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Hormones |
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In the
body there are eight major endocrine glands. Every gland secretes
particular hormone.
Hormones are transported in extra cellular fluid to help regulates the
cellular function. It regulates the metabolic function |
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Nervous
system |
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The nervous system is composed of central nervous system and
peripheral nervous system |
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Parts of Brain
and its Function |
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Cerebrum, Cerebellum, and medulla oblongata constitute the
brain. |
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Medulla
oblongata: -
It involves in involuntary functions, such as regulation of
heartbeat, breathing, vasoconstriction, and reflex centers
for vomiting, coughing, sneezing, swallowing, and hiccuping.
Homeostasis of body is maintained by hypothalamus. Thirst,
hunger, body temperature, water balance etc are regulated by
it and also connects the nervous system to endocrine system.
Mid brain and pons also involved in involuntary functions.
The thalamus serves as central relay point for incoming
nervous message. |
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Cerebellum: -
Muscles co- ordination and maintenance of normal muscle tone
and posture is done by cerebellum. Actually it co-ordinate
balance of body |
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Cerebral Hemisphere: -
Sensory and motor functions are regulated by cerebral
hemisphere. Intelligence and reasoning, learning and memory
are governs by it. |
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Spinal Cord: -
Carries message to and away from brain. It also involves in
reflex action. |
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Peripheral
nervous system: -
Consist of nerves, which connect brain and spinal cord to
rest of body.
Cranial nerves: -
Take impulses from body to brain and from brain of body
Spinal nerves: -
They take impulses to, and away from spinal cord. Somatic
nervous system comprises of sensory and motor neuron.
Sensory neuron: -
Sensory receptor detect the state of body or state of
surrounding
Five types of sensory receptor
1)
Mechanical
receptor: -
Detect mechanical deformation of the receptor or of cells
adjacent to the receptor.
2) Thermo
receptor: -
Detect change in temperature like cold and warmth.
3)
Nociceptor: -
Detect damage in the tissue whether it is physical or
chemical damage.
4)
Electromagnetic receptor: -
Detect light on retina of eye.
5) Chemo
receptor: -
Detect taste, smell, oxygen level, osmolality, carbondioxide
concentration, and other
factor that make up chemistry of body. |
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Autonomic nervous system
A large segment of nervous system is called autonomic
nervous system. It operates at a subconscious level and
controls many function of internal organs including action
of heart, movements of gastrointestinal tract and secretion
by different gland and helps in urinary bladder emptying,
sweating, body temperature and many other activities. This
system is activated mainly by centers located in spinal
cord, brainstem, and hypothalamus.
The autonomic signals are transmitted to the body through
two major subdivisions: -
1) Sympathetic
2) Parasympathetic
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Sympathetic nerve fiber:-
Sympathetic nerve originates in
spinal cord between the segment T1 and L2 and pass first
in to sympathetic chain then in to the tissue and organ.
Sympathetic nerve fibres in skeletal nerves control the
blood vessels, sweat glands, and pilo erector muscle.
The sympathetic pathway originating in different
segments of the spinal cord are not necessarily
distributed to the same parts of the body as spinal
nerves fibres from the same segment. Instead the
sympathetic fibres From T1 goes to
head
From T2 goes to neck
From T3 T4 T5 T6 goes to thorax
From T7 T8 T9 T10 T11 goes to abdomen
From T12 L1 L2 goes to legs
This distribution is only
approximate and overlaps generally.
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Parasympathetic nerve fibre:
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Parasympathetic nerve fibre
originates from central nervous system through several
cranial nerves, second and third spinal nerves, and
occasionally the first and fourth sacral nerves. Almost
75% of parasympathetic nerves are in the vagus nerve
distributed in entire thoracic and abdominal regions of
the body. Parasympathetic nerve in third nerve goes to
papillary sphincters and ciliary muscles of eye. Seventh
nerve fibres passes to lacrimal and sub mandibular
glands and fibres from ninth nerve pass to the parotid
gland.
The sacral parasympathetic fibres congregate are called
pelvic nerves, leaves the sacral plexus on each side of
cord and distribute their fibres to descending colon,
rectum, bladder and lower portions of ureters. Also this
group of parasympathetic supplies fibres to external
genitalia.
Functions of sympathetic and
parasympathetic nerves fibres: -
Acetylcholine and adrenaline are two
types of synaptic transmitters are there secreted by
nerve endings of parasympathetic and sympathetic nerve
fibres. Those fibres, which secrete acetylcholine, are
called cholinergic. Those fibres, which secrete
adrenaline or norepinephrine, are called adrenergic.
Preganglionic neurons of both parasympathetic and
sympathetic fibres are cholinergic. Therefore,
acetylcholine when applied to ganglia will excite
postganglionic neurons of parasympathetic and
sympathetic nerve fibres. The postganglionic neuron of
parasympathetic fibres secretes acetylcholine. It means
they are cholinergic. While most of postganglionic
neurons of sympathetic fibres are adrenergic, through
sympathetic nerve fibres to the sweat glands, pilo
erector muscles and few blood vessels are cholinergic.
Those hormones act on different organs to cause the
respective parasympathetic and sympathetic effect.
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Circulatory system: -
The circulatory system is a continuous system like closed
circuit.
The circulation of blood in body is by two ways
A. Pulmonary circulation
B. Systemic circulation
A)
Pulmonary circulation: -
Due to the contraction of right ventricle of heart, blood
pumps out from right ventricle to pulmonary artery, this
opens in the lungs. Gaseous exchange takes place in lungs.
Then the oxygenated blood through Pulmonary veins enters in
left atrium of the heart.
B)
Systemic circulation: -
Oxygenated blood from left atrium goes in to left ventricle.
Left atrium, on contraction, pumps the blood in to left
ventricle through martial valve. Then the left atrium
relaxed and left ventricle contracts and pumps the blood in
to the aorta that divided in to different arteries. Arteries
distributed the blood to different parts of the organs and
there they divided in to arterioles and then in to
capillaries.
The
functional part: -
Arteries: - They transport blood under high pressure to
tissue. They are made up of strong vascular walls. Blood
flows rapidly in the arteries.
Arterioles: - Arterioles have strong muscular walls, that is
capable of closing the arterioles completely or allow it to
be dilate several folds. Arterioles have capability of
altering blood flow to the capillaries. Arterioles are last
small branches of arterial system through which blood is
released in to capillaries.
Capillaries: - Capillaries walls are very thin and are
permeable to small molecular substances, their function is
to exchange fluid, nutrients electrolyte, hormone and other
substance between blood and interstitial spaces.
Venules: - They collect blood from capillaries and gradually
coalesce in to progressively larger veins.
Veins: - They transport blood from tissues back to heart.
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Lymphatic
Lymphatic system is a necessary route by which fluid can
flow from interstitial spaces in to the blood. They carry
proteins of high molecules and large particulate matter away
from tissue spaces, which are not removed by absorption
directly in to the blood capillaries. This removal is an
absolutely essential function without which we would die in
24 hrs.
Lymph is derived from interstitial fluid
that flows in to the lymphatic.
Factors determine rate of lymph flow
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Interstitial fluid pressure
Elevation of Interstitial free fluid pressure above
its normal level (-5.3mm of Hg) results in increase in
flow of interstitial fliud in to lymphatics capillaries.
Thus increase rate of lymph flow. The factors
responsible for elevation in lymphatic pressure are
1.
Elevated capillary pressure.
2. Decrease plasma colloid osmotic pressure.
3. Increase interstitial fluid protein.
4. Increase permeability of capillaries.
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Lymphatic Pump
1. Intrinsic pumping.
2. Extrinsic pumping.
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Lymphatic capillary pump.
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Core temperature
Core
temperature is deep tissue temperature. It tries to remain
almost exactly constant. While surface temperature of body
rises and fall with surface temperature. |
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Skin
Skin consist of three layers
1. Epidermis: -
Uppermost layer forming the surface of skin made up of cells
called keratinocytes, melanocytes and langerhan cells are
another important feature of epidermis.
This layer is useful for protection and pigmentation.
2. Dermis: -
This is a dense connective tissue, which is responsible for
pliability and mechanical resistance, and regulation of body
temperature It contains
1. Blood
vessels: - It supplies nutrition and oxygen to cells of skin
helps in Thermoregulation.
2. Meissner's corpuscles: - These are touch receptor.
Detects light touch and soft.
3. Pacinians corpuscles :- These are receptor for deep
pressure and vibration.
4. Free nerve endings: - They are sensitive to pain,
temperature changes and itchiness.
5. Nerves fibers: - They forward the information.
6. Sebaceous gland: - It secretes oily substance called
sebum, which is a natural moisturizer that conditions the
hair and skin.
7. Sweat glands: - These are sweat producing structures
involved in thermoregulation they excretes some salts like
ammonia and metabolic by products.
8. Hair follicles :- They helps in closing up of skin pores
and keeping the warmth in.
9. Lymphatic vessels: - They help to protect the body
against foreign invaders or infections.
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Hypodermis: -
Hypodermis: - Hypodermis strongly impacts the skin to the
body but allows its restricted movements. It provides the
protective cushion and insulates the body. |
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