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Questions and Answers
What is the primary function of short bones?
What is the primary function of short bones?
Which part of the skeleton includes the skull and vertebral column?
Which part of the skeleton includes the skull and vertebral column?
What type of bone is characterized by being tubular and longer than it is wide?
What type of bone is characterized by being tubular and longer than it is wide?
What is the primary role of cartilage in the skeletal system?
What is the primary role of cartilage in the skeletal system?
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Which statement accurately differentiates compact bone from spongy bone?
Which statement accurately differentiates compact bone from spongy bone?
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What is the primary function of sesamoid bones?
What is the primary function of sesamoid bones?
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Which type of joints are characterized by being freely movable and having a cavity?
Which type of joints are characterized by being freely movable and having a cavity?
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Which of the following joint types allows movement in multiple axes?
Which of the following joint types allows movement in multiple axes?
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What type of movement do plane/gliding joints primarily allow?
What type of movement do plane/gliding joints primarily allow?
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Which of the following is NOT a characteristic of solid joints?
Which of the following is NOT a characteristic of solid joints?
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What role does the pulmonary trunk serve in the circulatory system?
What role does the pulmonary trunk serve in the circulatory system?
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Where does the coronary sinus drain blood?
Where does the coronary sinus drain blood?
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Which part of the heart initiates the cardiac cycle?
Which part of the heart initiates the cardiac cycle?
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What structure drains deoxygenated blood from the thorax and upper body?
What structure drains deoxygenated blood from the thorax and upper body?
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Which arteries provide oxygenated blood to the heart itself?
Which arteries provide oxygenated blood to the heart itself?
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What is the main function of the AV node in the heart?
What is the main function of the AV node in the heart?
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Which structure surrounds and encapsulates the lungs?
Which structure surrounds and encapsulates the lungs?
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What is the purpose of the intercostal muscles in the thorax?
What is the purpose of the intercostal muscles in the thorax?
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From which part of the aorta do the coronary arteries arise?
From which part of the aorta do the coronary arteries arise?
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What happens to the signals received at the SA node?
What happens to the signals received at the SA node?
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Study Notes
Skeletal System Overview
- The skeletal system provides support for the body and serves as attachment points for muscles.
- It protects vital organs, stores calcium and phosphorus, and plays a role in blood production.
- The skeletal system can be divided into the axial skeleton (skull, vertebral column, ribs, and sternum) and the appendicular skeleton (upper and lower limbs).
Bone Types
- Adults have between 206 and 213 bones, while infants have approximately 270.
- Bones are composed of two types: Spongy (cancellous or trabecular) bone, which is found in the inner part of the bone and contains marrow for blood cell formation, and Compact (cortical) bone, which forms the dense outer shell of the bone.
Cartilage
- Cartilage is a semirigid, avascular connective tissue that provides flexibility in the skeleton.
- Its functions include supporting soft tissues, providing a smooth surface for bone articulation at joints, and enabling the growth of long bones.
- There are three types of cartilage: Hyaline, elastic, and fibrocartilage.
Bone Classifications
- Long bones are tubular shaped bones longer than they are wide, commonly found in the limbs.
- Short bones are cube-shaped, providing stability with minimal movement.
- Flat bones are broad, flat plates often involved in muscle attachment and protection.
- Irregular bones have no defined form and can't be classified into other categories. They serve various functions, including protection, muscle attachment, and tissue support.
- Sesamoid bones are found within tendons or muscles, primarily assisting with movement. They don't form joints with other bones.
Joints Overview
- A joint is formed when two or more bones come together.
- Joints allow movement, driven by muscles and gravity.
- They are classified as Synovial (diarthroses, freely moveable) or Solid (synarthroses, immovable, or amphiarthroses, slightly moveable).
- Synovial joints allow for greater movement than solid joints.
Synovial Joint Classifications
- Plane/Gliding joints allow for sliding movements with limited range of motion.
- Pivot joints allow movement on one axis, primarily rotation.
- Hinge joints enable movement on one axis, facilitating flexion and extension.
- Saddle joints permit movement on two axes at right angles, allowing flexion, extension, abduction, adduction, and circumduction.
- Ball and socket joints allow movement on multiple axes, providing a full range of motion including flexion, extension, abduction, adduction, circumduction, and rotation.
- Ellipsoid/Condyloid/Bicondylar joints allow movement in one axis, sometimes with limited rotation in a second axis.
Thorax Divisions
- The thorax is divided into: Right pleural cavity, Left pleural cavity, and Mediastinum.
- The mediastinal pleura encloses most of the mediastinum, connecting with the parietal pleura laterally and the pericardium internally.
Pleura Overview
- Each lung is enveloped within a pleural cavity.
Circulation: Overview
- Most major vessels are situated on the superior aspect of the heart, from right to left:
- Superior vena cava: Drains deoxygenated blood from the thorax, upper limbs, head, neck, and brain.
- Aortic arch: Originates from the ascending aorta, supplying the body with oxygenated blood.
- Pulmonary trunk: Carries deoxygenated blood from the heart to the lungs for oxygenation.
- Pulmonary veins: Leave the lungs with oxygenated blood, delivering it to the heart for circulation.
- Inferior vena cava: Drains deoxygenated blood from the abdomen and lower limbs.
Circulation: Coronary Circulation
- The heart receives oxygenated blood via the coronary circulation.
- Two coronary arteries, the left coronary artery and the right coronary artery arise from the ascending aorta and supply the heart.
- These arteries encircle the heart in the coronary sulcus, branching through the interventricular sulci towards the apex of the heart.
- Cardiac veins drain blood from the heart, primarily emptying into the coronary sinus, which lies on the posterior aspect of the heart and drains into the right atrium.
Conduction Overview
- Cardiac cycles start with signals from the SA node in the right atrium.
- The SA node transmits impulses to:
- Internodal tracts: Trigger contraction of the right atrium.
- Bachmann’s bundle: Stimulates contraction of the left atrium.
- AV node: Relays signals to the ventricles.
- The AV node transmits signals down the bundle of His, which splits into right and left bundle branches.
- Signals continue through the Purkinje fibers, stimulating the cardiac muscle to contract.
Urinary System Overview
- Urine production and osmoregulation occur in the kidneys.
- The ureters, bladder, and urethra are responsible for urine removal.
- The ureters extend from each kidney to the bladder.
- The bladder is a muscular bag that expands with urine and contracts to expel urine.
- The urethra transports urine from the bladder to the outside of the body.
Kidneys: Structure
- Each kidney contains nephrons, the functional units responsible for filtration and urine production.
- Nephrons primarily reside in the renal cortex, with varying degrees of extension into the medulla.
- The renal cortex surrounds the kidney and forms renal columns within the renal medulla.
- These columns divide the renal medulla into renal pyramids, triangular-shaped tissues that collect urine and transfer it to the minor calyces, then to the major calyces.
- The major calyces drain into the renal pelvis, the widened area of the kidney.
- The renal pelvis leaves the kidney at the hilum and narrows to become the ureter.
Urinary System: Relationships
- The kidneys are located in the retroperitoneal space of the abdomen, against the posterior abdominal wall.
- They are protected by the lower ribs, surrounding musculature, and viscera.
- The ureters travel retroperitoneally towards the bladder. They are sometimes narrower at specific points, which is clinically significant.
- The bladder lies in the pelvis:
- In males, it is directly anterior to the rectum.
- In females, it is directly anterior to the vagina and uterus.
Urethra: Males vs. Females
- The structure of the kidneys, ureters, and bladder is mostly similar between sexes.
- However, the female urethra is shorter than the male urethra.
- In males, the urethra is surrounded by the prostate before passing through the pelvic floor to the penis.
- In females, the urethra passes through the pelvic floor.
- The urethra has two associated muscles:
- Internal sphincter (involuntary smooth muscle): Keeps the bladder neck and urethra free of urine until pressure builds in the bladder.
- External sphincter (voluntary skeletal muscle): Controls urine release from the urethra.
Nervous: Overview
- The nervous system can be divided structurally into the:
- Central nervous system (CNS) - Brain and spinal cord
- Peripheral nervous system (PNS) - All nervous tissue outside the CNS
- Functionally, it can be divided into the:
- Somatic nervous system (SNS)
- Autonomic nervous system (ANS)
- The CNS acts as the control center, sending and receiving information through the PNS to and from muscles, glands, organs, and other systems.
Nervous: Divisions
- The nervous system is further divided into:
- Forebrain (prosencephalon):
- Cerebrum: Executive decisions, intellectual functions, memory, and movement coordination.
- Diencephalon: Thalamus, hypothalamus, pituitary gland, etc.
- Thalamus: Relay and processing center for sensory data.
- Hypothalamus: Controls emotions and hormone production.
- Midbrain (mesencephalon): Relay center for auditory and visual pathways, involved in motor movement, especially eye control.
- Hindbrain (rhombencephalon):
- Cerebellum: Maintains posture, balance, and equilibrium.
- Pons and Medulla oblongata: Relay information from the spinal cord to the cerebrum and cerebellum and contain autonomic centers for regulating visceral functions.
- Forebrain (prosencephalon):
Nervous: Terminology
- A collection of neuron cell bodies in the CNS is a nucleus.
- A collection of nerve cell bodies in the PNS is a ganglia (e.g., dorsal root ganglia and autonomic ganglia).
- A bundle of nerve fibers (axons) within the CNS connecting nuclei is a tract.
- A bundle of nerve fibers (axons) within the PNS is a nerve.
Nervous: Nerves
- There are 12 pairs of cranial nerves:
- Olfactory (I)
- Optic (II)
- Oculomotor (III)
- Trochlear (IV)
- Trigeminal (V)
- Abducens (VI)
- There are 31 pairs of spinal nerves:
- 8 Cervical
- 12 Thoracic
- 5 Lumbar
- 5 Sacral
- 1 Coccygeal
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Description
Test your knowledge on the human skeletal system and its components, including the types of bones and cartilage structure. This quiz covers essential functions of bones and how they contribute to the body's overall framework and health.
