physiology topic function of skin,hair, gland

1. FUNCTIONS OF THEFUNCTIONS OF THE
SKIN, HAIR, GLANDS,SKIN, HAIR, GLANDS,
AND NAILS.BODYAND NAILS.BODY
TEMERATURE AND ITSTEMERATURE AND ITS
REGULATIONREGULATION
BY TOOBA IMRAN

2. SKINSKIN
It is the limiting membrane. Between
body & environment.
Skin is the largest organ of the body.
Has surface area of about 1.5-2m2.
It contain accessory structures: glands,
hairs and nails

3. Body surface areaBody surface area

4. STRUCTURE OF SKINSTRUCTURE OF SKIN
EPIDERMIS (superficial layer)
DERMIS (deeper layer)
HYPODERMIS
(subcutaneous
Layer for fat
Storage).

5. FUNCTIONSFUNCTIONS
1. Water balance
2. Excretion of salt and metabolities
3. Regulation of body temperature
4. General sensation, e.g. touch, pain,
temp. etc.
5. Acid base balance
6. Synthesis of vitamin D
7. Secretion of sweat, sebum

6. FUNCTIONSFUNCTIONS
 Storage of:
1. Fats
2. Salts
3. Glucose
4. Water, etc.
 Protect from external injury and
bacterial invasion.
 Absorption.

7. Water balance:
By perspiration
(sweating)
1
EXCRETION:
it is minor excretory organ
Excrete water and salt as
sweat.
NaCl in sweat ; excessive
sweating may lead to low blood
sodium levels (hyponatraemia).
Urea when kidney function is
lost.
2
REGULATION OF
BODY TEMPERATURE:
Vasoconstriction
Vasodilatation
Sweat production
SENSATIONS:
Sensory receptors (nerve
endings) in the skin that are
sensitive to touch, pressure,
temperature, pain. Stimulus come
nerve impulse generate
transmitted to cerebral cortex.
4
3

8. SYNTHESIS OF
VITAMIN D:
7-dehydrochlestrol
is a lipid-based
substance in the
skin and is
converted to vitamin
D by sunlight.
Protection:
Skin is a waterproof layer.
Protect from micro-organism,
chemicals, physical agents, e.g.
mild trauma, ultravoilet light,
dehydration.
Melanin protect against UV rays.
•Epidermis has immune cells
(langerhans) type of macrophages.
ABSOPTION:
SOME DRUGS, in transdermal
patches, e.g. hormone
replacement therapy during the
menopause, nicotine as an aid to
smoking cessation.
Some toxic chemicals, e.g.
mercury.

9. ACID AND BASE
BALANCE:
The normal skin
surface is acidic due
to lactic acid, fatty
acid, acetic acid
present in sweat and
sebum.
Also the keratin layer
is itself acidic.

10. GLANDSGLANDS
1. SWEAT GLANDS
2. SEBACEOUS GLANDS
3. CERUMINAL GLANDS

11. SWEAT GLANDSWEAT GLAND
SWEAT
It is active secretion of sweat gland.
EXPLANATION:
They are widely distributed through the
skin and are most numerous in palms,
soles, axillae and groin.
The bodies of the glands lie coiled in
subcutaneous tissue.

12. ACCLIMATIZATION OFACCLIMATIZATION OF
SWEATING MECHANISMSWEATING MECHANISM
Normal person produce 700 ml sweat/hr.
But when exposed to hot weather
sweating capability increase to 1.5-2lit/hr.
This is called acclimatization of sweating.
IMPORTANCE
Increase sweating in hot weather removes
excess heat from body.
Conserve Na in body due to inc. secretion
of aldosterone.

13. Types of sweat glandTypes of sweat gland
ECCRINE SWEAT GLAND
•LOCATION:
Everywhere with some
exception (e.g. glans penis)
•SITE OF OPENING
skin surface
•DISCHARGE
Watery, little protein,
mainly water, NaCl,
urea,NH3,& uric acid,.
•INNERVATION
Cholinergic.
APOCRINE SWEAT GLAND
•LOCATION
Axillary, areolar and anal
region
•SITE OF OPENING
Hair follicles
•DISCHARGE
Viscous, odor producing
•INNERVATION
adrenergic

14. Kinds of sweatingKinds of sweating
1. Thermal or hot sweating, due to rise of
external temperature or fever.
2. Emotional or mental or cold sweating;
due to direct stimulation of sweat center
from higher centers in emotional states.
3. Gustatory sweating; due to stimulation
of pain nerve endings in mouth by spicy
food.

15. RELATED TERMSRELATED TERMS
HYPERHIDROSIS:
Increase sweating.
HYPOHIDROSIS:
decrease sweating.
ANHIDROSIS:
abnormal deficiency of sweating.

16. FUNCTIONS OF SWEATFUNCTIONS OF SWEAT
Heat regulation, water balance
Salt balance
Excretion
To keep skin moist and prevent it from
drying.
some drugs and toxins are excreted in
sweat
Acidic nature inhibit bacterial growth.

17. Sebaceous glandsSebaceous glands
These are pear shaped bodies opening
into roots of hair follicles.
They secretes an oily antimicrobial
substance, sebum into the hair follicles.

18. Functions of sebumFunctions of sebum
Act as bacteriostatic agent; so, inhibits
bacterial growth.
Act as lubricant
Prevents damage of epidermis during hot
season
Conserves heat during cold season
Conserve water

19. FunctionsFunctions
Sebum keeps the hair soft and give it a
shiny appearance.
Acne production.
Collect dirt.

20. CERUMINAL GLANDSCERUMINAL GLANDS
Cerumen is a yellow, pasty substance
secreted by ceruminal glands of external
auditory canal.
NOTE:NOTE:
accumulation of cerumen deep
In auditory canal may interfere with
hearing.