Tetrapods vs. Sarcopterygians Anatomy

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Questions and Answers

Which anatomical feature differentiates tetrapods from other sarcopterygians?

Presence of elongated snout (correct)

Presence of median fins

Presence of operculum

Presence of cervical vertebrae (correct)

Which of the following is NOT a group of hypaxial muscles in tetrapods?

Subvertebralis

Internal oblique

Rectus femoris (correct)

Transversus abdominis

What is the primary function of the glenoid fossa in tetrapods?

To facilitate locomotion

To form a joint with the humerus (correct)

To support the pelvic girdle

To protect the abdominal cavity

Which bone does the acetabulum interact with?

Femur Signup and view all the answers

What term describes structures supporting the back limbs in tetrapods?

Pelvic girdle Signup and view all the answers

Which of the following correctly describes the term 'distal'?

Farthest away from the body Signup and view all the answers

What anatomical feature aids in locomotion while also affecting respiration in basal tetrapods?

Trunk muscles Signup and view all the answers

Which of the following lists the bones of the pectoral limb in the correct order from proximal to distal?

Humerus, Radius and ulna, Carpals, Metacarpals, Phalanges Signup and view all the answers

What is the primary function of the olecranon in the elbow joint?

It acts as a lever arm for muscle attachment. Signup and view all the answers

In which order are the bones of the pelvic limb listed from proximal to distal?

Femur, Patella, Tibia and Fibula, Tarsals, Metatarsals, Phalanges Signup and view all the answers

What is the role of the calcaneus in the locomotion of animals?

It serves as a point of attachment for tendons extending the hock joint. Signup and view all the answers

Which term describes the bottom surface of the front paw in animals?

Palmar Signup and view all the answers

Which type of muscle is most associated with movement in the appendicular skeleton?

Skeletal muscle Signup and view all the answers

What is the literal definition of 'extension' in anatomical terms?

Bringing bones of a joint further apart Signup and view all the answers

Which of the following muscles can be categorized as a dorsal muscle supporting the pectoral girdle?

Latissimus dorsi Signup and view all the answers

What is the function of tendons in the musculoskeletal system?

To connect muscles to bones Signup and view all the answers

What is the primary function of the amnion in the amniote egg?

Protects the embryo from mechanical damage Signup and view all the answers

Which of the following best describes the Reptiliomorpha clade?

Consists of amniotes and their more recent extinct relatives Signup and view all the answers

What significant challenge does the amniote egg help to address?

Protects the embryo from mechanical injury Signup and view all the answers

During amniocentesis, which membranes does the needle pass through?

Amnion and chorion Signup and view all the answers

What anatomical feature is NOT typical of amniotes compared to other tetrapods?

Absence of an eardrum Signup and view all the answers

What distinguishes a hock joint with a mesotarsal joint from a simple hock joint?

Allows for greater movement between the tarsals Signup and view all the answers

Why is internal fertilization essential for amniotes?

It ensures the ovum is fertilized prior to membrane formation Signup and view all the answers

Which of the following functions is performed by the allantois?

Facilitates gas exchange alongside the chorion Signup and view all the answers

What is the primary function of the stapes in amniotes?

It transmits vibrations from the tympanum to the inner ear. Signup and view all the answers

How does the trachea of amniotes differ from that of basal tetrapods and amphibians?

It is supported by cartilage rings. Signup and view all the answers

What does the term 'anapsid' refer to in terms of skull structure?

Organisms with no openings in the skull. Signup and view all the answers

What characterizes synapsid organisms?

They possess one pair of lateral fenestrae in the skull. Signup and view all the answers

What is the primary role of intercostal muscles during respiration?

They create negative pressure in the thorax to aid lung expansion. Signup and view all the answers

Define costal ventilation in regards to rib movement.

It utilizes intercostal muscle contraction to create pressure changes. Signup and view all the answers

What anatomical structure is essential for the functioning of an aspiration pump in respiration?

Diaphragm. Signup and view all the answers

How do sauropsid lungs differ from synapsid lungs?

Sauropsid lungs are rigid and air moves in one direction. Signup and view all the answers

What is one primary function of the circulatory system?

Enables internal respiration Signup and view all the answers

In which type of circulatory system does blood pass through the heart only once?

Single circulatory system Signup and view all the answers

Where does the electrical impulse for each heartbeat originate in amniotes?

Sinoatrial node Signup and view all the answers

Which of the following statements about the turtle heart is correct?

It can mix oxygenated and deoxygenated blood Signup and view all the answers

What is the significance of blood temperature regulation in the circulatory system?

It helps maintain homeostasis Signup and view all the answers

Which heart structure primarily differentiates a three-chambered heart from a four-chambered heart?

The single ventricle Signup and view all the answers

In a dual circulatory system, how many times does blood pass through the heart in a complete circuit?

Twice Signup and view all the answers

What key advantage do turtles have in their circulatory system compared to other species?

They can consciously regulate blood flow between circuits Signup and view all the answers

Study Notes

Anatomical Differences: Tetrapods vs. Sarcopterygians

Tetrapods lack median fins, have elongated snouts, and lack opercula.
Tetrapods possess cervical vertebrae, simple lungs, and a short trachea.
Ribs in tetrapods support the body, they have zygapophyses, and have one sacral vertebra connecting to the pelvis.
Tetrapods have stout limbs with digits, a simple hock joint, and specific muscle arrangements: Epaxial muscles connect many vertebrae, Hypaxial muscles are divided into five groups.
Kidneys in tetrapods extend the length of the trunk, they have urinary bladders, and lateral lines are only present in aquatic species or larvae.
Adult frogs have an eardrum and stapes.

Tetrapod Hypaxial Muscle Groups

Subvertebralis: Located immediately ventral to the vertebrae, forming the roof of the thoracic and abdominal cavities.
Transversus abdominis: The most medial layer of the lateral muscles.
Internal oblique: The middle layer of the lateral muscles.
External oblique: The most lateral layer of the lateral muscles.
Rectus abdominis: The most ventral muscle, forming the floor of the thoracic and abdominal cavities.

Ancestral Tetrapod Locomotor System & Respiration

Basal tetrapods utilize trunk muscles for lateral body bending locomotion (anguilliform movement).
This interferes with respiration because lateral bending contracts muscles on only one side, while exhalation requires simultaneous contraction of both sides.

Appendicular Skeleton & Pectoral Girdle

Appendicular Skeleton: The fins/limbs and their support structures.
Pectoral Girdle: Supports the front fins/limbs, composed of:
- Clavicle
- Coracoid
- Scapula

Glenoid Fossa & Pelvic Girdle

Glenoid Fossa: The site of interaction between the pectoral girdle and the humerus, forming the shoulder joint.
Pelvic Girdle: Supports the back fins/limbs, composed of:
- Ilium
- Ischium
- Pubis

Acetabulum & Obturator Foramen

Acetabulum: The site of interaction between the femur and the pelvis, forming the hip joint.
Obturator Foramen: Allows for passage of blood vessels and nerves.

Proximal & Distal Definitions

Proximal: Closer to the body.
Distal: Farthest away from the body.

Pectoral & Pelvic Limb Bone Order

Pectoral Limb (Proximal to Distal):
- Humerus
- Radius and Ulna
- Carpals
- Metacarpals
- Phalanges
Pelvic Limb (Proximal to Distal):
- Femur
- Patella
- Tibia and Fibula
- Tarsals
- Metatarsals
- Phalanges

Olecranon & Calcaneus

Olecranon: The most proximal part of the ulna, forming the elbow joint with the humerus.
Calcaneus: A tarsal bone, part of the hock joint, where the tendon for joint extension attaches.

Palmar & Plantar Definitions

Palmar: Refers to the bottom surface of the front paw.
Plantar: Refers to the bottom surface of the back paw.

Appendicular Skeleton & Muscle Belly

Skeletal muscle is most involved with the appendicular skeleton.
Muscle Belly: The concentrated mass of muscle cells and fibers responsible for contractile force.

Pectoral Girdle Muscle Groups

Branchiomeric Muscles: Example: Trapezius.
Axial Muscles: Example: Serratus ventralis.
Dorsal Muscles: Example: Latissimus dorsi.
Ventral Muscles: Example: Pectoralis.

Joint Levers: Input & Output Arms

Joints can act as levers, with the input arm determining force/velocity of the output arm.
Input Arm: The size of the input arm affects the force and velocity of the output arm.
Output Arm: A larger input arm generates greater output force, while a smaller input arm allows for greater output velocity.

Tendons & Ligaments

Tendons: Connect muscles and bones.
Ligaments: Connect bones and/or cartilages.

Movement Definitions

Flexion: Bringing bones of a joint closer.
Extension: Bringing bones of a joint further apart.
Adduction: Drawing a limb closer to the body's center.
Abduction: Drawing a limb away from the body's center.

Reptiliomorpha

The clade containing amniotes and extinct organisms more closely related to amniotes than amphibians.

Amniote Egg Extraembryonic Membranes

Amnion: Protects the embryo from mechanical damage.
Chorion: Allows gas exchange with the allantois.
Allantois: Stores nitrogenous wastes, assists in gas exchange with the chorion.
Yolk Sac: Stores and transports nutrients to the embryo.

Amniote Egg's Adaptations for Land

The amniote egg protects the embryo from dehydration, mechanical injury, and infections.

Amniocentesis & Extraembryonic Membranes

Amniocentesis involves withdrawing amniotic fluid, avoiding fetus, placenta, and umbilical cord.
The needle passes through the amnion and chorion.

Anatomical Differences: Amniotes vs. Other Tetrapods

Amniotes have elongated necks, longer tracheas with cartilage rings, lungs divided into alveoli, and longer ribs aiding in ventilation.
They possess well-developed zygapophyses, two or more sacral vertebrae, slender limbs, mesotarsal joints, and specialized epaxial and hypaxial muscles aiding in ventilation.
Amniote kidneys are compacted, lateral lines are absent, and eardrums and stapes are always present.

Simple vs. Mesotarsal Hock Joint

Simple Hock Joint: No distinct motion between tarsal bones.
Mesotarsal Joint: Tarsal bone fusion creates astragalus and calcaneus, allowing greater movement and stronger hindlimb force generation.

Internal Fertilization in Amniotes

The protective membranes form within the mother, requiring fertilization before their development.
External fertilization is not effective as sperm cannot penetrate the protective membranes.

Function of the Stapes in Amniotes

The stapes transmits vibrations from the tympanum to the inner ear.

Amniote Trachea

Amniotes have tracheas supported by cartilage rings, unlike basal tetrapods and amphibians.

Fenestrae

A small hole or opening in the skull.

Cranial Fenestra Types

Anapsid: No openings in the skull, solid covering over the roof and sides.
Synapsid: One pair of holes (lateral fenestrae) in the skull.
Diapsid: Two pairs of holes (lateral fenestrae) in the skull.
Sauropsid: A diapsid subgroup with modified fenestrae.

Ventilation

Active process of moving water or gas across the respiratory surface.

Muscles Involved in Respiration

Intercostal muscles (between ribs)
Diaphragm (where present)

Costal Ventilation & Aspiration Pump

Costal Ventilation: Intercostal muscles move ribs, creating negative pressure in the thorax and expanding lungs.
Aspiration Pump: Intercostal muscles and the diaphragm enlarge the thoracic cavity, expanding the lungs and pulling in air. The diaphragm is essential for this pump.
- Exhalation occurs through compression of the thoracic cavity by intercostal, diaphragm, and sometimes abdominal muscles.

Sauropsid & Synapsid Lung Structure

Sauropsids (Faveolar Lungs): Rigid, with tube-like faveolae lining the airways. Air moves unidirectionally over the faveolae.
Synapsids (Alveolar Lungs): Compress and expand, with gas exchange in alveoli at the end of branching airways. Air moves in and out of the alveoli through the same passage.

Functions of the Circulatory System

Enables internal respiration
Distributes nutrients and hormones
Distributes immune cells and antibodies
Temperature regulation

Single vs. Dual Circulatory Systems

Single: Blood passes through the heart once per complete circuit.
Dual: Blood passes through the heart twice per complete circuit.

Heartbeat Impulse Origin in Amniotes

Sinoatrial node (SA node)

Blood Flow Paths: Heart Chambers

Two Chambers:
- Atrium → Ventricle → Body → Gills → Atrium
Three Chambers:
- Right Atrium → Ventricle → Body → Right Atrium
- Left Atrium → Lung → Left Atrium
Four Chambers:
- Right Atrium → Right Ventricle → Lung → Left Atrium → Left Ventricle → Body → Right Atrium

Turtle Heart: Not Inferior to Humans

Turtles have a partially divided ventricle, leading to some mixing of oxygenated and deoxygenated blood.
However, turtles can shift blood between the systemic and pulmonary circuits to meet immediate needs (e.g., warming or diving), allowing for separation of oxygenated and deoxygenated blood.

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Description

Explore the anatomical differences between tetrapods and sarcopterygians with this quiz. Discover unique features such as limb structure, muscle groups, and respiratory systems, as well as the specific adaptations of tetrapods. Test your knowledge on these fascinating vertebrate classifications.