Physiology 214
INTRODUCTION TO PHYSIOLOGY AND HOMEOSTASIS
Physiology: study of the function of living things & how the human body works
Mechanisms of action: cause and effect/change sequences of physical & chemical processes
Explanation of events in the body: purpose of a body process and underlying mechanism
(initiated and regulated)
What? Shivering in response to cold
Why? Generates heat to warm body
How it is carried out? Temperate sensitive nerve cells detect a decrease in body temperate
by peripheral thermoreceptors in the skin - signal a region in the brain responsible for
temperature sensitivity at the hypothalamic centres for thermoregulations (body’s
thermostat) - activates nerve pathway causing involuntary oscillating waves of muscle
contraction (shivering) by motor neurons, skeletal muscles, muscle tone and shivering
Negative/positive feedback?
Structure and function inseparable: air sacs (alveolus) in lungs contain thin walls (one cell
thick wall) closely associated with blood vessels (network of capillaries) for diffusion of gases
between the lungs and blood to be efficient and time effective
Processes can be unconscious:
▪ Eyes convert images into electrical signals/nerve impulses transmitting information to the brain
▪ Blood cells die and are replaced consistently by newly produced ones
▪ Heart pumps litres of blood through the lungs and the body
▪ Blood flows through kidneys acting on the blood to conserve materials and eliminate waste in urine
▪ Digestive system processes meals for transfer into the bloodstream for delivery to cell
▪ Brain provides output to muscles to maintain posture, eye movement and chemical messengers carry
signals between nerves and muscles to trigger muscle contractions
▪ Consistent breathing exchanging air between atmosphere and lungs
▪ Cells consumes oxygen and produce carbon dioxide
▪ Body uses calories of energy from food to support life and contracting muscles burn added calories
Levels of organisation in the body
1. Chemical level: molecules making components in membrane that encloses the cell
Various atoms and molecules make up the body
Atoms = smallest building blocks of matter (O, C, N & H)
Molecules = atoms combine to make larger molecules
Form carbohydrates and proteins
2. Cellular level: cell in stomach lining
Cells are basic unit of life that is the smallest unit capable of carrying out basic processes
Functional units enclosed by a plasma membrane
Interior composition regulated containing atoms and molecules used, produced and
maintained for functions
, Physiology 214
Inside membrane is intracellular and outside membrane is extracellular with exchanged
between
Basic cell functions
▪ Obtaining food/nutrients (amino acids to build proteins) and oxygen
▪ Performing chemical reactions breaking down nutrients for building blocks
o Wastes generated
▪ Eliminating carbon dioxide and other waste
▪ Synthesising proteins from broken down material
▪ Controlling exchange of material in and out as well as the quantity
▪ Moving material internally from one part of cell to the other
▪ Sense and respond to environment when deficiency in nutrients/oxygen
▪ Reproduce by dividing and replication
Specialised cell functions and activities
▪ Digestive glands use protein synthesise to produce digestive enzyme which are
specialised proteins breaking down food (specific to glands)
o Function - protein synthesis
▪ Kidney tubules regulate substances between blood on one side of cell and urine on
the other to filter waste and selectively retain required matter
o Function - control exchange
3. Tissue level: layers of tissue in stomach wall from similar cells
Groups of cells of similar specialisation with 4 primary tissue types
Muscle tissue consists of cells specialised for contracting generating tension and producing
movement
▪ Skeletal muscles moves the skeleton - voluntary & striated
▪ Cardiac muscle pumps the blood out the heart - involuntary & striated
▪ Smooth muscle controls movement of content through hollow tubes and organs
(movement of food in digestive tract) - involuntary & striated
▪ Function - movement
Nervous tissue consists of cell specialised for initiation and transmitting electrical
impulses
▪ Electrical impulses act as signals that relay information from 1 part to another
▪ Found in the brain, spinal cord, nerves and special sense organs
▪ Function - muscle coordination, communication and control
, Physiology 214
Epithelial tissue consist of cells specialised for exchanging materials between
cell/environment
▪ Epithelial sheets - layers of tightly joined cells that cover & line parts of the body
o Selective transfer of material between regions separated by epithelial barrier
▪ Secretory glands - epithelial tissue derivatives specialised for secreting
o Formed by pockets of epithelial tissue that dip inwards from the surface and
develop secretory capabilities
o Secretion: release from a cell in response to a stimulation of specific products
produced by the cell
o Exocrine and endocrine glands
▪ Function - protective layer, secretion of gastric enzymes and absorption
Connective tissue has few cells dispersed within an abundance of extracellular material
▪ Connects, supports and anchors body parts
▪ Cells within connective tissue produce specific structural molecules and release it
into extracellular spaces between cells
▪ Function - mechanical/structural support
4. Organ level: stomach from similar tissues
Organ is a body structure that integrates different tissues carrying out a specific function
Organ consists of 2/more of the types of primary tissue organised to perform functions
▪ Stomach lined with epithelial tissue and epithelial gland cells (exocrine and
endocrine cells), stomach wall contains smooth muscle tissue, nervous tissue and
connective tissue binds all the tissues
5. Organ/body system level: digestive system from many organs
Collection of related organs interacting for specific body functions
, Physiology 214
▪ Circulatory - heart, blood vessels and blood
▪ Digestive - mouth, pharynx, oesophagus, stomach, small intestine, large intestine,
salivary glands, exocrine pancreas, liver and gall bladder
▪ Respiratory - nose, pharynx, larynx, trachea, bronchi and lungs
▪ Urinary - kidneys, uterus, urinary bladder and urethra
▪ Skeletal - bones, cartilage and joints
▪ Muscular - skeletal muscles
▪ Integumentary - skin, hair and nails
▪ Immune - lymph nodes, thymus, bone marrow, tonsils, adenoids, spleen,
appendix, white blood cells, gut and skin associated lymphoid tissue
▪ Nervous - brain, spinal cord, peripheral nerves and special sense organs
▪ Endocrine - hormone secreting tissues, hypothalamus, pituitary, thyroid,
adrenals, endocrine pancreas, gonads, kidneys, pineal, thymus, parathyroids,
intestine, heart, skin and adipose tissue
▪ Reproductive - testes, penis, prostate gland, seminal vesicles, bulbourethral
glands and associated ducts; ovaries, oviducts, uterus, vagina and breasts
6. Organism level: whole body packaged with a complete set of all the body systems
Body systems depend on proper functioning of other systems to carry responsibilities
Whole body of multicellular organism = various body systems structurally and
functionally linked therefore different body systems so not act in isolation
Homeostasis
▪ Ability to maintain stable internal conditions despite changes in internal/external
environment & considered as a small range within narrow limits of internal
conditions balanced within the body as a whole to achieve a steady state (pH)
▪ Dynamic process of continued adjustments to maintain internal conditions in
response to continued external changes to sustain fluctuations in a threshold
o Not rigid & fixed state but dynamic & steady state where changes that occur
are minimised by compensatory physiological responses
▪ Homeostasis - stimulus from imbalance - change detected - receptor - input sent via
afferent pathway to control centre - output sent via efference pathway to effector -
response to change - homeostasis with imbalance corrected = normal
▪ Functions of the systems contribute to homeostasis therefore maintaining within the
body the environment needed for functionality of cells & cells make up body systems
▪ Homeostasis is essential for survival of each cell & each cell with specialised activities
as part of body systems helps maintain internal environment shared by all cells
▪ Internal environment kept stable as changes in external and internal factors
continuously disrupts homeostasis
External, internal and cellular environments
▪ Internal environment: intracellular fluid surrounding & in cells making exchanges
with ECF then the external environment (cell membrane separates cells from ECF)
INTRODUCTION TO PHYSIOLOGY AND HOMEOSTASIS
Physiology: study of the function of living things & how the human body works
Mechanisms of action: cause and effect/change sequences of physical & chemical processes
Explanation of events in the body: purpose of a body process and underlying mechanism
(initiated and regulated)
What? Shivering in response to cold
Why? Generates heat to warm body
How it is carried out? Temperate sensitive nerve cells detect a decrease in body temperate
by peripheral thermoreceptors in the skin - signal a region in the brain responsible for
temperature sensitivity at the hypothalamic centres for thermoregulations (body’s
thermostat) - activates nerve pathway causing involuntary oscillating waves of muscle
contraction (shivering) by motor neurons, skeletal muscles, muscle tone and shivering
Negative/positive feedback?
Structure and function inseparable: air sacs (alveolus) in lungs contain thin walls (one cell
thick wall) closely associated with blood vessels (network of capillaries) for diffusion of gases
between the lungs and blood to be efficient and time effective
Processes can be unconscious:
▪ Eyes convert images into electrical signals/nerve impulses transmitting information to the brain
▪ Blood cells die and are replaced consistently by newly produced ones
▪ Heart pumps litres of blood through the lungs and the body
▪ Blood flows through kidneys acting on the blood to conserve materials and eliminate waste in urine
▪ Digestive system processes meals for transfer into the bloodstream for delivery to cell
▪ Brain provides output to muscles to maintain posture, eye movement and chemical messengers carry
signals between nerves and muscles to trigger muscle contractions
▪ Consistent breathing exchanging air between atmosphere and lungs
▪ Cells consumes oxygen and produce carbon dioxide
▪ Body uses calories of energy from food to support life and contracting muscles burn added calories
Levels of organisation in the body
1. Chemical level: molecules making components in membrane that encloses the cell
Various atoms and molecules make up the body
Atoms = smallest building blocks of matter (O, C, N & H)
Molecules = atoms combine to make larger molecules
Form carbohydrates and proteins
2. Cellular level: cell in stomach lining
Cells are basic unit of life that is the smallest unit capable of carrying out basic processes
Functional units enclosed by a plasma membrane
Interior composition regulated containing atoms and molecules used, produced and
maintained for functions
, Physiology 214
Inside membrane is intracellular and outside membrane is extracellular with exchanged
between
Basic cell functions
▪ Obtaining food/nutrients (amino acids to build proteins) and oxygen
▪ Performing chemical reactions breaking down nutrients for building blocks
o Wastes generated
▪ Eliminating carbon dioxide and other waste
▪ Synthesising proteins from broken down material
▪ Controlling exchange of material in and out as well as the quantity
▪ Moving material internally from one part of cell to the other
▪ Sense and respond to environment when deficiency in nutrients/oxygen
▪ Reproduce by dividing and replication
Specialised cell functions and activities
▪ Digestive glands use protein synthesise to produce digestive enzyme which are
specialised proteins breaking down food (specific to glands)
o Function - protein synthesis
▪ Kidney tubules regulate substances between blood on one side of cell and urine on
the other to filter waste and selectively retain required matter
o Function - control exchange
3. Tissue level: layers of tissue in stomach wall from similar cells
Groups of cells of similar specialisation with 4 primary tissue types
Muscle tissue consists of cells specialised for contracting generating tension and producing
movement
▪ Skeletal muscles moves the skeleton - voluntary & striated
▪ Cardiac muscle pumps the blood out the heart - involuntary & striated
▪ Smooth muscle controls movement of content through hollow tubes and organs
(movement of food in digestive tract) - involuntary & striated
▪ Function - movement
Nervous tissue consists of cell specialised for initiation and transmitting electrical
impulses
▪ Electrical impulses act as signals that relay information from 1 part to another
▪ Found in the brain, spinal cord, nerves and special sense organs
▪ Function - muscle coordination, communication and control
, Physiology 214
Epithelial tissue consist of cells specialised for exchanging materials between
cell/environment
▪ Epithelial sheets - layers of tightly joined cells that cover & line parts of the body
o Selective transfer of material between regions separated by epithelial barrier
▪ Secretory glands - epithelial tissue derivatives specialised for secreting
o Formed by pockets of epithelial tissue that dip inwards from the surface and
develop secretory capabilities
o Secretion: release from a cell in response to a stimulation of specific products
produced by the cell
o Exocrine and endocrine glands
▪ Function - protective layer, secretion of gastric enzymes and absorption
Connective tissue has few cells dispersed within an abundance of extracellular material
▪ Connects, supports and anchors body parts
▪ Cells within connective tissue produce specific structural molecules and release it
into extracellular spaces between cells
▪ Function - mechanical/structural support
4. Organ level: stomach from similar tissues
Organ is a body structure that integrates different tissues carrying out a specific function
Organ consists of 2/more of the types of primary tissue organised to perform functions
▪ Stomach lined with epithelial tissue and epithelial gland cells (exocrine and
endocrine cells), stomach wall contains smooth muscle tissue, nervous tissue and
connective tissue binds all the tissues
5. Organ/body system level: digestive system from many organs
Collection of related organs interacting for specific body functions
, Physiology 214
▪ Circulatory - heart, blood vessels and blood
▪ Digestive - mouth, pharynx, oesophagus, stomach, small intestine, large intestine,
salivary glands, exocrine pancreas, liver and gall bladder
▪ Respiratory - nose, pharynx, larynx, trachea, bronchi and lungs
▪ Urinary - kidneys, uterus, urinary bladder and urethra
▪ Skeletal - bones, cartilage and joints
▪ Muscular - skeletal muscles
▪ Integumentary - skin, hair and nails
▪ Immune - lymph nodes, thymus, bone marrow, tonsils, adenoids, spleen,
appendix, white blood cells, gut and skin associated lymphoid tissue
▪ Nervous - brain, spinal cord, peripheral nerves and special sense organs
▪ Endocrine - hormone secreting tissues, hypothalamus, pituitary, thyroid,
adrenals, endocrine pancreas, gonads, kidneys, pineal, thymus, parathyroids,
intestine, heart, skin and adipose tissue
▪ Reproductive - testes, penis, prostate gland, seminal vesicles, bulbourethral
glands and associated ducts; ovaries, oviducts, uterus, vagina and breasts
6. Organism level: whole body packaged with a complete set of all the body systems
Body systems depend on proper functioning of other systems to carry responsibilities
Whole body of multicellular organism = various body systems structurally and
functionally linked therefore different body systems so not act in isolation
Homeostasis
▪ Ability to maintain stable internal conditions despite changes in internal/external
environment & considered as a small range within narrow limits of internal
conditions balanced within the body as a whole to achieve a steady state (pH)
▪ Dynamic process of continued adjustments to maintain internal conditions in
response to continued external changes to sustain fluctuations in a threshold
o Not rigid & fixed state but dynamic & steady state where changes that occur
are minimised by compensatory physiological responses
▪ Homeostasis - stimulus from imbalance - change detected - receptor - input sent via
afferent pathway to control centre - output sent via efference pathway to effector -
response to change - homeostasis with imbalance corrected = normal
▪ Functions of the systems contribute to homeostasis therefore maintaining within the
body the environment needed for functionality of cells & cells make up body systems
▪ Homeostasis is essential for survival of each cell & each cell with specialised activities
as part of body systems helps maintain internal environment shared by all cells
▪ Internal environment kept stable as changes in external and internal factors
continuously disrupts homeostasis
External, internal and cellular environments
▪ Internal environment: intracellular fluid surrounding & in cells making exchanges
with ECF then the external environment (cell membrane separates cells from ECF)
