Human Anatomy Flashcards

Question

Identify and describe this tissue

Answer 1

A - Simple Squamous (lung tissue) B - Simple Cuboidal (kidney) C - Simple Columnar (stomach) D - Transitional (Bladder) E - Stratified Squamous (Oesophagus) F - Stratified Cuboidal (Sweat gland) G - Stratified Columnar (Salivary duct) H - Simple Pseudostratified Columnar (trachea)

Answer 2

Corny Luck Granules Spin Basal

Answer 3

1. Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response 2. After several hours, a scab has formed and cells of the stratum basale are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving via the enhanced circulation in the area. Clotting around the edges of the affected area partially isolates the region 3. One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating 4. After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis

Answer 4

1. Cell disintegration: In holocrine secretion, the entire cell disintegrates to release its contents, including oils, lipids, or other substances. The cell ruptures, and its contents become the secretion. 2. Occurs in sebaceous glands: A prime example of holocrine secretion is in the sebaceous glands of the skin, which produce sebum to lubricate and protect the skin and hair. 3. Cell replacement: After the holocrine cells disintegrate, new cells are produced by mitosis to replace them, maintaining the cycle of secretion.

Answer 5

Sebaceous glands Sweat glands

Answer 6

Function: Primary role is to maintain the mineral content of the bone matrix and regulate bone turnover. They are critical for sensing mechanical stress in bones and relaying signals to other bone cells (osteoblasts and osteoclasts) to initiate bone formation or resorption as needed. They also help regulate the flow of nutrients and waste within the bone by extending cytoplasmic processes through canaliculi. Location: Osteocytes are embedded deep within the bone matrix inside small cavities called lacunae. The lacunae are interconnected by thin, tube-like channels known as canaliculi, allowing the osteocytes to communicate and share nutrients with neighbouring cells.

Answer 7

Function: Lacunae serve as protective cavities that _house osteocytes,_ keeping them isolated but connected to the larger network of bone tissue. They provide a structural niche where osteocytes can monitor bone integrity and communicate via the canaliculi system. Lacunae contribute to bone's ability to withstand stress and strain without losing function. Location: Lacunae are found throughout _both compact (cortical) and spongy (trabecular) bone._ They are small, hollow spaces within the bone matrix, scattered between the layers of _lamellae (concentric rings of bone tissue) in compact bone._

Answer 8

- Function: Osteoblasts are bone-forming cells responsible for producing the organic components of the bone matrix, primarily collagen type I, which forms the bone’s framework. They initiate the mineralization process by depositing calcium and phosphate into the matrix, leading to the hardening of bone tissue. Their activity is regulated by hormones like parathyroid hormone (PTH) and growth factors. - Location: Osteoblasts are typically found on the surface of bone tissue, in regions of active bone formation, such as growth plates, the periosteum (the outer layer of bone), and regions undergoing repair. They are particularly active during childhood and adolescence when bone growth is rapid.

Answer 9

- Function: Osteoclasts are large, multinucleated cells responsible for breaking down bone tissue during the process of bone resorption. They dissolve the mineral and organic components of bone by secreting acids and proteolytic enzymes, which release calcium and phosphate into the bloodstream. This process is essential for bone remodelling, growth, and the regulation of blood calcium levels. - Location: Osteoclasts are typically found on the surface of bones in regions undergoing active resorption. They are particularly prevalent in areas undergoing remodelling, such as near fractures or along trabecular bone in the spongy region.

Answer 10

- Function: Osteoprogenitor cells are stem cells capable of differentiating into osteoblasts, which are responsible for new bone formation. These precursor cells are crucial for bone development, growth, and repair, particularly after fractures or other injuries. They also play a role in the normal turnover of bone tissue by providing a continuous supply of osteoblasts for bone maintenance. - Location: Osteoprogenitor cells are located in the inner layer of the periosteum, the endosteum (the lining of the marrow cavity), and in the bone marrow. They are most active during growth periods, healing, or bone remodeling.

Answer 11

1. Pectoral girdle (clavicle , scapula) 2. Upper limb 3. Pelvic girdle (supporting bones and sacrum) 4. Lower limb

Answer 12

Skull Sternum Ribs Vertebrae Sacrum Super sharp razors vanquish soldiers

Answer 13

osteon Haversian system lamellae Haversian

Answer 14

1. Location - Periosteum: Outer surface of bones (except at joints). - Endosteum: Inner surface of bones, lining the medullary cavity and spongy bone spaces. 2. Structure - Periosteum: Two layers: * Outer fibrous layer (collagen-rich). * Inner osteogenic layer (contains osteoblasts and osteoclasts). - Endosteum: * Thin, single layer of cells (osteoblasts and osteoclasts). 3. Function - Periosteum: * Provides attachment for muscles and tendons. * Supplies blood to the bone. Involved in bone growth and repair. - Endosteum: * Participates in bone remodeling. * Maintains the inner bone structure and medullary cavity.

Answer 15

1. Definition - Appositional: Increases bone thickness. - Interstitial: Increases bone length. 2. Location - Appositional: Periosteum (outer surface). - Interstitial: Epiphyseal plate (growth plate). 3. Process - Appositional: Osteoblasts add new bone on the outside. - Interstitial: Chondrocytes expand cartilage from within. 4. Outcome - Appositional: Thickens bones; continues for life. - Interstitial: Lengthens bones; stops after puberty

Answer 16

1. Definition - Circular layers of calcified bone matrix arranged around a central canal (Haversian canal) in compact bone, forming an osteon. 2. Function - Provide strength and structure to bones. - Resist twisting and compressive forces. - House osteocytes in lacunae for bone maintenance. 3. Location - Found in osteons, the cylindrical units of compact bone, surrounding the Haversian canal. 4. Structure - Collagen fibers in each layer are oriented in different directions to resist fractures and mechanical stress

Answer 17

Definition: - Interstitial lamellae are remnants of old osteons that have been partially resorbed during the process of bone remodeling. They fill the spaces between newly formed osteons in compact bone. Function: - Interstitial lamellae provide additional strength to the bone by filling in the gaps between osteons, making the bone more solid and cohesive. They help maintain the structural integrity of compact bone. - Location: Interstitial lamellae are found between osteons in compact bone, filling the spaces that would otherwise be empty. These remnants are irregularly shaped and incomplete compared to the concentric lamellae of osteons. - Structure: They consist of fragments of lamellae that do not form a complete circular structure, as they are the remnants of previously resorbed osteons

Answer 18

1. Description - Trabeculae are the thin, needle-like or plate-like structures that form the network within spongy (cancellous) bone. They consist of lamellae with embedded osteocytes, and are oriented along lines of stress to provide structural support. 2. Why They Make Bones "Spongy" - Trabeculae create a porous, lattice-like structure with many spaces in between. These spaces are often filled with bone marrow (red or yellow) and blood vessels. The porous nature of this network gives spongy bone a lightweight and spongy appearance while still providing strength and support to the bone

Answer 19

1. Hormones: Growth hormone (GH), thyroid hormone, and sex hormones (estrogen and testosterone) stimulate bone growth and development, especially during puberty. 2. Nutrients: Adequate intake of calcium, phosphorus, and vitamin D is crucial for bone mineralization and strength. 3. Mechanical Stress: Physical activity and weight-bearing exercises stimulate bone remodeling and increase bone density. 4. Genetics: Genetic factors determine the overall size and shape of bones, as well as the peak bone mass one can achieve.

Answer 20

Description: Small, flat, irregular bones found between the flat bones of the skull Example: Sutures of the skull (e.g., between parietal bones) Function: Fill gaps in the skull and add strength to the structure

Answer 21

Description: Complex-shaped bones with irregular surfaces Example: Vertebrae, pelvic bones Function: Provide protection, support, and attachment for muscles

Answer 22

Description: Cube-like bones with equal length, width, and thickness Example: Carpals (wrist bones), tarsals (ankle bones) Function: Provide stability and support with limited movement

Answer 23

Description: Bones that are hollow or contain air-filled spaces (sinuses) Example: Ethmoid bone (in the skull) Function: Reduce bone weight and enhance voice resonance

Answer 24

Description: Thin, flattened bones with parallel surfaces Example: Skull, ribs, sternum, scapula Provide protection for internal organs and muscle attachment

Answer 25

Description: Long, cylindrical bones with expanded ends Example: Femur, humerus, tibia, radius Function: Support body weight and facilitate movement

Answer 26

Sesamoid bones are small, round structures that are embedded within tendons, typically found at locations where tendons cross over joints, such as the patella (kneecap) in the knee and the flexor hallucis brevis in the foot. These bones serve several important functions: they help to reduce friction between the tendon and the underlying bone, enhance the leverage of the muscles by altering the direction of tendon pull, and distribute stress across the joint during movement, which can help protect the tendon from wear and injury. By improving the mechanical efficiency of the musculoskeletal system, sesamoid bones play a crucial role in facilitating smooth and effective joint function

Answer 27

A demifacet is a half-sized facet on a vertebra that forms part of a joint. It is a small, flat surface on the side of a vertebral body where the head of a rib connects. These demifacets allow ribs to articulate with two adjacent vertebrae. Example: In the thoracic vertebrae (specifically T2 through T9), there are superior and inferior demifacets. For example, the T6 vertebra has a superior demifacet that articulates with the head of the sixth rib and an inferior demifacet that articulates with the head of the seventh rib.

Answer 28

The glenoid cavity articulates with the head of the humerus. This articulation forms the shoulder joint, also known as the glenohumeral joint, which allows for a wide range of arm movements.

Answer 29

- Carpometacarpal joint Connects the metacarpals to the distal carpals - Intercarpal joint Connects one carpal bone to another - Metacarpophalangeal joint Connects metacarpals to the proximal phalanges -Interphalangeal joint Joint between the proximal, middle, & distal phalanges

Answer 30

roots - trunks - divisions - cords - nerves

Answer 31

Epimysium Endomysium Perimysium The collagen fibres of all three layers come together to form a tendon that attaches the muscle to bone, cartilage, skin or another muscle

Answer 32

- Layer of dense irregular connective tissue surrounding the entire skeletal muscle Separates the muscle from surrounding tissues and organs and is connected to the deep fascia - A fascia is a sheath of stringy connective tissue that surrounds every part of your body. It provides support to your muscles, tendons, ligaments, tissues, organs, nerves, joints and bones.

Answer 33

Divide the muscle into internal compartments each of which contains a bundle of muscle fibres called a fascicle. Contains collagen and elastic fibres, and numerous blood vessels and nerves supply each fascicle

Answer 34

- Surrounds each individual muscle cell and bind each muscle fibre to its neighbour as well as supports the capillaries that supply the individual fibre - Scattered myosatellite cells, which are cells that differentiate and become skeletal cells, lie between the endomysium and the muscle fibres

Answer 35

muscle bone aponeuroses

Answer 36

The endomysium

Answer 37

sarcolemma sarcoplasm

Answer 38

myosatellite cells

Answer 39

Transverse tubules (T tubules)

Answer 40

sarcoplasmic reticulum

Answer 41

terminal cisternae triad

Answer 42

3, 1, 5 , 4, 2

Answer 43

1. Actin – The primary protein that forms the backbone of the thin filament. It provides binding sites for myosin during muscle contraction. 2. Tropomyosin – A protein that wraps around the actin filament, blocking the myosin-binding sites on actin when the muscle is relaxed. 3. Troponin – A complex of three proteins (Troponin T, Troponin I, and Troponin C) that regulate the position of tropomyosin and, consequently, the access of myosin to actin. It binds calcium ions to trigger muscle contraction. 4. Nebulin – A large protein that is associated with the actin filament and helps to stabilise its structure, although its role is not as prominent as the other three

Answer 44

- Myosin Molecules – The thick filament is primarily made up of hundreds of myosin molecules. Each myosin molecule has two main parts: - Myosin Heads: These are the globular heads of myosin that extend outward from the filament. Each head contains an actin-binding site and an ATPase site that hydrolyzes ATP to provide energy for muscle contraction. - Myosin Tails: The long, rod-like tail regions of myosin molecules bundle together to form the backbone of the thick filament. - Arrangement – The myosin molecules are arranged in a staggered, overlapping fashion. The heads of myosin protrude outwards at regular intervals, creating a pattern that allows them to interact with the actin filaments during muscle contraction. These heads are oriented in opposite directions at either end of the filament.

Answer 45

cross-bridges

Answer 46

A motor unit is a single motor neuron and all of the muscle fibres it controls. Some motor neurons control a single muscle fibre, but most control hundreds. The smaller the size of a motor unit, the finer the control of movement will be. In the eye, where precise muscular control is critical, a motor neuron may control only two or three muscle fibres. We have less precise control over power-generating muscles, such as our leg muscles, where a single motor neuron may control up to 2000 muscle fibres

Answer 47

muscle tone

Answer 48

Muscle spindles

Answer 49

Hypertrophy Atrophy

Answer 50

Slow (red) Fast (white) Intermediate

Answer 51

= Small diameter and take up to 3x as long to contract Specialised to continue contracting for long times Fatigue slowly bcuz their mitochondria continue producing ATP throughout the contraction process = Utilise aerobic metabolism which requires oxygen from two different sources: Skeletal muscles containing slow muscle fibres have a larger network of capillaries than muscles dominated by fast muscle fibres. This means that there is greater blood flow to the muscle, and the red blood cells can deliver more oxygen to the active muscle fibres. = Slow fibres are red because they contain the red pigment myoglobin (MĪ-ō-glō-bin). This globular protein, like haemoglobin (the oxygen-binding pigment found in red blood cells), binds oxygen molecules. As a result, slow muscle fibres contain large oxygen reserves that are mobilised during a contraction.

Answer 52

= Have a large diameter = Densely packed myofibrils = Large glycogen reserves = Relatively few mitochondria = Contract quickly upon stimulation = Tension produced is directly proportional to the number of myofibrils, however the contractions use large amounts of ATP and are supported primarily by anaerobic metabolism (glycolysis) = Glycolysis does not require oxygen and converts stored glycogen to lactic acid. Fast fibres fatigue rapidly because their glycogen reserves are limited and because lactic acid builds up and the resulting acidic pH interferes with the contraction mechanism.

Answer 53

Have properties between those of fast and slow fibres. For example, intermediate fibres contract faster than slow fibres but slower than fast fibres

Answer 54

- Muscle fibres run parallel to the long axis of the muscle. - Tend to have a relatively uniform width and can contract over a greater distance, though they typically generate less force compared to other muscle types. - Muscle fibres are aligned along the direction of pull, usually in a straight line. - They can be flat (e.g., rectus abdominis) or spindle-shaped with a thicker belly and tapered ends (e.g., biceps brachii).

Answer 55

- Fibres are spread out over a broad area but converge toward a single point or tendon. - Versatile movement as the muscle can pull in different directions depending on which fibres are activated. - Spread out from a wide origin (often broad and fan-shaped) and converge to a _single point,_ typically at a tendon or a small insertion. - Often have a triangular or fan-like shape. Like the pecs.

Answer 56

- Muscles where the fibres are arranged obliquely to their tendons, resembling a feather. This arrangement allows for a greater number of fibres in a given area, which helps increase the force of contraction, although the range of motion is reduced compared to parallel muscles. - The muscle fibres attach diagonally to a central tendon, resembling the structure of a feather. Depending on how the fibres are arranged, they can be classified into three types - Pennate muscles generate high force but have a limited range of motion due to their angled fibre arrangement.

Answer 57

* Unipennate: Fibres are on one side of the tendon (e.g., extensor digitorum). * Bipennate: Fibres are on both sides of the tendon (e.g., rectus femoris). * Multipennate: Multiple tendons with fibres attaching from different angles (e.g., deltoid). Shape: The feather-like arrangement can vary depending on whether it's unipennate, bipennate, or multipennate.

Answer 58

- A circular muscle, or sphincter, the fibres are concentrically arranged around an opening . When the muscle contracts, the diameter of the opening decreases. An example is the orbicularis oris of the mouth

Answer 59

origin insertion

Answer 60

= Agonist (Prime Mover): This is the main muscle responsible for producing a specific movement. It provides the majority of the force. For example, during elbow flexion, the biceps brachii acts as the agonist. = Antagonist: This muscle opposes the action of the agonist. It helps control or slow down the movement, and it relaxes when the agonist contracts. For instance, in elbow flexion, the triceps brachii is the antagonist. = Synergist: These muscles assist the agonist by adding extra force or reducing unwanted movements. They help stabilise joints and ensure smooth movement. An example is the brachialis, which assists the biceps during elbow flexion. = Fixator (Stabiliser): Fixators stabilise the origin of the agonist so that it can work more efficiently. They hold certain body parts steady while the movement occurs. For example, the muscles of the shoulder girdle act as fixators during arm movements.

Answer 61

Effort Load Fulcrum

Answer 62

= First-class lever: The fulcrum is between the effort and the load (e.g., neck movement, where the atlanto-occipital joint is the fulcrum, neck muscles provide effort, and the head is the load). = Second-class lever: The load is between the fulcrum and the effort (e.g., standing on tiptoes, with the ball of the foot as the fulcrum, body weight as the load, and calf muscles providing effort). = Third-class lever: The effort is between the fulcrum and the load (e.g., elbow flexion, with the elbow as the fulcrum, biceps applying effort, and the forearm and hand as the load).

Answer 63

Pulleys change the direction of muscle force. For example, the patella acts as a pulley, redirecting the force of the quadriceps tendon to improve the efficiency of leg extension at the knee.

Answer 64

See also, the homonculus and how it looks

Answer 65

- Affectors, like nociceptors, transmit pain signals when the skin is damaged, alerting the body to potential harm. - Thermoreceptors in the skin send temperature-related information to the brain, helping regulate body heat. - Mechanoreceptors, such as those in the fingertips, detect pressure or texture changes and relay these sensations for fine motor control or object recognition.

Answer 66

- Day 20–21: Formation of the Neural Plate Neural Plate Formation: Around day 20, the ectoderm, which is the outermost layer of the embryonic tissue, thickens along the dorsal midline, forming the neural plate. This thickening marks the beginning of nervous system development. Somite Formation: At the same time, mesodermal tissue on either side of the neural plate forms paired blocks called somites. These somites are critical for later development of the vertebrae, skeletal muscles, and dermis. - Day 22–24: Neural Groove and Neural Fold Neural Groove: The neural plate starts to invaginate (fold inwards), forming a groove along its midline called the neural groove. Neural Folds: The lateral edges of the neural plate rise, forming neural folds. These folds will eventually come together and fuse. - Day 25–26: Neural Tube Formation Closure of the Neural Tube: By about day 25, the neural folds begin to fuse in the middle and zip up in both directions, eventually creating a hollow structure called the neural tube. The neural tube is the precursor to the brain and spinal cord. Neural Crest Cells: As the neural tube closes, cells at the edges of the neural folds, known as neural crest cells, begin to migrate away. These cells will give rise to various structures, including peripheral nerves and other specialised cell types. - Day 27–30: Early Brain and Spinal Cord Development Formation of Brain Regions: By day 28, the anterior portion of the neural tube starts to develop into the primary brain vesicles—prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain). Spinal Cord Formation: The remainder of the neural tube, extending caudally from these vesicles, begins differentiating into the spinal cord. - At day 30, the basic structure of the central nervous system has been established, with regional specialisation evident in the brain and spinal cord.

Answer 67

The prosencephalon, or forebrain, is the most anterior part of the developing brain. It later subdivides into the telencephalon and diencephalon. The telencephalon gives rise to the cerebral cortex and basal ganglia, responsible for complex functions such as cognition, sensory processing, and voluntary movement. The diencephalon forms structures like the thalamus and hypothalamus, which regulate autonomic functions, hormone release, and act as a relay station for sensory information.

Answer 68

The telencephalon is the most anterior part of the forebrain and eventually forms the cerebral cortex, basal ganglia, and limbic system. The cerebral cortex is responsible for higher cognitive functions, including thought, language, memory, and perception. The basal ganglia play a key role in movement control and reward processing, while the limbic system (including the hippocampus and amygdala) is critical for emotion regulation and memory formation.

Answer 69

The diencephalon lies just beneath the telencephalon and differentiates into the thalamus, hypothalamus, epithalamus, and subthalamus. The thalamus acts as a relay station, directing sensory information to the appropriate areas of the cortex. The hypothalamus regulates homeostatic processes, including hunger, temperature, and circadian rhythms, and controls hormone release through the pituitary gland. Together, these structures help integrate sensory input with bodily functions and emotional responses.

Answer 70

Mesencephalon (Midbrain) The mesencephalon, or midbrain, lies between the forebrain and hindbrain and is a relatively smaller region. It plays a crucial role in processing auditory and visual information and controlling motor movements. The midbrain houses structures like the tectum and tegmentum, which coordinate eye movements, reflexes to visual and auditory stimuli, and basic functions related to arousal and alertness. * The mesencephalon does not subdivide, but its walls thicken and the neurocoel becomes a narrow passageway with a diameter similar to that of the central canal of the spinal cord.

Answer 71

The rhombencephalon, or hindbrain, is the posterior part of the brain and subdivides into the metencephalon and myelencephalon. The metencephalon develops into the pons and cerebellum, essential for coordinating movement and maintaining balance. The myelencephalon forms the medulla oblongata, which controls vital autonomic functions like breathing, heart rate, and blood pressure. Together, these structures support essential survival functions and smooth motor control.

Answer 72

The metencephalon is a part of the hindbrain that develops into the pons and cerebellum. The pons functions as a communication hub, linking various parts of the brain and playing a role in sleep and respiration. The cerebellum coordinates voluntary motor activities, fine-tuning movement and maintaining balance and posture. It also contributes to motor learning and cognitive functions, such as attention and language processing.

Answer 73

The myelencephalon is the most caudal part of the hindbrain, forming the medulla oblongata. The medulla regulates essential autonomic functions, including heart rate, blood pressure, and respiratory rhythms. It serves as a pathway for neural signals between the brain and spinal cord and houses reflex centres that control actions like swallowing, coughing, and sneezing. This structure is crucial for basic survival functions

Answer 74

medulla oblongata

Answer 75

mesencephalon

Answer 76

diencephalon epithalamus thalamus hypothalamus

Answer 77

cerebellum

Answer 78

cerebrum cerebral cortex sulci gyri

Answer 79

In the brain, gray matter forms an inner region surrounded by white matter tracts. This structure surrounds fluid-filled ventricles and passageways that connect to the spinal cord’s central canal. Much like in the spinal cord, the brain’s white matter encases regions of gray matter, which appear as nuclei, or clusters of neuron cell bodies, with various shapes. However, gray and white matter arrangements in the brain are more complex than in the spinal cord. In the cerebrum and cerebellum, white matter is covered by a superficial gray matter layer called the cortex.

Answer 80

higher centres

Answer 81

Consists of four fluid-filled chambers called ventricles, which contain cerebrospinal fluid (CSF) and are lined by ependymal cells. There are two lateral ventricles, one in each cerebral hemisphere, a third ventricle located within the diencephalon, and a fourth ventricle situated between the pons and cerebellum, extending into the upper part of the medulla oblongata. Each ventricle plays a role in circulating CSF, which helps cushion the brain and supports its metabolic functions

Answer 82

lateral septum pellucidum third ventricle

Answer 83

cerebral aqueduct Cerebrospinal fluid (CSF)

Answer 84

1. Dura mater 2. Arachnoid mater 3. Pia mater

Answer 85

Two Fibrous Layers: - Outermost Layer: Periosteal cranial dura * Attached to the periosteum of cranial bones. - Innermost Layer: Meningeal cranial dura Space Between Layers: - Filled with interstitial fluid and blood vessels (including dural sinuses). - Dural Sinuses: Collect blood from brain veins before draining into the internal jugular veins in the neck. Meningeal Dura Folds: - Occurs at four specific sites within the cranial cavity. - Creates partitions to support the brain and limit its movement. Structural Importance: - Stabilises brain position and ensures proper blood drainage.

Answer 86

Is a sickle-shaped fold of dura mater located between the cerebral hemispheres in the longitudinal fissure. It attaches anteriorly to the crista galli and posteriorly to the internal occipital crest and tentorium cerebelli, containing two major venous sinuses: the superior sagittal sinus and the inferior sagittal sinus.

Answer 87

Acts as a protective covering for the occipital lobes of the cerebrum and separates the cerebellar hemispheres from the cerebrum, extending across the skull at right angles to the falx cerebri. It houses the transverse sinus within its structure.

Answer 88

subarachnoid space arachnoid granulations trabeculae

Answer 89

A highly vascular membrane that tightly adheres to the brain's surface, conforming to its contours and lining the sulci. It is anchored to the brain by the extensions of astrocytes, which help maintain its attachment. The pia mater serves as a supportive floor for large cerebral blood vessels, allowing them to branch and follow the brain's convolutions. This close association ensures that the superficial areas of the cerebral cortex receive an adequate blood supply, which is crucial for brain function and health.

Answer 90

- The blood-brain barrier (BBB) is a critical mechanism that isolates the central nervous system (CNS) from general circulation, ensuring a stable environment essential for proper neuronal function and control. - It is formed by capillary endothelial cells that are tightly interconnected by tight junctions, preventing the diffusion of materials between cells and allowing only lipid-soluble compounds to pass into the brain's interstitial fluid.

Answer 91

pinocytotic

Answer 92

Astrocytes

Answer 93

selective directional

Answer 94

- Increased Permeability for Hormone Sensing: The hypothalamus contains permeable capillaries that allow access to circulating hormones, enabling direct detection of blood-borne signals, like glucose and electrolyte levels, critical for homeostasis. - Direct Influence on Blood Chemistry: This permeability facilitates the release of hypothalamic hormones (e.g., TRH, GnRH) directly into the bloodstream, helping regulate vital body processes like metabolism and reproduction. - Selective Monitoring and Exception to the BBB: Unlike other brain regions shielded by the BBB, the hypothalamus monitors blood for factors such as osmolarity, temperature, and nutrients, allowing rapid adjustments in bodily functions via neuroendocrine signalling.

Answer 95

- High Capillary Permeability: The pineal gland capillaries are highly permeable, allowing hormones, particularly melatonin, to enter circulation unimpeded, coordinating sleep-wake cycles and seasonal biological rhythms. - Regulation of Circadian Rhythms: By directly releasing melatonin into the bloodstream, the pineal gland influences sleep cycles and circadian rhythms, especially in response to light exposure patterns. - Endocrine Communication Beyond the BBB: Unlike BBB-protected areas, the pineal gland freely communicates with the systemic circulation, providing feedback on circadian and seasonal changes that inform CNS and endocrine responses.

Answer 96

- Direct Hypothalamic Connection: The posterior pituitary lacks a BBB, allowing it to act as an extension of the hypothalamus, enabling fast transport of neurohormones like antidiuretic hormone (ADH) and oxytocin. - Rapid Response Hormone Release: Hormones such as ADH (which controls water balance) and oxytocin (affecting uterine contractions and lactation) are released directly into the bloodstream, providing immediate physiological responses. - Neuroendocrine Coordination: The posterior pituitary’s design ensures it works in sync with the hypothalamus, acting as a hub for hormone release, bypassing the BBB to regulate blood volume, stress responses, and reproductive functions.

Answer 97

- Primary Site of CSF Production: The choroid plexus, located in the third and fourth ventricles, produces cerebrospinal fluid (CSF) which circulates within the CNS, providing cushioning and nutrient transport. - Selective Blood–CSF Barrier: Specialized ependymal cells within the choroid plexus form a barrier, filtering blood and controlling the entry of ions, vitamins, and nutrients into the CSF, similar to BBB selectivity. - Dual Protective Role: The choroid plexus prevents toxins and pathogens from reaching the CNS through blood vessels, adding another layer of defense that complements the BBB in protecting the brain’s microenvironment.

Answer 98

- Physical Protection for Neural Tissue: CSF surrounds the brain and spinal cord, absorbing shocks and preventing delicate neural tissues from making direct contact with the skull, acting as a cushion against physical impacts. - Chemical Stability and Environmental Control: The BBB and CSF together maintain an optimal environment for neurons by controlling ion concentration, nutrient levels, and waste, safeguarding the brain from blood composition fluctuations. - Efficient Nutrient and Waste Transport: CSF allows regulated movement of vital compounds while isolating harmful substances, thereby maintaining the delicate ionic balance required for nerve impulses, functioning alongside the BBB to keep CNS tissues in ideal condition.

Answer 99

- Filtration via Choroid Plexus: CSF is filtered from blood within the choroid plexus through specialized ependymal cells that prevent large molecules and harmful substances from entering the brain’s ventricles, maintaining BBB-like selectivity. - Control of Ion and Nutrient Exchange: Ependymal cells regulate the entry of ions and other compounds into CSF, protecting CNS tissues from fluctuations in blood chemistry, in tandem with the BBB’s selective permeability. - Efficient Production and Renewal of CSF: The choroid plexus produces 500 mL of CSF daily, with the total CSF volume being replaced every 8–12 hours, ensuring fresh, filtered fluid circulates continuously, removing waste and maintaining a stable internal environment.

Answer 100

- CNS Pathways and CSF Circulation: CSF flows from the lateral ventricles to the third and fourth ventricles, then into the subarachnoid space, providing a medium for nutrient distribution and waste removal throughout the CNS. - Selective Reabsorption Mechanism: CSF is reabsorbed into the bloodstream via arachnoid granulations, which prevent large molecules from entering the CSF, preserving the brain’s protected environment similarly to the BBB. - Minimised Direct Blood Exposure: CSF reabsorption carefully limits the brain’s contact with blood, reducing exposure to blood-borne toxins or pathogens and supporting the BBB’s role in maintaining CNS isolation.

Answer 101

1. Protection: CSF prevents contact between delicate neural structures and surrounding bones, reducing the risk of injury from mechanical forces. 2. Support: The brain is essentially suspended within the cranium, floating in CSF. Although a human brain weighs about 1,400 grams in air, its effective weight is reduced to about 50 grams when supported by CSF. 3. Transport: CSF facilitates the movement of nutrients, chemicals, and waste products. The ependymal lining is generally permeable, allowing CSF to maintain constant chemical communication with the interstitial fluid of the CNS.

Answer 102

- Many ascending sensory and descending motor tracts synapse in sensory or motor nuclei within the medulla. Key nuclei include the gracile and cuneate nuclei, which relay somatic sensory information to the thalamus, and the solitary nucleus, which receives visceral sensory information. The olivary nuclei relay information from various brain regions to the cerebellar cortex and form the prominent olives on the medulla's surface

Answer 103

The medulla contains sensory and motor nuclei for five cranial nerves (VIII, IX, X, XI, and XII). These cranial nerves innervate muscles in the pharynx, neck, and back, as well as visceral organs in the thoracic and abdominopelvic cavities.

Answer 104

- The reticular formation includes nuclei that regulate vital autonomic functions. Major centers include: * Cardiovascular Centers: Adjust heart rate, cardiac contraction strength, and blood flow to tissues. They consist of cardiac and vasomotor centers. * Respiratory Rhythmicity Centers: Set the basic breathing pace, regulated by inputs from apneustic and pneumotaxic centers in the pons.

Answer 105

The pons is a key structure in the brainstem involved in various essential functions. It acts as a relay centre, connecting the cerebrum and cerebellum, which facilitates coordination of voluntary movements. It also plays a critical role in autonomic functions such as regulating breathing patterns. Additionally, the pons houses nuclei (pneumotaxic, apneustic) involved in sensory information processing and cranial nerve functions, such as facial sensation, hearing, and eye movement

Answer 106

1. Longitudinal tracts connect the pons to other CNS areas. 2. Anterior cerebellar peduncles contain efferent cerebellar tracts for interhemispheric communication. 3. Inferior cerebellar peduncles consist of both afferent and efferent tracts connecting the cerebellum with the medulla oblongata.

Answer 107

The posterior surface of the mesencephalon is known as the tectum, which contains two pairs of sensory nuclei, collectively referred to as the corpora quadrigemina: Superior Colliculi: - Visual processing - Coordination of eye movements (saccades) - Multisensory integration (visual, auditory, and somatosensory) - Visual attention and orienting behavior Inferior Colliculi: - Auditory processing - Sound localization - Auditory reflexes (startle reflex) - Relay point for auditory information to the thalamus and auditory cortex

Answer 108

- Superior Colliculi: These nuclei are involved in processing visual information. They receive input primarily from the lateral geniculate nucleus of the thalamus on the ipsilateral side and are important for reflexive movements of the eyes and head in response to visual stimuli. - Inferior Colliculi: These nuclei process auditory information received from the medulla oblongata. They play a key role in reflexive responses to sound and relay auditory signals to the medial geniculate nucleus in the thalamus for further processing.

Answer 109

- The mesencephalon contains significant nuclei of the reticular formation, which is involved in various involuntary motor responses and contributes to the regulation of wakefulness and alertness. Stimulation of this region can produce diverse motor responses, including reflexive actions.

Answer 110

- Red Nucleus: This nucleus has a rich vascular supply, giving it a reddish appearance. It processes information from both the cerebrum and cerebellum and is involved in issuing involuntary motor commands that help maintain muscle tone and limb position. It plays a role in coordination and motor control. - Substantia Nigra: Located lateral to the red nucleus, this area contains darkly pigmented neurons that are critical for motor regulation. Regulates voluntary motivated movement. Dopamine influences the behviour of the movement, works to avoid doing _unwanted_ movement

Answer 111

The cerebral peduncles are prominent structures on the ventrolateral surfaces of the mesencephalon. They contain: * Ascending fibre: These fibre transmit sensory information to the thalamus, allowing the brain to process sensory input from various parts of the body. * Descending fibre: These fibre carry voluntary motor commands from the primary motor cortex of each cerebral hemisphere through the corticospinal pathway. They play a crucial role in executing voluntary movements by relaying signals from the brain to the spinal cord.

Answer 112

- The diencephalon comprises about 2% of the grey matter in the central nervous system (CNS), yet it plays a crucial role due to its extensive connections. Almost all motor and sensory systems in the CNS synapse within this region. - The diencephalon serves as a link between the brainstem and the cerebral hemispheres, consisting of the epithalamus, the left and right thalamus, and the hypothalamus. Various figures illustrate the diencephalon's position and its relation to other brain structures.

Answer 113

- The epithalamus forms the roof of the third ventricle and houses the pineal gland. The epithalamus includes a membranous anterior section with a choroid plexus that extends through the interventricular foramina into the lateral ventricles. Its posterior part contains the pineal gland, an endocrine organ responsible for secreting melatonin. - Melatonin is believed to regulate circadian rhythms, and may also influence reproductive functions.

Answer 114

- Largest Nuclei Collection: The thalamus is the CNS’s largest nuclei group, integrating and relaying sensory and motor information. - Diencephalon Structure: Comprises most of the diencephalon's tissue, forming lateral walls around the third ventricle. - Sensory Relay Centre: Almost all ascending sensory data (except olfactory and spinocerebellar) synapse in the thalamus before reaching the cerebrum or brainstem. - Filtering Function: Acts as the final synapse for sensory input to the primary somatosensory cortex, filtering and selectively transmitting sensory data. - Motor Coordination: Regulates motor activities at conscious and subconscious levels.

Answer 115

1. Control of Skeletal Muscle Contractions: Directs motor patterns linked to emotions such as rage and pleasure. 2. Regulation of Autonomic Functions: Coordinates autonomic centres that manage heart rate, blood pressure, respiration, and digestion. Integration of Nervous and 3. Endocrine Systems: Influences endocrine activity in the pituitary gland. 4. Hormone Secretion: Produces antidiuretic hormone (ADH) and oxytocin, which are released into the bloodstream. 5. Emotional and Behavioural Drives: Triggers sensations that alter behaviour, such as thirst. 6. Voluntary and Autonomic Coordination: Monitors cerebral activities to adjust autonomic responses during stress. 7. Body Temperature Regulation: Controls physiological responses to maintain temperature. 8. Circadian Rhythms: Coordinates daily activity cycles in response to light, adjusting related brain and gland functions

Answer 116

46-63% 37-54%

Answer 117

92% water 7% plasma proteins 1% other solutes

Answer 118

1. Albumins: * Percentage: About 60% of plasma proteins. * Function: Key contributors to osmotic pressure, helping to maintain fluid balance in the blood. They also transport fatty acids, thyroid hormones, and some steroid hormones. 2. Globulins: * Percentage: Roughly 35% of plasma proteins. * Types: Includes immunoglobulins (antibodies) that support immune defence, and transport globulins that bind small ions and hormones, especially those that are insoluble or would be filtered out by the kidneys. 3. Fibrinogen: * Percentage: Approximately 4% of plasma proteins. * Function: The largest plasma protein, crucial for blood clotting. Fibrinogen converts to fibrin, forming the structural framework of a blood clot. If blood is not treated to prevent clotting, fibrinogen is transformed into fibrin, resulting in serum when clotting proteins are removed.

Answer 119

Whole blood comprises plasma and formed elements, and its viscosity is significantly higher than that of water—five times more viscous—due to interactions among proteins and cells. Blood volume can be estimated at about 7% of body weight; for example, a 75-kg person has approximately 5.25 litres of blood. Blood is slightly alkaline, with a pH between 7.35 and 7.45, and a temperature of about 38°C. Terms like hypovolemic, normovolemic, and hypervolemic describe low, normal, and excessive blood volumes, respectively, which can impact health, particularly in conditions like kidney failure.

Answer 120

- Definition: A condition of low blood volume. - Causes: Results from blood loss (trauma, surgery), severe dehydration (vomiting, diarrhoea), or conditions like diabetes insipidus. - Consequences: Leads to low blood pressure, reduced organ perfusion, and shock. Symptoms include weakness, dizziness, rapid heart rate, and confusion.

Answer 121

- Definition: A state of normal blood volume. - Significance: Essential for maintaining blood pressure and adequate tissue perfusion. Indicates a balance between blood production and loss. - Clinical Relevance: Vital in surgeries and critically ill patients, where monitoring fluid balance is crucial to avoid complications.

Answer 122

- Definition: An excess of blood volume. - Causes: Occurs due to fluid retention from heart failure, kidney dysfunction, excessive salt intake, or overadministration of IV fluids. - Consequences: Can lead to high blood pressure and strain on the heart, causing heart failure or edema. Symptoms include shortness of breath, swelling, and hypertension.

Answer 123

- Structure and Function: Red blood cells (RBCs) are anucleate, biconcave discs that transport oxygen and carbon dioxide, constituting nearly half of blood volume. Their shape increases surface area for gas exchange and allows them to stack and pass through narrow capillaries smoothly. - Cellular Adaptations: RBCs lack most organelles, relying on anaerobic metabolism from plasma glucose, ensuring oxygen is transported to tissues. Their 120-day lifespan is due to the inability to repair damaged enzymes or proteins. - Haemoglobin Role: Haemoglobin (Hb) comprises over 95% of RBC protein, with each molecule binding iron to transport oxygen. Oxyhemoglobin gives blood a bright red colour, while deoxygenated blood appears dark red.

Answer 124

- Erythropoiesis Process: RBC formation (erythropoiesis) occurs mainly in adult red bone marrow, especially in the vertebrae, sternum, and pelvis. In extreme cases, yellow marrow can convert to red marrow to increase RBC production. - Nutritional Requirements: Amino acids, iron, and vitamin B12 are essential for proper erythropoiesis. - EPO Regulation: Erythropoietin (EPO), produced by the kidneys and liver in response to low oxygen, stimulates cell division in erythroblasts and speeds up RBC maturation. Under peak conditions, bone marrow can produce up to 30 million RBCs per second.

Answer 125

A cross-reaction occurs when an antibody meets its specific surface antigen (Figure 20.4b). First, the red blood cells clump together, a process called agglutination (a-glū-ti-NĀ-shun). The RBCs may also hemolyze (rupture). The clumps and fragments of RBCs under attack form drifting masses that can plug small blood vessels in the kidneys, lungs, heart, or brain, damaging or destroying affected tissues. To avoid cross-reactions, the blood types of the donor and recipient must be compatible. This involves choosing a donor whose blood cells will not undergo a cross-reaction with the plasma of the recipient.

Answer 126

granulocytes agranulocytes

Answer 127

Chemotaxis

Answer 128

Diapedesis

Answer 129

Neutrophils make up 50 to 70% of circulating white blood cells (WBCs). They are characterised by their pale granules, which contain lysosomal enzymes and bactericidal compounds. With a lobed nucleus, neutrophils are the first responders to injury sites, acting as active phagocytes that engulf bacteria. They have a short lifespan of around 10 hours and can consume one to two dozen bacteria before dying, releasing chemicals that attract additional neutrophils.

Answer 130

Eosinophils account for 2 to 4% of circulating WBCs and are similar in size to neutrophils but possess red-staining granules and a bilobed nucleus. They target objects coated with antibodies and are particularly active during allergic reactions and parasitic infections. Eosinophils release enzymes that help reduce inflammation.

Answer 131

Basophils are the least common WBCs, comprising less than 1% of the population. They have deep purple granules that contain histamine and heparin, which promote inflammation by dilating blood vessels and preventing clotting. Basophils migrate to injury sites and release their granules into interstitial fluids, enhancing local inflammation and attracting eosinophils and other basophils.

Answer 132

- Monocyte Proportion: Make up 2–8% of WBCs and are the largest type, about 2-3 times the size of RBCs. - Circulation and Differentiation: Circulate briefly before becoming free macrophages in tissues, where they act as mobile phagocytes. - Functions at Injury Sites: Arrive after neutrophils, release chemicals to attract other immune cells, and stimulate fibroblasts to produce scar tissue.

Answer 133

- Proportion and Size: Lymphocytes make up 20–30% of WBCs and are slightly larger than RBCs, with a large nucleus surrounded by a thin cytoplasmic halo. - Role in Immunity: Primary cells of the lymphatic system, essential for specific immunity against pathogens. - Types and Functions: * T Cells: Directly attack foreign cells. * B Cells: Differentiate into plasma cells that produce antibodies. * Natural Killer (NK) Cells: Conduct immune surveillance and destroy abnormal cells, like cancer cells.

Answer 134

The heart, about the size of a fist, consists of four muscular chambers: the right and left atria and the right and left ventricles. These chambers work together to pump blood through two circuits: the pulmonary circuit, which transports carbon dioxide-rich blood from the heart to the lungs for gas exchange and returns oxygen-rich blood to the heart; and the systemic circuit, which carries oxygen-rich blood to the body's cells and returns carbon dioxide-rich blood back to the heart.

Answer 135

- Right Side of Heart: The right atrium collects deoxygenated blood from the systemic circuit, while the right ventricle pumps it to the lungs via the pulmonary circuit for oxygenation. - Left Side of Heart: The left atrium receives oxygenated blood from the lungs, and the left ventricle pumps it through the systemic circuit to supply the body. - Circulatory Flow: Blood flows in sequence through these circuits, moving from systemic to pulmonary and back, ensuring oxygenation before returning to body tissues. Blood Vessel Roles: - Arteries: Transport blood away from the heart (oxygenated in systemic, deoxygenated in pulmonary). - Veins: Return blood to the heart (deoxygenated in systemic, oxygenated in pulmonary). - Capillaries: Facilitate gas, nutrient, and waste exchange with tissues, linking arteries and veins in both circuits.

Answer 136

The pericardium surrounds the heart and consists of two parts: the outer fibrous pericardium and the inner serous pericardium. The fibrous pericardium is made up of a dense network of collagen fibers that stabilise the position of the heart and associated vessels within the mediastinum.

Answer 137

serous pericardium parietal visceral 50

Answer 138

The visceral layer of the serous pericardium (epicardium) covers the surface of the heart and consists of two layers: a mesothelium and an underlying layer of areolar tissue. The parietal layer of the serous pericardium is made up of an outer dense fibrous layer and an inner mesothelium.

Answer 139

The myocardium is the cardiac muscle tissue forming the atria and ventricles. It includes cardiac muscle cells, connective tissues, blood vessels, and nerves. The atrial myocardium is thin and organized into layers that form figure eights as they connect both atria. In contrast, the ventricular myocardium is thicker, with muscle orientation varying from layer to layer; the most superficial muscles wrap around both ventricles, while deeper layers spiral around and between them.

Answer 140

The endocardium covers the inner surfaces of the heart, including the heart valves, and consists of simple squamous epithelium that is continuous with the endothelium of the attached great vessels.

Answer 141

- Intercalated discs form junctions between adjacent cardiac muscle cells. - Cardiac muscle cells rely on aerobic respiration for energy, containing many mitochondria and large stores of myoglobin, glycogen, and lipids. - Their T tubules are shorter than those in skeletal muscle and do not form triads with the sarcoplasmic reticulum. - Cardiac muscle has a greater number of blood vessels than red skeletal muscle tissue. - Cardiac muscle cells can contract without nervous system stimulation.

Answer 142

myocardium functional syncytium

Answer 143

Desmosomes Fascia adherens Gap junctions

Answer 144

- Structure and Function: The cardiac skeleton is a connective tissue framework that supports the heart, distributes muscle contractions, isolates atrial and ventricular cells, and adds elasticity. - Connective Tissue Composition: Made of reticular, collagen, and elastic fibres; each cardiac muscle cell has an elastic sheath, and cells are connected by fibrous cross-links. - Connective Tissue Layers: These layers form dense bands that encircle the bases of major vessels (pulmonary trunk, aorta), surround the heart valves, connect fibrous rings around valve openings, and separate atria from ventricles.

Answer 145

1. Stabilises the positions of muscle cells and valves. 2. Provides support for cardiac muscle cells, blood vessels, and nerves within the myocardium. 3. Distributes forces of contraction. 4. Reinforces valves, preventing overexpansion. 5. Offers elasticity, returning the heart to its original shape after contraction. 6. Physically isolates atrial muscle cells from ventricular muscle cells, which is vital for coordinating cardiac contractions.

Answer 146

The right coronary artery (RCA) circles the heart to the right (when viewed from above) within the coronary sulcus. In addition to the atrial branches, it gives off two major branches: the right marginal branch and the right posterior interventricular branch. The right coronary artery branches off the ascending aorta and turns to the right, lying within the coronary sulcus between the right auricle and the pulmonary trunk. In approximately 60% of individuals, the RCA is the dominant coronary artery, providing the posterior interventricular branch.

Answer 147

1. The right atrium. 2. A portion of the left atrium. 3. The interatrial septum. 4. The entire right ventricle. 5. A variable portion of the left ventricle. 6. The postero-inferior one-third of the interventricular septum. 7. Portions of the conducting system, including the sinoatrial (SA) node.

Answer 148

atrial branches

Answer 149

marginal branch posterior interventricular branch

Answer 150

sinoatrial (SA) atrioventricular (AV)

Answer 151

Honestly just look

Answer 152

outer adventitia

Answer 153

vasa vasorum

Answer 154

Arteries: - Walls: Thick with abundant smooth muscle and elastic fibres to handle high pressure. - Lumen: Smaller, circular, and retains shape in sections; walls contract, constricting the lumen. - Lining: Non-contractile endothelial lining that folds when constricted, creating a pleated appearance. - Valves: None, as blood flow is maintained by high heart-generated pressure. Veins: - Walls: Thinner, with less smooth muscle and elastic content due to lower pressure. - Lumen: Larger and often collapses in sections, appearing flattened or distorted. - Lining: Smooth, unfolded lining without pleats. - Valves: Present to prevent backflow, especially in low-pressure areas such as the limbs.

Answer 155

ventricular systole diastole

Answer 156

Elastic arteries are large vessels (up to 2.5 cm in diameter) that carry significant blood volumes from the heart. Examples include the aorta, pulmonary artery, and main branches like the carotid and subclavian arteries. The intima is thick, with an endothelial layer and elastic connective tissue separated from the media by the internal elastic membrane. The media has many elastic fibers and few smooth muscle cells, making the walls highly resilient to pressure changes without contracting in response to stimuli.

Answer 157

Muscular arteries are medium-sized vessels (around 4 mm in diameter) that deliver blood to skeletal muscles and organs. Most visible arteries are muscular, though many are too small to see without magnification. The media of muscular arteries is thicker and contains more smooth muscle cells than elastic arteries, with an internal elastic membrane separating it from the intima. The autonomic nervous system and local signals control their lumen diameter by adjusting the muscle in the media, allowing for independent regulation of blood flow to specific organs.

Answer 158

Arterioles

Answer 159

Capillaries

Answer 160

Continuous Fenestrated

Answer 161

1. Diffusion across Endothelial Cells: Lipid-soluble materials, gases, and water move through the cell membranes via simple diffusion. 2. Diffusion through Gaps: Water and small solutes pass through the gaps between adjacent endothelial cells, while larger solutes can diffuse through gaps in sinusoids. 3. Diffusion through Pores: In fenestrated capillaries and sinusoids, water and solutes can move through specialized pores. 4. Vesicular Transport: Endothelial cells use vesicular transport, involving endocytosis on the luminal side and exocytosis on the basal side, to transport water and specific solutes, both bound and unbound.

Answer 162

capillary bed autoregulation

Answer 163

collaterals anastomosis

Answer 164

Arteriovenous (AV) anastomoses

Answer 165

Venules postcapillary venules

Answer 166

capacitance vessels

Answer 167

Anastomoses

Answer 168

aortic valve ascending aorta aortic arch brachiocephalic left common carotid left subclavian

Answer 169

- Bronchial arteries supply the lungs. - Pericardial arteries supply the pericardium. - Mediastinal arteries supply the structures in the mediastinum. - Esophageal arteries supply the esophagus

Answer 170

- Intercostal arteries supply the chest muscles and the vertebral column. - Superior phrenic arteries provide blood to the upper surface of the diaphragm.

Answer 171

1. Lumbar veins: Drain the lumbar region and connect to the azygos vein (right side) and hemi-azygos vein (left side), which both empty into the superior vena cava. 2. Gonadal veins: Drain the ovaries or testes; the right gonadal vein drains directly into the inferior vena cava, while the left drains into the left renal vein. 3. Hepatic veins: Drain blood from the liver into the inferior vena cava at the level of vertebra T8-T10. 4. Renal veins: Collect blood from the kidneys, and are the largest vessels draining into the inferior vena cava. 5. Adrenal veins: Drain the adrenal glands; the right typically drains into the inferior vena cava, while the left drains into the left renal vein. 6. Phrenic veins: Drain the diaphragm; similar to the adrenal veins, only the right phrenic vein drains into the inferior vena cava, while the left drains into the left renal vein.

Answer 172

The hepatic portal system is a specialised venous system that begins in the capillaries of the digestive organs and ends in the liver sinusoids. Unlike other organs, the liver drains directly into the inferior vena cava. Instead of blood from the digestive organs traveling straight to the inferior vena cava, it first flows into the hepatic portal vein, which is formed by the union of veins from the celiac, superior mesenteric, and inferior mesenteric arteries. This portal system is significant because it transports nutrient-rich blood, containing absorbed substances from the stomach and intestines, directly to the liver for processing, storage, or excretion. Blood in the hepatic portal vein often has elevated levels of glucose and amino acids compared to other systemic veins.

Answer 173

- Systemic capillaries, with a pressure of about 35 mm Hg, push water and solutes into interstitial fluid, moving around 3.6 L daily. This fluid is then returned to the bloodstream by lymphatic vessels, maintaining blood volume and balancing interstitial fluid composition. Any damage to a major lymphatic vessel can disrupt this balance, risking a rapid loss of blood volume.

Answer 174

Micturition = the act of urinating

Human Anatomy Flashcards

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