressin : it regulates water levels in the body.
When vasopressin is released, it signals the kidneys to absorb water, thus allows water
reabsorption and excretion of concentrated urine

2.The cranial nerves are nerves that arise from the brain and exit the skull through holes
(cranial foramina) at its base rather than through the spinal cord.
Cranial nerves are responsible for the control of a number of functions in the body. Some of
these functions include directing sense and motor impulses, equilibrium control, eye
movement and vision, hearing, respiration, swallowing, smelling, facial sensation, and tasting.
The names and major functions of these nerves are listed below.
The names and major functions of these nerves are listed below.
1.Olfactory Nerve its nature is sensory which orginate in Telencephalon. And its function
to carry afferent impulses for sense of smell

2.Optic Nerve its nature is sensory which orginate in Retinal ganglion cells. And its
function is to Transmits visual signals from the retina of the eye to the brain.( in order word it
carries afferent impulses for vision)

3.Oculomotor Nerve its nature is a motor which orginate in Anterior aspect of Midbrain.
And its function is to Innervates the levator palpebrae superioris, superior rectus, medial
rectus, inferior rectus, and inferior oblique, which collectively perform most eye movements.
Also innervates the sphincter pupillae and the muscles of the ciliary body.

4.Trochlear Nerve its nature is motor which orginate from Dorsal aspect of Midbrain. And
its function to supply somatic motor fibers to (and carry proprioceptor fibers from) one of the
extrinsic eye muscles, the superior oblique muscle .

6. 5.Trigeminal Nerve: is the largest cranial nerve ,fibers extend from pons to face, and form
three divisions: ophthalmic, maxillary, and mandibular divisions. As major general sensory
nerves of face, transmit afferent impulses from touch, temperature, and pain receptors. Cell
bodies of sensory neurons of all three divisions are located in large trigeminal ganglion. its
nature is mixte . And its function : At ophthalmic division it Conveys sensory impulses
from skin of anterior scalp, upper eyelid, and nose, and from nasal cavity mucosa, cornea, and
lacrimal gland. At maxillary division it Conveys sensory impulses from nasal cavity mucosa,
palate, upper teeth, skin of cheek, upper lip, lower eyelid. And mandibular divisions it
Conveys sensory impulses from anterior tongue (except taste buds), lower teeth, skin of chin,
temporal region of scalp; suppliesnmotor fibers to, and carries proprioceptor fibers from,
muscles of mastication

6.Abducent Nerve: its nature is motor which orginate from Nuclei lying under the floor of
the fourth ventricle (Pons). And its function is to supply somatic motor fibers to lateral rectus
muscle, an extrinsic muscle of the eye; convey proprioceptor impulses from same muscle to
brain.

7.Facial Nerve: its nature is mixte which orginate from Pons. Is the chief motor nerves
of face with five major branches: temporal, zygomatic, buccal, mandibular, and cervical. And
its function is to provides motor innervation to the muscles of facial expression, posterior
belly of the digastric muscle, stylohyoid muscle, and stapedius muscle. Also receives the
special sense of taste from the anterior 2/3 of the tongue and
provides secretomotorinnervation to the salivary glands (except parotid) and the lacrimal
gland.

8. Vestibulocochlear nerve: its nature is sensory which orginate from the inner ears and
goes to the pons. And its function is to mediates sensation of sound, rotation, and gravity
(essential for balance and movement). More specifically, the vestibular branch carries
impulses for equilibrium and the cochlear branch carries impulses for hearing.

9.Glossopharyngeal Nerve: its nature is mixte which orginate from Medulla.And its
function is Swallowing, sense of taste, and saliva secretion

7. 10.Vagus Nerve: its nature is mixte which orginate from posterolateral sulcus
of Medulla.And its function is the control of parasysmpathetic Nervous system (PNS) e.g.
smooth muscles of Gastrointestinal tract , lungs and heart.
11.Accessory Nerve: its nature is motor which orginate from Cranial and Spinal Roots.And
its function is to Controls the sternocleidomastoid and trapezius muscles, and overlaps with
functions of the vagus nerve

12.Hypoglossal Nerve: its nature is motor which orginate from Medulla.And its function
is to provides motor innervation to the muscles of the tongue (except for the palatoglossal
muscle, which is innervated by the vagus nerve) and other glossal muscles. Important
for swallowing (bolus formation) and speech articulation.





Reference:
. Elain N . M,Kata H.human anatomy and physiology pearson Benjamin cumming 2007
. Essentials of Anatomy and Physiology-Valerie C. Scanlon-2007
. Bear, Mark F. "Hypothalamic Control of the Anterior Pituitary." Neuroscience: Exploring
the Brain. 4th ed. Philadelphia: Wolters Kluwer, 2016. 528. Print.
. Principles of anatomy and physiology (12th ed) - Tortora