BIOL251 Human Anatomy & Physiology I
w/Lab 2026 | Module 4:The Lymphatic System
and Immunity Exam Review |70+ Questions
and Answers Summary |LockDown Browser
|Portage Learning
Module 4: The Lymphatic System and Immunity
This module covers the anatomy and physiology of the lymphatic system and the immune
system's adaptive and innate defenses.
Lymphatic Vessels: Transport lymph, a fluid containing immune cells and waste
products.
Lymphoid Organs: Lymph nodes, spleen, thymus, and tonsils.
Immune Responses:
o Innate Immunity: Non-specific defenses such as barriers and phagocytes.
o Adaptive Immunity: Specific responses involving lymphocytes (B cells and T
cells).
Lymphatic Transport: Movement of lymph through vessels, aided by muscle
contractions and valves.
Section 1: Structure and Functions of the Lymphatic System (Questions 1–15)
,1. What is the primary functional relationship between the lymphatic system and the
cardiovascular system?
A) The lymphatic system pumps blood to tissues when the heart is in diastole.
,B) The lymphatic system returns leaked fluids and plasma proteins from the interstitial
space back to the blood.
C) The lymphatic system is the sole producer of erythrocytes in adults.
D) The lymphatic system controls the constriction of muscular arteries.
Answer: B) The lymphatic system returns leaked fluids and plasma proteins from the
interstitial space back to the blood. Explanation: As blood circulates, hydrostatic
pressure forces fluid out of capillaries into tissues. The lymphatic system gathers this lost
fluid (up to 3 liters per day) and returns it to the venous system to maintain blood volume.
2. Once interstitial fluid enters the lymphatic capillaries, it is officially called:
A) Plasma
B) Cytosol
C) Lymph
D) Interstitial serum
Answer: C) Lymph Explanation: Lymph is the term used specifically for interstitial fluid
once it passes from the interstitial spaces into the specialized lymphatic capillaries.
3. In which direction does lymph flow within the body?
A) In a circular loop, similar to blood flow.
B) Away from the heart only.
C) Toward the heart only.
D) Upward in the arms and downward in the legs.
Answer: C) Toward the heart only. Explanation: The lymphatic system is a one-way
system; there is no circuit. Lymph flows only toward the heart, starting at microscopic, blind-
ended lymphatic capillaries in the tissues.
4. Which structural feature allows lymphatic capillaries to be exceptionally permeable
compared to blood capillaries?
, A) The presence of a thick elastic basement membrane.
B) Overlapping endothelial cells that form flap-like, one-way minivalves.
C) Large fenestrations in the tunica media.
D) Direct connections to the lumen of arterioles.
Answer: B) Overlapping endothelial cells that form flap-like, one-way minivalves.
Explanation: The edges of adjacent endothelial cells overlap loosely, acting as
minivalves. When interstitial fluid pressure rises, these flaps open easily to let fluid in, but
close when internal pressure rises to prevent escape.
5. Lymphatic capillaries are anchored to surrounding connective tissue matrix by:
A) Elastic laminae
B) Collagen filaments
C) Gap junctions
D) Desmosomes
Answer: B) Collagen filaments Explanation: Collagen filaments anchor the endothelial
cells to surrounding structures. This ensures that when tissue swells with fluid, the filaments
are pulled, physically opening the minivalves to increase lymph drainage.
6. In which of the following tissues are lymphatic capillaries completely absent?
A) Skeletal muscle
B) Bones, teeth, and the central nervous system
C) Mucosa of the digestive tract
D) Dermis of the skin
Answer: B) Bones, teeth, and the central nervous system Explanation: Lymphatic
vessels are absent from avascular tissues, bones, teeth, bone marrow, and the central
nervous system (which drains excess fluid via cerebrospinal fluid).
w/Lab 2026 | Module 4:The Lymphatic System
and Immunity Exam Review |70+ Questions
and Answers Summary |LockDown Browser
|Portage Learning
Module 4: The Lymphatic System and Immunity
This module covers the anatomy and physiology of the lymphatic system and the immune
system's adaptive and innate defenses.
Lymphatic Vessels: Transport lymph, a fluid containing immune cells and waste
products.
Lymphoid Organs: Lymph nodes, spleen, thymus, and tonsils.
Immune Responses:
o Innate Immunity: Non-specific defenses such as barriers and phagocytes.
o Adaptive Immunity: Specific responses involving lymphocytes (B cells and T
cells).
Lymphatic Transport: Movement of lymph through vessels, aided by muscle
contractions and valves.
Section 1: Structure and Functions of the Lymphatic System (Questions 1–15)
,1. What is the primary functional relationship between the lymphatic system and the
cardiovascular system?
A) The lymphatic system pumps blood to tissues when the heart is in diastole.
,B) The lymphatic system returns leaked fluids and plasma proteins from the interstitial
space back to the blood.
C) The lymphatic system is the sole producer of erythrocytes in adults.
D) The lymphatic system controls the constriction of muscular arteries.
Answer: B) The lymphatic system returns leaked fluids and plasma proteins from the
interstitial space back to the blood. Explanation: As blood circulates, hydrostatic
pressure forces fluid out of capillaries into tissues. The lymphatic system gathers this lost
fluid (up to 3 liters per day) and returns it to the venous system to maintain blood volume.
2. Once interstitial fluid enters the lymphatic capillaries, it is officially called:
A) Plasma
B) Cytosol
C) Lymph
D) Interstitial serum
Answer: C) Lymph Explanation: Lymph is the term used specifically for interstitial fluid
once it passes from the interstitial spaces into the specialized lymphatic capillaries.
3. In which direction does lymph flow within the body?
A) In a circular loop, similar to blood flow.
B) Away from the heart only.
C) Toward the heart only.
D) Upward in the arms and downward in the legs.
Answer: C) Toward the heart only. Explanation: The lymphatic system is a one-way
system; there is no circuit. Lymph flows only toward the heart, starting at microscopic, blind-
ended lymphatic capillaries in the tissues.
4. Which structural feature allows lymphatic capillaries to be exceptionally permeable
compared to blood capillaries?
, A) The presence of a thick elastic basement membrane.
B) Overlapping endothelial cells that form flap-like, one-way minivalves.
C) Large fenestrations in the tunica media.
D) Direct connections to the lumen of arterioles.
Answer: B) Overlapping endothelial cells that form flap-like, one-way minivalves.
Explanation: The edges of adjacent endothelial cells overlap loosely, acting as
minivalves. When interstitial fluid pressure rises, these flaps open easily to let fluid in, but
close when internal pressure rises to prevent escape.
5. Lymphatic capillaries are anchored to surrounding connective tissue matrix by:
A) Elastic laminae
B) Collagen filaments
C) Gap junctions
D) Desmosomes
Answer: B) Collagen filaments Explanation: Collagen filaments anchor the endothelial
cells to surrounding structures. This ensures that when tissue swells with fluid, the filaments
are pulled, physically opening the minivalves to increase lymph drainage.
6. In which of the following tissues are lymphatic capillaries completely absent?
A) Skeletal muscle
B) Bones, teeth, and the central nervous system
C) Mucosa of the digestive tract
D) Dermis of the skin
Answer: B) Bones, teeth, and the central nervous system Explanation: Lymphatic
vessels are absent from avascular tissues, bones, teeth, bone marrow, and the central
nervous system (which drains excess fluid via cerebrospinal fluid).
