Unit 6,7,8 A N P

Question 1

Organization of the nervous system
= brain and spinal cord
= midline or central
=central nervous system or CNS

PNS = nerves of the body
= Nerves extend to outlying or peripheral
subdivision of PNS = called autonomic nervous system or ANS
= consist of structures the regulate the body’s autonomic or involuntary functions. ex= heart rate, stomach and intestine and chemical secretions

Question 2

cell of the NS

Answer 2

two major types of cells
neurons or nerve cells
glia = supporting cells

Question 3

neuron structure

Answer 3

three parts
main part is called cell body
one or more branching called dendrites
elongated projection called axon

Question 4

Dendrites are the processes or projections that. carry impulses to the neuron cell bodies
axon are the processes that carry impulses away from the neuron cell bodies

Question 5

types of neurons

Answer 5

sensory neurons = carry impulses to the spinal cord and brain from all parts of the body. also called afferent neurons
motor neurons = carry impulses in the opposite direction - away from the brain and spinal cord. Also called efferent neuron
Interneuron = conduct impulses from sensory neurons to motor neurons. they often connect to form complex, central networks of the nerve fivers. they are sometimes called central or connecting neuron

Question 6

Glia or neuroglia cells
they don’t do impulses, instead, they support the cells.
one function of glial cells is to hold the functioning neurons together and protect them

Question 7

central glia

Answer 7

vary in shape and size
threadlike extensions that jut out from their surfaces and are called astrocytes = their threadlike branches attach to neurons and small blood vessels. holding the structures close to each other.

Question 8

Blood vessel astrocytes or BBB

Answer 8

separates the blood tissue and nervous tissue to protect vital brain tissue from harmful chemicals

Question 9

microglia = are smaller than astrocytes. they usually remain stationary, but inflamed or degenerating brain tissue, they enlarge, move about, and act as microbes eating scavengers
OlIGODENDROCYTES = help to hold the nerve fibers together and also serve another and probably more important function: they produce fatty myelin sheath that envelops nerve fibers located in the brain and spinal cord

Question 10

Peripheral Glia

Answer 10

Schwann cells are glial cells that also form myelin sheaths but do so only in the PNS

Astrocytes have extensions attached to blood vessels in the brain.
Microglia within the central nervous system can enlarge and consume microbes by phagocytosis
Oligodendrocytes have extensions that form myelin sheaths around axons in the central nervous system.
Peripheral glia: D, Schwann cells wrap around axons in the peripheral nervous system to form myelin sheath.

Question 11

neurons with myelin-wrapped axons are called myelinated fibres
nodes of Ranvier = which are gaps between adjacent Schwann cells.
the outer wrapped layer of a Schwann cell is called the neurilemma

Question 12

CNS DOES NOT HAVE SCHWANN CELLS, no neurilemma

Largest part of the brain is the cerebrum. Which divided into two sides called hemispheres
Frontal lobe is for personality and emotions higher thinking skills and controlling movements
Temporal lobe process hearing and other senses helps with language and reading
Parietal lobe is involved with our senses ,attention, and language
Occipital lobe helps your eyes see including recognition of shapes and colours
Thalamus relay sensory and motor information of the cortex, helps with consciousness,sleep, and alertness
12 pairs of cranial nerves carry information from senses to from the brain
Cerebellum motor control coordination and spatial navigation
Brainstem nerve pathway that runs away all down the back sending and receiving
Pons controls are breathing
Medulla oblongata heart and body reflexes like swallowing,vomiting and coughing
Lambic system region under the cortex processes our emotions and drive
Reward circuits called dopamine making us feel pressure
Amygdala process the emotions
Hippocampus memory indexer
Hypothalamus gets the adrenaline flowing
Pituitary gland master gland helps controls growth body temperature and health
Pineal gland helps control sleeps and circadian rhythms
Ascending tracts conducts impulses up to the spinal cord to the brain
Descending tracts conduct impulse’s down the spinal cord to the brain

Question 13

nerves and tracts
nerve is a group of peripheral nerve fibres (axon) bundled together like the strands of cable.
Peripheral nerve fibres usually have myelin sheath

a thin wrapping of fibrous connective tissue called the endoneurium.

Groups of these wrapped axons are called fascicles.

A tough, fibrous sheath called the epineurium covers the whole nerve.

Bundles of axons in the CNS, called tracts, also are my- elinated and thus form the white matter of the brain and spinal cord.

Brain and spinal cord tissue composed of cell bodies and unmyelinated axons and dendrites is called gray matter because of its characteristic gray appearance.

Question 14

Nerve impulses, also called action potentials, can travel over trillions of routes—routes made up of neurons because they are the cells that conduct impulses.
Neuron Pathways

A basic type of neuron pathway called a reflex arc, is important to nervous system functioning.

Receptors are the beginnings of dendrites of sensory neurons. They are often located far from the spinal cord

A ganglion is a group of nerve-cell bodies located in the PNS. located near the spinal cord

Question 15

A microscopic space separates the axon ending of one neuron from the dendrites of another neuron. This gap serves as a junction between nerve cells called a synapse.
The nerve pulse stops at the synapse, chemical signals are sent across the gap, and then a new impulse continues along the dendrites, cell body, and axon of the motor neuron

The motor neuron axon forms a synapse with a structure called an effector, an organ that puts nerve signals “into effect.

Effectors are usually muscles or glands, and muscle contractions and gland secretion are the kinds of reflexes operated by
these effectors

An involuntary response to impulse conduction over a reflex arc is called a reflex.

In short, impulse conduction by a reflex arc causes a reflex to occur. In our example reflex, the nerve impulses that reach the quadriceps muscle (the effector) result in the “knee-jerk” response.

application of an irritating stimulus to the skin of the thigh initiates a three-neuron reflex response that causes contraction of muscles to pull the leg away from the irritant—a three-neuron arc reaction called the “withdrawal reflex”

Question 16

An excess of sodium ions (Na+) on the outside of the membrane polarizes the axon.

Stimulation of the
membrane triggers Na+ inward diffusion of
Na+, depolarizing
the membrane.

Membrane repolarizes as original state is achieved.

Question 17

saltatory conduction, this type of impulse travel, is much faster than is possible in nonmyelinated sections

a synapse is the place where impulses are transmitted from one neuron, called the presynaptic neuron, to another neuron, called the postsynaptic neuron.

A synaptic knob is a tiny bulge at the end of a terminal branch of a presynaptic neuron’s axon. Small sacs or vesicles

Each vesicle contains a very small quantity of a chemical compound called a neurotransmitter.

When a nerve impulse arrives at the syn- aptic knob, neurotransmitter molecules are released from the vesicles into the synaptic cleft.

The synaptic cleft is the space between a synaptic knob and the plasma membrane of a postsynaptic neuron.

Neurotransmitters are chemicals by which neurons communicate

acetylcholine (ACh) is released at some of the synapses in the spinal cord and at neuromuscular (nerve-muscle) junctions. Other well-known neurotransmitters include norepinephrine, dopamine, and serotonin. They belong to a group of compounds called amines, which may play a role in sleep, motor function, mood, and pleasure recognition.

Two morphinelike neurotransmitters called endorphins and enkephalins are released at various spinal cord and brain synapses in the pain conduction pathway. These neurotrans- mitters inhibit conduction of pain impulses. They are natural pain killers.

Very small molecules such as nitric oxide (NO) also have an important role as neurotransmitters

Action potential conducted along the axon reaches the axon knob

Action potential triggers release of neurotransmitters from vesicles

3 Neurotransmitters cross synaptic cleft and bind to postsynaptic receptors
4 Activated receptors trigger opening of ion channels, initiating a postsynaptic impulse

Question 18

Acetylcholine (ACh) = excitatory or inhibitory; regulates parasympathetic effec- tors; involved in memory
Norepinephrine (NE) = Excitatory or inhibitory; regulates sympathetic effectors; involved in emotional responses
Dopamine = Mostly inhibitory; regulates motor control; involved in emotions and moods
Serotonin = Mostly inhibitory; involved in sleep, emotions, and moods
Endorphins and enkephalins = Mostly inhibitory; involved in blocking pain
Nitric oxide (NO) = Signal from presynaptic to postsynaptic neuron

Question 19

CNS issa importart part

Question 20

The brain is protected in the cranial cavity of the skull, and the spinal cord is surrounded in the spinal cavity by the vertebral column. In addition, the brain and spinal cord are also protected by three membranes called meninges, which are discussed in a later section of this chapter.

Question 21

Division of the brain

Answer 21

I. Brainstem
A. Medulla oblongata B. Pons
C. Midbrain
II. Cerebellum
III. Diencephalon
A. Hypothalamus B. Thalamus
C. Pineal gland
IV. Cerebrum

Question 22

Brainstem = consists of medulla oblongata, pons, and midbrain

The medulla oblongata is an enlarged, upward extension of the spinal cord. It lies just inside the cranial cavity, above the large hole in the occipital bone called the foramen magnum

The pons bulge out a bit more than the medulla, forming a bridge to the narrower midbrain.

In the brainstem, small bits of gray matter mix closely and intricately with white matter to form the reticular formation (reticular means “netlike”)

The cardiac, respiratory, and vasomotor centers (collectively called the vital centers),

Question 23

The cerebellum = is the second largest part of the human brain. It lies under the occipital lobe of the cerebrum.
Function = The most obvious functions of the cerebellum, then, are to produce smooth coordinated movements, maintain equilibrium, and sustain normal postures

Diencephalon = small but important part of the brain located between the midbrain below and the cerebrum above.
It consists of three major structures: hypothalamus, thalamus, and pineal gland. Find these structures in before reading further

Question 24

Just above the hypothalamus is a dumbbell-shaped section of gray matter called the thalamus. Each enlarged end of the dumbbell lies in a lateral wall of a fluid-filled chamber called the third ventricle.

The thalamus performs the following functions:
Relays sensory information. Its neurons relay impulses to the cerebral cortex from the sense organs of the body

Associates sensations with emotions. Almost all sensations are accompanied by a feeling of some degree of pleasantness or unpleasantness

Regulates level of consciousness. It plays a part in the so-called arousal or alerting mechanism that keeps us awake.

Participates in motor reflexes. It plays a role in mechanisms that produce complex reflex movements.

Question 25

Posterior to the thalamus is a tiny mass protruding from the back of the diencephalon called the pineal gland or pineal body.
resembles a pine nut or kernel corn

Melatonin is known as “the timekeeping hormone” because it helps to keep the body’s clock “on time” with the daily, monthly, and seasonal cycles of sunlight and moonlight.

Question 26

cerebrum = is the largest and uppermost part of the brain. If you were to look at the outer surface of the cerebrum, the first features you might notice are its many ridges and grooves.

The ridges are called convolutions or gyri, and the grooves are called sulci. deepest sulci is called fissures

The left and right halves are called corpus callosum, made up of two white matter tracts

Cerebrum = frontal, parietal, temporal lobe, temporal lobe, and occipital lobe

a thin layer matter called cerebral cortex, made up of neuron dendrites and cell bodies, forms the surface of. the cerebrum

basal nuclei or basal ganglia, whose functioning is essential for producing automatic movements and postures

Cerebrum = These terms sum up the major cerebral functions: consciousness, thinking, memory, sensations, emotions, and willed

Answer 26

In short =
BRAIN STEM
medulla oblongata = two-way conduction pathway between the spinal cord and higher brain centers; cardiac; respiratory; and vasomotor control center
Pons = two-way conduction pathway between area of the brain and other regions of the body, influences respiration
Midbrain = relay for visual and auditory impulses
CEREBELLUM = muscle coordination maintenance of equilibrium and posture
DIENCEPHALON =
hypothalamus = body temp, water balance , sleep cycle , control, appetite and sexual arousal
Pineal gland = adjust output melanin in response to changes in external light, to keep the bodys internal clock on time
thalamus = sensory relay station from various body areas to the cerebral cortex, emotions, alerting or arousal mechanism

Question 27

Meninges =
by surrounding them with a tough, fluid-cushioned set of membranes called the meninges.

They are the dura mater, which is the tough outer layer that lines the vertebral canal, the pia mater, which is the innermost membrane covering the spinal cord itself, and the arachnoid mater, which is the membrane between the dura and the pia mater.

Fluid fills the subarachnoid spaces between the pia mater and arachnoid in the brain and spinal cord. This fluid is called cerebrospinal fluid (CSF). also fills spaces in the brain called cerebral ventricles

Question 28

PNS
The nerves connecting the brain and spinal cord to other parts of the body constitute the peripheral nervous system (PNS). This system includes cranial nerves and spinal nerves that connect the brain and spinal cord, respectively, to peripheral structures such as the skin surface and the skeletal muscles

12 cranial nerves are attached to the undersurface of the brain

Question 29

olfactory = sense of smell
optic = vision
oculomotor = eye movements
trochlear = eye movements
trigeminal = sensations of face, scalp, and teeth” chewing movements
abducens = eye movements
vestibulocochlear = hearing; sense of balance
glossopharyngeal = sensation of throat, taste, swallowing movements
facial = sense of taste contraction muscles of facial expression
vagus = throat / larynx / thoracic/abdominal orgran / voice productions
accessory = shoulder movements turning of head
hypoglossal = tongue movements

Question 30

Skin surface areas supplied by a single spinal nerve are called dermatomes.

Autonomic nervous system
Cardiac muscle tissue
smooth muscle tissue
glandular muscle tissue

The ANS consists of two divisions called the sympathetic division and the parasympathetic division

Autonomic neurons are the motor neurons that make up the ANS

Their axons extend from these structures and terminate in peripheral “junction boxes” called ganglia.

These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion.

As their name suggests, postganglionic neurons conduct impulses from a ganglion to cardiac muscle, smooth muscle, or glandular epithelial tissue.

Autonomic or visceral effectors are the tissues to which autonomic neurons conduct impulses.

Question 31

Sympathetic preganglionic neurons have dendrites and cell bodies in the gray matter of the thoracic and upper lumbar segments of the spinal cord

Sympathetic postganglionic neurons have dendrites and cell bodies in sympathetic ganglia. Sympathetic ganglia are located in front of and at each side of the spinal column

The sympathetic division functions as an emergency system. Impulses over sympathetic fibres take control of many internal organs when we exercise strenuously and when strong emotions—anger, fear, hate, anxiety—are elicited. In short, when we must cope with stress of any kind, sympathetic impulses increase to many visceral effectors and rapidly produce widespread changes within our bodies.

Question 32

The dendrites and cell bodies of parasympathetic preganglionic neurons are located in the gray matter of the brainstem and the sacral segments of the spinal cord

The dendrites and cell bodies of parasympathetic postganglionic neurons lie in these outlying parasympathetic ganglia, and their short axons extend into the nearby structures

The parasympathetic system dominates control of many visceral effectors under normal, everyday conditions. Im- pulses carried by parasympathetic fibers, for example, tend to slow heartbeat, increase peristalsis, and increase secretion of digestive juices and insulin

Question 33

Autonomic neurotransmitter
= the sympathetic preganglionic axon, the parasympathetic
preganglionic axon, and the parasympathetic postganglionic axon—release acetylcholine (ACh). These axons are therefore classified as cholinergic fibers.

Only one type of autonomic axon releases the neurotrans- mitter norepinephrine (noradrenaline). This is the axon of a sympathetic postganglionic neuron, and such neurons are classified as adrenergic fibers.

Question 34

autonomic nervous system as a whole
= ey are continually influenced directly or indirectly by impulses from neurons located above them, notably by some in the hypothalamus and in the parts of the cerebral cortex called the limbic system or emotional brain.

Question 35

Classification of senses

Answer 35

A. General senses
1. Detected by sensory organs that exist as individual
cells or receptor units (see Table 10-1)
2. Widely distributed throughout the body
B. Special senses (see Table 10-2)
1. Detected by large and complex organs, or localized
grouping of sensory receptors
C. Sensory receptor types
1. Classified by presence or absence of covering capsule a. Encapsulated
b. Unencapsulated (“free” or “naked”)
2. Classified by type of stimuli (mode) required to acti- vate receptors
a. Photoreceptors (light)
b. Chemoreceptors (chemicals)
c. Pain receptors (injury)
d. Thermoreceptors (temperature change)
e. Mechanoreceptors (movement or shape change)

Question 36

Sensory pathways

Answer 36

A. All sense organs have common functional characteristics 1. All are able to detect a particular stimulus
2. A stimulus results in generation of a nerve impulse
3. A nerve impulse is processed and perceived as a sensa-
tion in the central nervous system

Question 37

General senses

Answer 37

A. Distribution is widespread; single-cell receptors are common
B. Mode—the kind of stimulus or change a receptor or sense is able to detect
1. Examples of general sensory receptors and their
modes (see Figure 10-1 and Table 10-1)
a. Free nerve ending—pain, discriminative touch,
tickle, and temperature
b. Bulboid corpuscle (Krause end-bulb)—touch and
possibly cold
c. Lamellar corpuscle (Pacini corpuscle)—pressure
and high-frequency vibration
d. Tactile corpuscle (Meissner corpuscle)—fine touch and low frequency vibration
e. Bulbous corpuscle (Ruffini corpuscle)—touch and pressure
f. Tendon organ (Golgi tendon organ)—proprioception (sense of muscle tension)
g. Muscle spindle—proprioception (sense of muscle length)
2. General sense organs are also found in deep organs of the body

Question 38

special senses

Answer 38

A. Vision
1. Eye (see Figure 10-2)
a. Layers of eyeball
(1) Fibrous layer—tough outer coat
(a) Sclera—“white” of eye
(b) Cornea—transparent part over iris
(c) Conjunctiva—mucous membrane that
covers front of fibrous layer and extends to
inside of eyelids
(d) Lacrimal gland—secretes tears that
moisten conjunctiva
(2) Vascular layer—has dense network of blood
vessels
(a) Choroid—pigmented, melanin-rich layer
prevents scattering of light
(b) Iris—the colored part of the eye; the pupil
is the hole in the center of the iris; con- traction of smooth muscle dilates or con- stricts pupil (see Figure 10-3)
(c) Lens—transparent body behind the pupil; focuses or refracts light rays on the retina
(d) Ciliary muscle—near front of vascular layer, just outside the edge of the iris; con- traction affects shape of lens just behind the iris, thus altering focus for near objects
(3) Inner layer—innermost sensory layer
(a) Retina—contains various kinds of photore-
ceptors (see Figure 10-4 and Figure 10-5)
i. Rods—receptors for night vision and
peripheral vision
ii. Cones—receptors for day vision and
color vision
iii. Ganglion cells—receptors for changing
light patterns of days, months, seasons
b. Eye fluids
(1) Aqueous humour—in the anterior chamber in front of the lens
(2) Vitreous humour—in the posterior chamber behind the lens
2. Visual pathway
a. Vision detects intensity (brightness) and wave-
length (color) of light, as well as images and
motion
b. Light must be refracted (focused) by the eye to form a detectable image

Question 39

c. Innermost layer of retina contains rods and cones
d. Impulse travels from the rods and cones through the bipolar and ganglionic layers of retina (see
Figure 10-4)
e. Nerve impulse leaves the eye through the optic
nerve; the point of exit is free of receptors and is
therefore called a blind spot
f. Visual interpretation occurs in the visual cortex of
the occipital lobe of the cerebrum
B. Hearing and equilibrium
1. The ear functions in hearing and in equilibrium using receptors called mechanoreceptors
2. Ear (see Figure 10-6) a. External ear
(1) Auricle (pinna)
(2) External acoustic canal (see Figure 10-7)
(a) Curving canal 2.5 cm (1 inch) in length (b) Contains ceruminous glands
(c) Ends at the tympanic membrane
b. Middle ear
(1) Houses ear ossicles—malleus, incus, and stapes (2) Ends in the oval window
(3) The auditory tube (eustachian tube) connects
the middle ear to the throat
(4) Inflammation called otitis media
c. Inner ear (see Figure 10-8)
(1) Bony labyrinth filled with perilymph
(2) Subdivided into the vestibule, semicircular
canals, and cochlea
(3) Membranous labyrinth filled with endolymph
3. Hearing (see Figure 10-9)
a. Hearing detects changes in intensity (loudness) and
frequency (tone) of sound waves, which are pres-
sure waves
b. Sound waves are funneled by auricle into external
acoustic canal and vibrate the tympanic membrane
c. Vibrations of tympanic membrane are amplified by
auditory ossicles and transmitted to the oval
window
d. Vibrations of the oval window trigger vibrations of
perilymph, which in turn vibrates the endolymph
e. Sensory hair cells on the spiral organ (organ of
Corti) respond when bent by the movement of sur- rounding endolymph set in motion by sound waves; can become damaged by chronic exposure to loud noise
4. Equilibrium—two types of balance: static and dynamic
a. Static equilibrium—sense of gravity (see
Figure 10-10)
(1) Detected by ciliated hair cells (mechanorecep-
tors) of the two maculae in the vestibule
(2) When the head tilts, gravity pulls the heavy gel
of each macula, bending the sensory cilia and producing a nerve signal

b. Dynamic equilibrium—sense of speed and direc- tion of movement (see Figure 10-11)
(1) Detected by ciliated hair cells (mechanorecep-
tors) of the crista ampullaris (with flaplike cupula) in the ampulla of each semicircular canal
(2) When speed or direction of movement of head changes, the flow of endolymph in semicircular canals is altered, which causes change in bending of sensory cilia (producing a nerve signal)
c. Vestibular nerve carries nerve impulses from the equilibrium receptors of the vestibule; joins with cochlear nerve to form vestibulocochlear nerve (cranial nerve VIII)
C. Taste
1. Sense of taste is also called gustation
2. Receptors are chemoreceptors called gustatory cells,
located in taste buds (see Figure 10-12)
3. Cranial nerves VII and IX carry gustatory impulses 4. Primary taste modes
a. Sweet—detects sugars
b. Sour—detects acids
c. Bitter—detects alkaline solutions d. Salty—detects sodium ions
e. Metallic—detects metal ions
f. Umami (savory)—detects glutamate (an amino acid)

D. Smell
1. Olfactory receptors in olfactory mucosa of nasal cavity
(see Figure 10-13) are extremely sensitive but easily
adapt (become fatigued)
2. Odor-causing chemicals initiate a nerve impulse that
is carried on cranial nerve I and interpreted as a spe-
cific odor by the brain
3. Olfaction has a strong relationship with emotions and
memory through the limbic system E. Integration of senses
1. All senses are processed and finally perceived in the brain (not receptors)
2. Sensory information is combined to form an overall sensory perception of our world
a. Flavor
CHAPTER 10 Senses 227
b.
(1) Combination of gustatory and olfactory senses; can be affected by other senses, such as touch, pain, or temperature
(2) Nasal congestion interferes with stimulation of olfactory receptors and thereby dulls flavor sensations
Posture and balance—both senses of equilibrium with vision and proprioception—combine to help us maintain a safe body position
3. Some sensory information is processed subconsciously
4. Our senses may decline as we age

Answer 39

Free Nerve Endings
The naked nerve ending (several types exist
Location: skin and mucosa (epithelial layers)
Pain, discriminative, touch, tickle, and temperature

Encapsulated Nerve endings
Bulboid corpuscle (Krause
corpuscle)
Location: Skin (dermal layer), subcutaneous tissue, mucosa of lips and eyelids, and external genitals
Touch and possibly cold

Lamellar corpuscle (Pacini
corpuscle)
Location: Subcutaneous, submucous, and subserous tissues; around joints; in mammary glands and external genitals of both sexes
Pressure and high-frequency vibration
Pressure and high-frequency vibration

Tactile corpuscle( meissner corpuscle)
Location: Skin (in papillae of the dermis) fingertips, lips
Fine touch and low-frequency vibration

Bulbous corpuscle (Ruffini
corpuscle)
Location: Skin (dermal layer) and subcutaneous tissue of fingers
Touch and pressure

Tendon organ (golgi organ)
Location: Near the junction of tendons and muscles
Proprioception (sense of muscle tension)

muscle spindle
Location: Skeletal muscles
proprioception (sense of muscle length)

Question 41

ENDOCRINE SYSTEM

Question 42

The endocrine system performs the same general functions as the nervous system: communication and control. The nervous system provides rapid, brief control by way of fast-travelling nerve impulses. The endocrine system provides slower but longer-lasting control by way of hormones (chemicals) secreted into and circulated by the blood.

Question 43

two types of glans in the body
exocrine glands and endocrine glands
only endocrine glands belong to the system.

Endocrine glands are ductless glands. They secrete hormones into intercellular spaces.

a cell that has a specific receptor for that hormone, triggering a reaction in the cell = target cell

production of too much hormone by a diseased gland is called hypersecretion.

if too little hormone is produced, the condition is called hyposecretion.

Mechanism of hormone action
a hormone causes its target cells to respond in particular ways has been the subject of intense interest and research. The two major classes of hormones—nonsteroid hormones and steroid hormones—differ in the mechanisms by which they influence target cells.

Non-steroid hormones
Nonsteroid hormones typically work according to the second messenger mechanism.
thyroid-stimulating hormone acts as a first messenger

After a hormone attaches to its specific receptor site, several chemical reactions occur. These reactions activate molecules within the cell called second messengers.

One example of this mechanism occurs when the hormone-receptor interaction changes energy-rich adenosine triphosphate (ATP) molecules inside the cell into cyclic AMP (adenosine monophosphate).

AMP serves as a second messenger

Question 44

ENDOCRINE GLANDS AND HORMONES FUNCTION

Answer 44

ANTERIOR PITUITARY
TSH = tropic hormone stimulates the secretion of thyroid hormones
Adrenocorticotropic ACTH = tropic hormones stimulate secretion of the adrenal cortex hormones
FSH = tropic hormone
Female = stimulates the development of ovarian follicles and secretion of estrogen
male = stimulates seminiferous tubules of testes to grow and produce sperm
LH = tropic hormone
Female = stimulates maturation of ovarian follicles and ovum stimulates secretions of estrogen, triggers ovulation, stimulates development of corpus luteum
Male = stimulates interstitial cells of the testes to secrete testosterone.
GH = stimulates growth in all organs, and mobilizes nutrient molecules, causing an increase of blood glucose concentration.
PRL = breast development during pregnancy and milk secretion

Question 45

POSTERIOR PITUITARY
antidiuretic ADH = stimulates the retention of water by the kidneys
Oxytocin = uterine contractions at the end of pregnancy
stimulates the release of milk into the breast ducts
HYPOTHALAMUS
Releasing hormones = stimulate the anterior pituitary to release hormones
inhibiting hormones = inhibit the anterior pituitary secretion hormones
THYROID
Thyroxine T4 and triiodothyronine T3 = stimulate the energy metabolism of all cells
Calcitonin = inhibits the breakdown of bones, and causes a decrease in blood calcium concentration
Parathyroid
PTH parathyroid breakdown of the bone; causes an increase in blood calcium concentration.

ADRENAL CORTEX
mineralocorticoids = regular electrolyte and fluid homeostasis
glucocorticoids = stimulate gluconeogenesis. causing an increase in blood glucose concentration also has anti-inflammatory, anti-immunity, and anti-allergic effects.
Androgen = sexual drive in the female but negligible effects in male
The innermost or deepest zone of the cortex secretes small amounts of sex hormones.
Cortisol, or cortisone, is the chief glucocorticoid produced by the adrenal cortex.

ADRENAL MEDULLA
epinephrine (adrenaline and norepinephrine
= prolong and intensify the sympathetic nervous response during stress

Pancreatic Islet
glucagon = liver glycogenolysis causing an increase in blood glucose concentration
insulin = promotes glucose entry into all cells, causing a decrease in blood glucose concentration

Question 46

Ovary
Estrogens = promote development and maintenance of female sexual characteristics
Progesterone = promotes conditions required for pregnancy

Testis
Testosterone = promotes the development and maintenance of male sexual characteristics

Thymus
Thymosins = promote the development of immune system cells

Placenta
Chorionic gonadotropin, estrogen, progesterone =
promote conditions required during early pregnancy

Pineal Gland
Melatonin = inhibits tropic hormones that affect the ovaries and helps regulate the body’s inner clock and sleep cycles

Heart (atria)
atrial natriuretic hormone = regulates fluid and electrolyte homeostasis

Gastrointestinal (GI) Tract
Ghrelin = affects energy balance (metabolism)

Fat storing cells
leptin = controls how hungry or full we feel

Question 47

The regulation of hormone levels in the blood depends primarily on the homeostatic mechanism called negative feedback

Positive feedback mechanisms, which are uncom- mon, amplify changes rather than reverse them.

Question 48

Prostaglandins (PGs), or tissue hormones, are important and extremely powerful lipid substances found in a wide variety of tissues. They modified versions of fatty acids.

Leukotrienes and thromboxane are sometimes called paracrine agents. The term paracrine means “secrete beside”—an apt description for a regulatory agent released right next to its target cell.

It sits securely within a “seat” called the sella turcica, formed by two bony projections at the top of the sphenoid bone.

Pituitary gland
One is called the anterior pituitary gland, or adenohypophysis, and the other is called the posterior pituitary gland, or neurohypophysis.

LH also stimulates the formation of a golden body, the corpus luteum, from the ruptured follicle. This process—called luteinization

Too much insulin in the blood produces hypoglycemia (lower-than-normal blood glucose concentration).

Too much GH produces hyperglycemia (higher-than-normal blood glucose concentration).

Hyposecretion of ADH results in diabetes insipidus, a condition in which large volumes of urine are formed.

excess of cal- cium in the blood, a condition called hypercalcemia, from developing.

Question 49

Pancreatic Islet

Alpha cells secrete a hormone called glucagon, whereas beta cells secrete one of the best-known of all hormones, insulin

Glucagon accelerates a process called glycogenolysis in the liver. Glycogenolysis is a chemical process by which the glucose stored in the liver cells in the form of glycogen is converted to glucose.

Question 50

Where is the blindspot optic nerve
The iris control pupil size
How many cones exist 4
Transparent cornea
Adjust focus lens
Macula functions sharp vision
The cornea is vascular false
Photoreceptor is located at retina
Vitreous body maintains shape
Corneas role in focus light
Cochlea is located inner ear
Semi circular canals. 3
Crista ampularies sensory organs
Proprioception body position sense
Muscle tensions golgi tendon organs
Processes smell information olfactory bulb

Question 51

What does the hypothalamus controls hunger
Glands controls the thyroid pituitary gland
Parathyroid secretes parathyroid hormones
Organs does pth target kidneys
Secretes glucagon alpha
Hormones released during fasting glucagon
Pancreas both endocrine and exocrine true
How steroid hormones enter cells diffusion
Function of aldosterone regulate sodium
Steroid hormones are lipid soluble

Answer 51

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