AS 211 - INTRODUCTION TO ANIMAL SCIENCE

MODULE 2
Module No. & Title Module 2: ANATOMY AND PHYSIOLOGY I

Module Overview Animal Science students need to have a firm grasp of the
normal structure of an animal’s body and how it functions
before they can develop the best possible ways of maintaining
a healthy and productive herd or flock. Familiarization can help
prevent the occurrence of diseases and injuries.

This module describes the structure of the animal’s body and

the way in which it works. Animals encountered in normal
animal husbandry practice are used as examples whenever
possible. The module is divided into six lessons.

Module Upon completion of this module, you must be able to:

Objectives/Outcomes  Identify the different parts of an organ system both internal
and external
 Interrelate the functions of the different organs system
 Discuss the regulatory role of the nervous and endocrine
system to the function of other organ systems
Lessons in the Lesson 1: The Integumentary System
module Lesson 2: The Skeletal System
Lesson 3: The Muscular System
Lesson 4: The Nervous System
Lesson 5: The Cardiovascular System
Lesson 6: The Respiratory System

Module No. Module 2: Anatomy and Physiology I

and Title
Lesson No. Lesson 1. The Integumentary System
and Title
Learning At the end of this lesson, you must be able to:
Outcomes  Explain the function of the skin and its appendages
 Discuss the significance of the skin and its appendages in the
identification and classification of the animals as well as in the
determination of its health status

Time Frame 1.5 hours

Introduction The food that we eat usually comes from domesticated animals raised
for their meat, egg, and milk. To be able to produce them in large
numbers, cattle, pigs, goats, sheep, chicken, etc. should be well-cared
and should remain healthy and productive. The skin is one of the first
systems affected when an animal becomes sick so it is important for

22
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
anyone working with animals to have a sound knowledge of the
structure and functioning of the skin so they can quickly recognize
signs of disease.

Activity
Match the Horse!
Let see if you can match the color of the horse with the pictures shown
below. Write the letter that corresponds to your answer inside the box.
a. Palomino b. Bay c. Appaloosa d. Dapple gray

Analysis  What makes the animal differ in their skin coloring?

 What do you think is the importance of skin color and

markings in determining the identity of the animal?

The Integumentary System

Abstraction
Integumentary System is composed of the skin and many different
tissue modifications such as the hair, horn, feather, etc. are, in fact,
the largest organ of the body. It performs many functions that are
important in maintaining homeostasis in the body.

Dermatology – the study of the integumentary system

Functions of Skin
a. Protection of sensitive tissues
b. Prevents the penetration of toxic liquids and gases
c. Protects the body from the adverse effects of light.
d. Regulates body temperature
e. Contains ergosterol which helps form vitamin d.

23
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
f. An organ of touch, heat, and pain
g. Prevents delicate tissues from dying

Significance of the Skin

a. Identification of the sex, breed, class, type, or species of
the animal
b. The basis for selection, judging, and culling
c. The basis for buying and marketing stocks
d. The basis on the determination of the animal’s condition
whether it is healthy (shiny and smooth) or not (dull and
rough).

Layers of Skin
a. Epidermis or cuticle
- outer layer and
composed of
stratified epithelial
cells of varying
thickness, devoid of
blood vessels
b. Dermis or corium -
with blood vessels,
nerves, hair
follicles, muscle
fibers and glands Fig. 1. Layers of the skin

Glands of the Skin Sweat or sudoriferous glands

- Eliminates body wastes in a form of sweat and cools off the
body
- Horse sweat on their body; pigs in their snout; and carabao on
their muzzle
a. Sebaceous glands
- Secrets oily substances (sebum) that lubricates hair and skin;
lessens evaporation of water from the body, and contains a
precursor of vit. D

Cerumen – a kind of sebum in the ear (wax) that discourages insects

and prevents the passage of foreign bodies into the ear

Subcutaneous Tissue—also called the superficial fascia; consist of

areolar tissue and adipose tissue that connect the skin to muscles

Appendages of the Skin

a. Hoof - horny covering of the distal and the digit
- Cloven hooves (e.g. cattle, carabao, goat, etc.)

24
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
- Solid hooves (e.g. horse and some swine)
b. Horns - encloses the horn processes of the frontal bone
c. Hair
- the general surface covering of the animal body
- function in identification through its color/shades of color
- Cowlicks are hair on the body of the animal that converges
to form hair streams and vortices that is used as requisites
in the registration of large animals
- has adaptive functions relative to the temperature
regulation of the animal body
- Arrector pili muscle is a small muscle that makes the hair
“stand up” when the animal is frightened or cold
- Hair color - due to the pigment melanin (cortex):
pheomelanin and eumelanin
• Pheomelanin – iron-rich pigment colors hair that gives
hair a yellow-blonde to red shades
• Eumelanin – determine darkness of the hair
subtypes: black and brown eumelanin
o Blond - less concentration of brown eumelanin
o Brown - more concentration of brown
eumelanin
o Gray - less concentration of black eumelanin
o Black - more concentration of black eumelanin

List down at least 10 breeds of cattle, swine, goat, and chicken with
Application their distinguishing physical features.

What a good start! Hope you have gain insights on the importance of
Closure knowing the integumentary system. This is just the beginning of the
exploration of the wonderful structure of the body. Be prepared as we
further discover the next organ system which is the skeletal system.

Module No. Module 2: Anatomy and Physiology I

and Title
Lesson No. Lesson 2. The Skeletal System
and Title
Learning
Outcomes After completing this lesson, you are expected to:
 Identify the parts of the skeletal system
 Discuss the bone functions and processes of bone formation
 Differentiate the types of fractures
1.5 hours
Introduction Imagine if you do not have bones in your body, will you be able to stand,
walk, run, jump, or do any of the usual activities that you are accustomed
to? Without the skeleton, our body would be much like a jellyfish that is
out of the water. Let us explore the skeletal system in Lesson 2.

Activity Direction: 25
Complete the bone-
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
word puzzle by
filling in the boxes
with letters forming
the name of the
bones described
Osteology by of the bones which collectively make up the
- the study
skeleton

Divisions of the Skeleton

a. Axial skeleton - includes the skull, spinal column, or vertebrae
(cervical, thoracic, lumbar, sacral, and caudal/coccygeal), and
ribs.
b. Appendicular skeleton - includes the appendages (forelimb and
hindlimb), pelvic girdle, and shoulder girdle.
c. Visceral skeleton – consists of bones that developed in soft
tissues of certain organs – os rostri (snout in pig); os cordis
( heart of cattle and sheep); os penis (penis in dog)

Classification of Bones
a. Long bones - elongated, cylindrical form with two enlarged
extremities; function as lever and aids in locomotion and
prehension
Examples: Femur, Humerus, Radius, Ulna, Tibia
b. Short bones - equal dimension in length, width,
and thickness; helps in absorbing concussion
Example: Carpus and Tarsus
c. Flat bones - expanded in two directions and are thin;
protects vital organs and serves as an attachment for muscles
Example: Bones of the skull, scapula, and Pelvic bones
d. Irregular bones - unpaired, irregularly shaped and located in
the median plane; protect and support and serves for muscle
attachment
Example: Vertebrae
e. Sesamoid bones – developed along the course of tendons; help
diminish the impact of friction or change the course of
tendons Example: Patella
f. Pneumatic Bones – the presence of air spaces or sinuses that
communicate with the exterior
Example: present in flying birds; maxillary and frontal bones

27
26
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

Source: https://training.seer.cancer.gov/anatomy/skeletal/classification.html

Fig. 2. Parts of a long bone

Functions of Bones
a. Protection of vital organs
b. Gives rigidity and form to the body
c. Acts as levers
d. Storage of minerals
e. Site for blood formation

Osteoblasts - bone-producing cells

Osteoclasts - bone-destroying cells
bb
Osteogenesis - the process by which bone is formed through the
secretory activity of the osteoblasts. In the embryo, it occurs in two
ways:
a. Intramembranous Ossification: bone develops in pre-existing
mesenchymal connective tissue (bones of this type are called
membrane bones)
b. Endochondral Ossification: bones that developed from pre-
existing cartilage (e.g. long bones like femur and humerus).
This type of bone growth is responsible for the longitudinal
growth of bones

Epiphyseal Plate (Epiphyseal Line) - site of bone growth as seen in long

bones. Composed of different zones:
a. zone of growth
b. zone of cartilage transformation
c. zone of ossification

Connective Tissues - the tissue that connects, supports, binds, or 28

separates other tissues or organs, typically having relatively few cells
embedded in an amorphous matrix, often with collagen or other fibers,
and including cartilaginous, fatty, and elastic tissues.
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

Four forms of connective tissue that are found in vertebrate

endoskeletons:
1. Bone: The main structural tissue found in most vertebrates. In
addition to forming the skeletal framework, bones are the site of
blood cell production.
2. Cartilage: Padding for joints in most vertebrates, and the main
structural tissue for some aquatic organisms that do not
possess bones, such as sharks.
3. Tendons: Tissue that joins bone to the muscle.
4. Ligaments: Tissue that connects bones

D. Structure of Bones
Consists of an external shell of dense compact substance, within
which is the more loosely arranged spongy substance and having two
membranes:
a. Periosteum - invests the outer surface of the bone
b. Endosteum - a thin fibrous membrane which lines the medullary
cavity

Fracture of Bones
Fracture – a break in the continuity of the bone
Types of Fractures
a. Simple fracture - the skin over the fracture site is not broken
b. Compound fracture - a wound from the exterior contacts the
bone at the point of fracture; caused by the broken end of
bone perforating the skin
c. Greenstick fracture - one side of the bone is broken or
splintered, and the other side only bent; found only in young
animals
d. Epiphyseal fracture - occurs at the junction of an epiphysis and
the diaphysis of a bone; limited to young animals

Joints - the articulations (union) between bones Arthrology is the study

of joints and articulations.
Kinds of Joints:
a. Synarthroses - immovable joints
 Suture- junction bet. the bones of the skull
 Gomphosis- articulations of the teeth and their socket
 Synchondrosis- uniting medium is cartilage
 Synostosis – the uniting medium is bone
b. Amphiarthroses - slightly movable joints
 Symphysis- median-line joints united by fibrocartilage
 Syndesmoses- united by fibrous tissues
c. Diarthroses - freely movable joints; the true joints and are also
called synovial joints

29
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
Label the parts of the skeletal system of the chicken.
Application

Fig. 3. Skeletal system of chicken

Source: Hans-vander-lubbe@pixel.com
Good work! You have just finished exploring the skeletal system. This
Closure time, you will be amazed as to how the skeleton aids in locomotion
together with the muscular system, which is the next lesson in this
module.

Module No. Module 2: Anatomy and Physiology I

and Title
Lesson No. Lesson 3. The Muscular System
and Title
Learning After finishing this lesson, you are expected to:
Outcomes Differentiate the kinds of muscle tissue and its functions
Describe the structure of the muscle
Discuss the steps in muscle contraction
Time 2 hours
Frame

Introduction Imagine if you do not have muscles in your body. Probably, you will
just be lying down doing nothing. Walking, jumping, running, or any
movement activity requires muscles. To know more about how
muscle works, let us explore Lesson 3 of this module.

Activity List down 10 activities that you loved

doing. 30

1. 6.
2. 7.
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
3. 8.
4. 9.
5. 10.

Analysis 1. How many among these activities you have listed involved
the muscles?
2. What do you think is the most important function of the muscle?

3. Will your muscle still contract even if you are asleep?

The Muscular System

Abstraction
The muscular system is made up of muscle cells that can contract, thus,
allowing the movement of the skeleton. Muscles make up the bulk of an
animal’s body and account for about half its weight. The muscle
contractions required for movement also produce heat, which
contributes to the maintenance of constant body temperature.

Myology is the study of muscle and their accessory structures.

Kinds of Muscle Tissue

a) Voluntary Striated muscles

 Connected directly or directly
with the skeleton (skeletal
muscle)
 Covers the greater part of the
body and determines its form
 Red in color with varying
shades
 Some are attached to the skin
(cutaneous muscles)
 Individuals cells are striated
(striped), multinuclear located
near the surface
 Each muscle fiber is
controlled by the voluntary
nerve (motor neuron) and is
under conscious condition.

b) Involuntary striated muscles

 Known as cardiac muscle (found in the heart)
 Cells are arranged in a network, striated and nuclei are
centrally located
 Contraction requires no nerve stimulus (no conscious control) 31

c) Smooth muscles
 Involuntary and unstriated
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
 Found in visceral organs, walls of blood vessels, urogenital and
respiratory organs
 Contraction requires no nerve stimulus
 Cells are spindle-shaped, arranged in sheets, bundles, or
network with centrally located nuclei
 Some cells are scattered throughout the tissue (e.g. skin muscle
that raises the hair)

Functions of Muscles
a. Provide power for the movement of various body parts (e.g.
extensor muscle straightens body parts, flexor muscles cause
body parts to bend, abductor muscles move away from the
plane and adductor muscles draw parts toward the body plane).
b. Source of protein
c. Expel or force out secretions of organs, except endocrine
glands (involuntary muscles).
d. Provide impetus for movement of ingesta
e. Responsible for uterine motility
f. Aid in expelling fetus at parturition
g. Causes contraction of the heart and increase or decrease the
diameter of blood vessels (regulates blood flow)

32
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

Structure of Muscles
• Sarcolemma – the thin translucent envelope of a muscle fiber
• Myofibrils – tiny fibers arranged parallel to the long axis of
the fiber
• Epimysium – surrounds entire muscle
• Perimysium – surrounds muscle bundle
• Endomysium – surrounds muscle fiber

Fig. 4. Structure
of skeletal muscle

Muscle contraction

 Sliding filament mechanism of muscle contraction

Fig. 5. Stages in muscle contraction

Test Yourself
Application 1. Identify the kind of muscle tissue that do the following task:
a. control the passing out of urine:

33
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
b. moves bones:
c. passage of food along the intestine:
d. makes you smile:
e. makes the hair stands:
f. makes the diaphragm contract for breathing in: _
g. helps you cough out phlegm:
h. controls the passing out of urine:
i. makes the heart pump blood:
j. dilates the pupil of the eyes:

Happy to see you made it this far. Hopefully, you will have a better
Closure appreciation of how much effort your muscles need to work so that you
can move around. In the next lesson, you will know what controls most
of the systems of the body and how much coordination is necessary
to
synchronize all these body activities.

Module No. Module 2: Anatomy and Physiology I

and Title
Lesson No. Lesson 4: The Nervous System
and Title
Learning  Identify the vital structures of the nervous system.
Outcomes  Relate the functions of the parts of the nervous systems with
the survival and productivity of the animal
Time Frame 1 hour
Introduction As a child, you had probably been warned by adults not to touch a hot
stove or play with fire; and still, you did it. The experience of pain
from burned fingers and immediate response of pulling away your
hands are but just a part of the function of the nervous system. In
animals, the reactions are just the same, but the only difference is that
they received no scolding from their parents. In this lesson, we shall
try to appreciate the function of the nervous system.
List down at least 5 observable behavior of a drunk individual.
Activity

Drunken Behavior
1.
2.
3.
4.
5.

34
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
Analysis What do you think are the reasons why an individual exhibits such
kind of behavior?

What are the effects of alcohol on the functioning of the brain?

Abstraction The Nervous System

Animals must be able to sense and respond to the environment in

which they live if they are to survive. The various systems and organs
in the body must also be linked so they work together. The
adjustment of an animal’s response to changes in the environment
and the complex linking of the various processes in the body that this
response involves is called coordination.

The nervous system is one of the regulating systems (the endocrine

system is the other which will be discussed separately) of the body. It
receives millions of bits of information from both the internal and
external environment and then integrates them to initiate responses
thus, maintaining homeostasis; and eventually, store this information
for future use. Some of this activity is conscious, but much of it
happens without our awareness. Two systems are involved in
coordination are the nervous and endocrine systems. The first
operates via electrical impulses along nerve fibers and the second by
releasing special chemicals or hormones into the bloodstream from
glands.

Functions of the Nervous System:

1. Sensory function - to sense changes (known as stimuli) both

outside and within the body.
2. Integrative function - processing the information received
from the sense organs. The impulses from these organs are
analyzed and stored as memory. The many different impulses
from different sources are sorted, synchronized, coordinated
and the appropriate response initiated. The power to integrate,
remember, and apply experience gives higher animals much
of their superiority.
3. Motor function - the response to the stimuli that cause
muscles to contract or glands to secrete.

35
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

Stimulus – any change in the environment of a nerve which if large

enough will cause the nerve to produce an action potential and
transmit an nerve impulse. Nerve impulses can be thought of as
being like an electric current.

The Neuron
A typical neuron has a cell body containing a nucleus, one or more
branching filaments called dendrites that conduct nerve impulses
towards the cell body and one long fiber, an axon, that carries the
impulses away from it. Many axons have a sheath of fatty material
called myelin surrounding them. This speed up the rate at which the
nerve impulses travel along the nerve.

Fig. 6. Parts of the neuron

Source: https://www.sciencefacts.net/wp-ontent/uploads/2019/12/Parts-
of-a-Neuron-Diagram.jpg

Synapse – is the point of contact between two neurons.

Divisions of the Nervous System

1. The central nervous system (CNS) - consists of the brain and

spinal cord.

36
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
2. The peripheral nervous system (PNS) - consists of the nerves
that connect to the brain and spinal cord (cranial and spinal
nerves) as well as the autonomic (or involuntary) nervous
system.

Divisions of the Nervous System

1. Central Nervous System

a) Brain
 Protected by the skull called the cranium.
 Surrounding by protective membranes called the meninges,
and a crystal-clear fluid called cerebrospinal fluid, which
protects and nourishes the brain tissue.
 Carotid artery, a branch of the dorsal aorta, supplies oxygen
(20% of the oxygen taken into the body) and nutrients to the
brain.
 Brain damage occurs if brain tissue is deprived of oxygen for
only 4-8 minutes.
 Cerebrum (cells of the cerebral cortex or gray matter) - for the
highest type of mental activities: e.g. interpretation of
sensations and reasoning, intellectual functions, memory
storage and processing, conscious and subconscious
regulation of skeletal muscle contractions
 Cerebellum (centrally located or the white matter) - center for
sensory and motor coordination such as voluntary movement,
regulation of posture, and maintenance of equilibrium
 Brain stem (medulla oblongata and pons) - Relay center
connecting the cerebrum and cerebellum to the spinal cord;
contains the control center for respiration; controls heart rate;
controls blood supply and regulation of body heat and some
digestive processes

b) Spinal Cord – the caudal continuation of the medulla oblongata

- Receives sensory (afferent) fibers by way of the dorsal roots
of the spinal nerves.
- Gives off the motor (efferent) fibers to the ventral roots of
the spinal nerves.

2. Peripheral Nervous System - includes all nervous structures

outside the brain and spinal cord.
 Cranial nerves - arise from the cranium consist of 12 nerves
that receive stimulus (sensory) or effect action (motor) or both
 Spinal nerves - emerge from the spinal cord and have 31 pairs
that supply sensory and motor fibers. The appendages are

37
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
supplied by braidlike arrangements of nerves known as
plexuses.
 Brachial plexus - supplied to each forelimb.
 Lumbo-sacral plexus - composed of the right and left
plexuses made of ventral branches of the few lumbar and first
1 or 2 sacral nerves.

3. Autonomic nervous system - part of the peripheral nervous system

that innervates smooth muscles, cardiac muscles, and glands,
subdivided into:

 Sympathetic nervous system - also called the thoracolumbar

portion because the sympathetic outflow is mainly from the
thoracic and lumbar spinal nerves.
 Parasympathetic nervous system - made up of a cranial and
sacral portion.

Reflex - an automatic or unconscious response of effector organ

(muscle or gland) to an appropriate stimulus
Reflex arc – includes an afferent and efferent neuron

Direction: Choose and write the letter of the correct answer in the
Application space before each number.

1. The functional unit of the nervous system is the

a. Meninges
b. Neuron
c. Cell body
d. Brain
2. The brain and the spinal cord are part of the
a. Autonomic nervous system
b. Central nervous system
c. Peripheral nervous system
d. Neuron
3. Two neurons communicate via the
a. Dendrites
b. Axon
c. Cell body
d. Synapse
4. The control center for respiration is in the
a. Medulla oblongata
b. Pons
c. Cerebellum
d. Brain stem
5. Which of this is not a function of the cerebrum?
a. Regulates muscle contraction

38
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
b. Reasoning
c. Maintain equilibrium
d. Enervates smooth muscles
6. Part of the CNS that controls heart rate
a. Cerebellum
b. Cerebrum
c. Medulla oblongata
d. Brain stem
7. Which is a function of the meninges?
a. protect the brain and spinal cord
b. retain memories
c. reasoning
d. regulates temperature
8. Injury to the brain stem may lead to
a. Memory loss
b. Disorientation
c. Lack of coordination
d. Death
9. The passage of nerve impulse in much faster in
a. Unmyelinated axon
b. Myelinated axon
c. Sympathetic nerve
d. Parasympathetic nerve
10. Other than the nervous system, what system is also
involved in regulating all body processes.
a. Endocrine system
b. Cardiovascular system
c. Muscular system
d. Urinary system

Closure Well done! After accomplishing all the activities in lesson 4, you are
now ready to move to lesson 5, which tackles on the cardiovascular
system.

Module No. Module 2: Anatomy and Physiology I

and Title
Lesson No. Lesson 5. The Cardiovascular System
and Title
Learning At the end of this lesson, you are expected to:
Outcomes  Describe the composition and explain the functions of blood
and its components
 Discuss the blood clotting mechanism
 Explain the function of the lymphatic system

Time Frame 1.5 hours

39
Introduction This lesson on the Cardiovascular system is divided is into 4 sections.
These include the blood, the heart, the blood circulation, and the
lymphatic circulation. Each of these topics will be covered in more
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
detail in this chapter.
Survey at least 10 members of your family. Ask each one their
Activity blood type. Compute for the percentage of the people surveyed with
blood groups O, A, B, and AB.
 What blood group has the highest percentage?
Analysis  What blood group has the lowest percentage?
 Why is blood group O considered as a universal red cell
donor?
 Why is blood group AB considered as a universal plasma
donor:

The Cardiovascular System

Abstraction
Generally, the main function of the cardiovascular system is for
transport, regulation, and protection. Transported materials by the
blood include nutrients, waste products, gases, and hormones. It also
helps regulate fluid-electrolyte balance, acid-base balance, and body
temperature. The white blood cells protect the body against pathogens
while the blood platelets initiate blood clotting mechanism that
prevents excessive loss of blood after injuries.

The Heart
 A central pumping organ located in the mediastinal space of
the thoracic cavity opposite the 3rd and 4th ribs.
 Partially surrounded by serous sac, the pericardium which:
o prevents over dilation of the heart
o provides a smooth surface for hearts’ action
o holds the hearts in a fixed position
o assist in the relaxation of the heart
 Layers of the heart
o Epicardium
o Myocardium
o Endocardium
 Chambers of the heart – separated by a septum
o Right and left atria
o Right and left ventricles
 Valves of the heart
o Atrio-ventricular (A-V) valves
o The left is bicuspid
o The right is tricuspid
o Semilunar (S-L) valves – prevents blood from
returning into the ventricles

40
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
o Aortic S-L valve
 Pulmonary S-L valve
 Systole – the contraction of a chamber of the heart in the
process of partially emptying the chamber.
 Diastole – the relaxation of the chamber of the heart just
before and during the filling of that chamber.

The Blood Vessels

a. Arteries and arterioles – carry blood away from the heart
b. Veins and venules – carry blood toward the heart
c. Capillaries – tiny tubes acting as selective membranes that lie
between the arteries and veins.

The Blood
 Composed of the following:
a) Plasma – the fluid portion of the blood
b) Corpuscles – the red and white blood cells, blood platelets

Red blood cells (erythrocytes)

 Non-nucleated
 Biconcave circular disc
 Contains hemoglobin, a complex iron-containing conjugated
protein that transport oxygen

White blood cells (Leukocytes)

 Nucleated
 Independent movement
 Classified as:
o Granulocytes - Neutrophils
- Eosinophils
- Basophils

o Agranulocytes - Monocytes
- Lymphocytes

Blood Platelets (Thrombocytes)

 Small oval disk-like granulated bodies 2-4 microns in
diameter
 Liberate thromboplastin which aids in blood clotting and they
play a role in clot reactions

41
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

42
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
Blood Clotting Mechanism

The stages in blood clotting are shown below:

Fig. 8. Stages in blood clotting

Source: https://ib.bioninja.com.au/standard-level/topic-6-human-
physiology/63-defence-against-infectio/clotting.html

The Pulse
 Pulse is a wave of dilatation of an artery as blood flows into
it.
 Pulse rate is determined by:
o Pressing superficial artery with thumb
o Use of Stethoscope
 Factors affecting pulse rate:
o Age
o Excitement
o Muscular exercise
o High environmental temperature
o Digestion of food
o Sleep
o Disease/illness
 Take pulse rate at:
o External maxillary artery – for horse, cattle,
and carabao
o Femoral artery – for sheep, goat, dog, and cat
 The pulse rate of farm animals:
Horse 38/min
Carabao and Cattle 54/min
Goat 78/min
Chicken 200-400/min

43
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

 Tachycardia - a considerable increase in pulse rate/heart rate

 Bradycardia - considerable decrease in pulse rate/heart rate
 Blood groups and types
 There are four major blood groups (A, B, AB, O) and eight
different blood types (A+, A-, B+, B- etc.).
 The groups are based on whether you have two specific
antigens: A and B
o Group A has the A antigen and B antibody.
o Group B has the B antigen and the A antibody.
o Group AB has A and B antigens but neither A nor B
antibodies.
o Group O does not have A or B antigens but has both A
and B antibodies.
 There is also a third kind of antigen called the Rh factor.
You either have this antigen (“Rh+” or “positive”), or you do
not (“Rh-” or “negative”).

B. The Lymphatic System

 The lymphatic system is composed of:

o Lymphoid tissues
o Lymph vessels

Lymph vessels or Lymphatics

 Carry tissue fluid and lymph
 Consist of:
o Longer lymph vessels (thoracic duct and right lymphatic
duct)
o Lymph capillaries

The Lymph glands

 Filtration of lymph fluids and production of lymphocytes
o It is also made up of the following:
a) Lymph - a liquid between the tissues and the
blood vessels (capillaries)
- few red corpuscles and lymphocytes
- low protein content
- high in bicarbonates and chlorides
- slightly higher pH than plasma
- colorless fluid with specific gravity of
1:015.
b) Lymph nodes - a lymph gland through which the
lymph passes; it produces lymphocytes and filters extraneous
bodies

Functions of the lymphatic system

a) For draining tissue fluids
44
b) Assists in the control of interstitial fluid pressure
c) Acts as a defense mechanism against noxious materials.
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

Application Trace the flow of oxygenated blood from the lungs to the liver
and the unoxygenated blood from the liver back to the lungs.
Identify all blood vessels and organs involved. Submit your
illustration or diagram in an A4 size bond paper.

Closure How did you find the activities in Lesson 5? Can you relate the lesson
to your everyday life? Next, we will proceed to Lesson 6 on the
Respiratory System, which is also a very interesting topic.

Module No. Module 2: Anatomy and Physiology I

and Title
Lesson No. Lesson 6. The Respiratory System
and Title
Learning At the end of this lesson, you are expected to:
Outcomes  Trace the passage of air in and out of the lungs
 Differentiate internal and external respiration
 Describe the different forms of respiration
Time Frame 1.5 hours
Introduction Have you ever wondered why you need to breathe? Well, breathing is
central to life because it allows the body to obtain the energy it needs
to sustain itself and its activities. But how does it work? Lesson 6 on
the respiratory system will lead to a deeper understanding of its
function.

Activity Perform the following task:

 First exercise: Breathe normally for 60 seconds and record your
respiratory rate (equivalent to one inspiration and one expiration)
 Second exercise: Hold your breath for 30 to 45 seconds, once the
breath has been released, start recording your respiratory rate for
60 seconds.
 Record your data on the table below.

Holding of Breath

Before After

breaths / minute breaths / minute

45
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
Answer the following questions:
Analysis 1. What is the difference in respiratory rate between before and
after the holding of breath?

2. What do you think is the reason for the difference in the rate
of respiration?

3. Why can’t you hold your breath for a long time?

The Respiratory System

Abstraction
Respiration is the process of exchanging gases between the blood and
the external environment. Most of the respiratory system is concerned
with what we think of as breathing: moving air into and out of the
lungs. Oxygen enters the body from the air and carbon dioxide is
usually eliminated from the same part of the body. This process is
called gas exchange.

Importance
 Involves the exchange of gases between the blood and
the external environment
 Animals may survive for days without food but only
for minutes without oxygen.

Breathing - is usually an unconscious activity that takes place

whether you are awake or asleep, although, humans at least, can also
control it consciously.

Control of Breathing

Two regions in the hindbrain called the medulla oblongata and pons
control the rate of breathing. These are called respiratory centers.
They respond to the concentration of carbon dioxide in the blood.
When this concentration rises during a bout of activity, nerve
impulses are automatically sent to the diaphragm and rib muscles that
increase the rate and the depth of breathing. Increasing the rate of
breathing also increases the amount of oxygen in the blood to meet
the needs of this increased activity.

46
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
The respiratory organs/apparatus
1. Nostrils/nares
 external openings of air passages
2. Nasal cavity
 opens externally at nostrils and communicates with
pharynx thru posterior nares
 divided into right and left by the cartilaginous nasal
septum
3. Pharynx
 A common passage for air and food
4. Larynx or voice box
 Consist of five cartilages:
o cricoid
o arytenoids (2)
o thyroid
o epiglottis
5. Trachea or windpipe
 connects larynx with lungs
 divides into bronchi which form smaller branches
(bronchioles)
6. Lungs
 situated in the pleural cavities of the thorax
 cone-shaped structure with the base resting against the
cranial side of the diaphragm and the apex within or
close to the thoracic inlet.
 Divided into lobes:
o apical (cranial)
o cardiac (middle)
o diaphragmatic (caudal)
o intermediate lobe (right lung)

[NOTE: Lungs of horses have no subdivisions, except for

intermediate lobe]

Regulation of respiration
 Involves both external and internal respiration

External respiration - the thin membranes of the alveolar wall

and capillaries facilitate the movement of oxygen into the blood
and movement of carbon dioxide into the alveolar air (exchange
of gases between the environment and the lungs).
Internal respiration - oxygen from the blood is diffused to
the tissues for cellular oxidation and the resulting carbon
dioxide diffuses into the blood (exchange of gases between the
blood and tissues).

The process involves the following:

Inspiration 47
 the taking in of O2 into the lungs accomplished by
enlargement of the thorax

Inspiration occurs when muscle contraction causes the
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
ribs to move up and out and the diaphragm to flatten.

These movements increase the volume of the pleural
cavity and draw air down the respiratory system into
the lungs.

The air enters the nasal cavity and passes to the
pharynx and larynx where the epiglottis closes the
opening to the lungs during swallowing. the air passes
down the trachea kept open by rings of cartilage to the
bronchi and bronchioles and then to the alveoli.

The rate of breathing is determined by the
concentration of carbon dioxide in the blood. As
carbon dioxide makes the blood acidic, the rate of
breathing helps control the acid/base balance of the
blood.

The cells lining the respiratory passages produce
mucus which traps dust particles, which are wafted
into the nose by cilia.

Expiration

the outflow of air from the lungs

it is a passive process requiring no energy as it relies
on the relaxation of the muscles and recoil of the
elastic tissue of the lung

Forms of respiration

Apnea - no respiration

Eupnea - normal quiet respiration

Dyspnea - difficult respiration

Hyperpnea - increased depth or rate of breathing or
both

Polypnea - rapid, shallow breathing

Coastal/Thoracic breathing - considerable movement
of ribs.

Abdominal/diaphragmatic breathing - the visible
movement of the abdomen.

Diffusion and Transport of Gases

Oxygen diffuses from high concentration to low concentration. It,

therefore, crosses the narrow barrier between the alveoli and the
capillaries to enter the blood and combine with the hemoglobin in the
red blood cells to form oxyhemoglobin.

48
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2

Blood entering the lung capillaries is full of carbon dioxide that it has
collected from the tissues. Most of the carbon dioxide is dissolved in
the plasma either in the form of sodium bicarbonate or carbonic acid.
As the blood enters the lungs the carbon dioxide gas diffuses through
the capillary and alveoli walls into the water film and then into the
alveoli. Finally, it is removed from the lungs during breathing out.

Breathing in Birds

 The lungs are fixed and do not change shape.

 Birds have air sacs that reach into the bones and have no
diaphragm
 Air is moved in and out of the respiratory system through
pressure changes in the air sacs.
 In the avian lung, the gas exchange occurs in the walls of
microscopic tubules, called ‘air capillaries.’
 The bird’s respiratory system takes up 20% of a birds’ volume
(our respiratory system takes up only 5% of our volume).
 Birds’ respiratory efficiency gives them enough oxygen for
flight.

 Trace a molecule of oxygen from the external nares to the

Application pulmonary capillaries of the lungs
 Trace a molecule of CO2 in the liver until it reaches the
alveoli of the lungs
Congratulation! You are now halfway through the amazing creation
Closure called the body. Although complex and mind-boggling, yet this
module is so interesting. To understand completely, you must
proceed to Module 3 for more astounding discoveries on how the
body works and functions.

MODULE SUMMARY
 The skin consists of two layers: the thin outer epidermis and under it the
thicker dermis.
 Various skin structures formed in the epidermis are made of keratin that
include claws, nails, hoofs, horns, hair, and feathers.
 The skeleton maintains the shape of the body, protects internal organs, and
makes locomotion possible.
 Bones articulate against each other at joints.
 Three different kinds of muscle tissue exist that include smooth muscle found
in the walls of the blood vessels and guts; cardiac muscle in the heart and
skeletal muscle attached to the skeleton.

 The muscle contributes to the maintenance of constant body temperature by

producing heat during muscle contraction. 49
 The neuron is the basic unit of the nervous system which consists of a cell
body with a nucleus, filaments known as dendrites and a long fiber known as
the axon often surrounded by a myelin sheath.
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
 The nervous system is divided into the central nervous system, consisting of
the brain and spinal cord and the peripheral nervous system consisting of
cranial and spinal nerves and the autonomic nervous system.
 The brain consists of the cerebrum, cerebellum, and the brain stem containing
the medulla oblongata and pons.
 The main functions of blood are the transport of oxygen, food, waste products,
etc., the maintenance of homeostasis and defending the body from disease.
 Blood consists of fluid, plasma, in which platelets, red and white blood cells
are suspended.
 Blood is carried away from the heart via the arteries. They have thick elastic
walls that stretch and carries oxygenated blood. Capillaries are small, thin-
walled vessels that facilitate exchange of gases between the blood and the cells
of the tissues. Veins return unoxygenated blood to the heart and have thinner
walls than arteries.
 The air enters the nasal cavity and passes to the pharynx and larynx where the
epiglottis closes the opening to the lungs during swallowing. The air passes
down the trachea kept open by rings of cartilage to the bronchi and
bronchioles and then to the alveoli of the lungs.
 Oxygen diffuses from the alveoli into the red blood cells in the capillaries.
Carbon dioxide, at high concentration in the blood, diffuses into the alveoli to
be breathed out.
 The rate of breathing is determined by the concentration of carbon dioxide in
the blood.

REFERENCES
Animal Science and Dairy Cluster. Lecture Syllabus in Animal Science 1: Introduction to
Animal Science. University of the Philippines Los Baños, College, Laguna.
Frandson, R.D., W.L. Wilke, A. Fails. 2009. Anatomy and Physiology of Farm Animals.
7th edition. Wiley-Blackwell.
Scanlon, Valerie C., and Tina Sanders. Essentials of anatomy and physiology. 5th ed.2007.
F. A. Davis Company. Philadelphia, PA 19103
Rhoades, Rodney A. and George A. Tanner, Medical Physiology. 2nd ed. 2003.
Lippincott Williams & Wilkins. Philadelphia, PA.
https://www.proprofs.com/quiz-school/upload/yuiupload/973979470.jpg
https://www.entwellbeing.com.au/skincare/skin-basics/layers-of-skin/Source: Mayo
Foundation for Medical Education Research
Long bone. Provided by Wikipedia. Located at: http://en.wikipedia.org/wiki/Long_bone.
License: CC BY-SA: Attribution-ShareAlike
Hans-vander-lubbe@pixel.com
https://courses.lumenlearning.com/boundless-ap/chapter/introduction-to-bone/
https://www.medicalnewstoday.com/articles/321617#five-fun-facts 50
https://www.sciencefacts.net/wp-content/uploads/2019/12/Parts-of-a-Neuron-
Diagram.jpg https://www.sciencefacts.net/wp-content/uploads/2019/11/Types-of-
AS 211 - INTRODUCTION TO ANIMAL SCIENCE
MODULE 2
Blood-Cells.jpg
https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/63-defence-against-
infectio/clotting.html
https://open.umn.edu/opentextbooks/textbooks/anatomy-and-physiology-of-animals/

51