EXAM 4 Objevtives

describe the changes in sarcomere structure & appearance as muscle contraction occurs

when a sarcomere contracts, the Z line move closer together & the I band gets smaller

explain the sliding filament mechanism of muscle contraction

a muscle fiber contracts when myosin filaments pull actin filaments closer together & shorten sarcomeres within a fiber

explain why the H zone & I band get smaller when the skeletal muscle contracts, & why does the A band stay the same?

the H zone & I band decrease in size bc of actin & myosin overlap. A band remains unchanged since myosin length stays constant

explain the molecular events underlying the sliding filament model of muscle contraction

cross-bridge formation, power stroke, detachment, & re-cocking repeat using ATP

describe how ATP is involved in muscle contraction

provides energy for myosin head detachment & re-cocking, power Ca²⁺ pumps to reset the sarcoplasmic reticulum

explain how tropomyosin & troponin help regulate muscle contraction

tropomyosin blocks actin binding sites; troponin, upon Ca²⁺ binding, moves tropomyosin, enabling myosin to bind

beginning with an action potential in a motor neuron, describe the sequence of events at the molecular level that leads to skeletal muscle contraction

with an action potential in a motor neuron, skeletal muscle contraction occurs through the release of acetylcholine, triggering an action potential in the muscle, which leads to calcium release from the sarcoplasmic reticulum, enabling myosin to bind to actin and generate contraction via the sliding filament mechanism

explain the events that occurs when an action potential arrives at a muscle fibers’ motor endplate, causing the muscle to be depolarized

action potential triggers release, binds to receptors, causing muscle depolarization

explain the role of sarcoplasmic reticulum in muscle contraction

stores & releases Ca²⁺, critical for muscle contraction

describe the composition of vertebrate bone

compact & spongy bone; contains osteocytes & collagen; composed of cartilage, ligaments, & bone

explain the functions of osteoblasts

build bone (bone matrix production)

explain the functions of osteoclasts

reabsorb bone tissue (breakdown & remodeling)

explain how a bone fracture is repaired

1. blood from ruptured blood vessels forms a clot surrounding the ends of the broken bone

2. a callus of cartilage replaces the clot

3. bone gradually replaces the cartilage in the callus

4. when mature bone completely replaces the callus & the original shape of the bone has been mostly restored, the fracture is healed

explain how bone remodels in response to mechanical stresses

loaded mechanical stress is converted to a series of biochemical reactions, and finally activates osteoclasts and osteoblasts to cause bone resorption and formation

explain why some cells respond to chemical hormones and others do not.

cells only respond to chemical hormones if they possess specific receptor proteins on their surface or inside the cell that perfectly match the shape of the hormone molecule, acting like a "lock and key" mechanism

describe the pathway by which endocrine hormones move from secreting cells to target cells

endocrine hormones travel via blood to target cells with specific receptors

name the 3 classes of endocrine hormones

steroid, peptide, & amino acid-derived response

explain how steroid & peptide hormones differ in their mechanisms of action

steroid hormones do not affect the synthesis of proteins whereas peptide hormones affect the activity of proteins already in the cell

explain the process of negative feedback

response counteracts the initial stimulus; shuts off original stimulus or reduces its intensity

explain the process of positive feedback

increases original stimulus to push variable farther from set point; amplifies stimulus that created the response; rate constantly increases until action is complete; least common

summarize the functional relationship between the hypothalamus and the anterior pituitary gland and the posterior pituitary

hypothalamus sends signals in the form of releasing hormones to tell the anterior and posterior pituitary when to release (secrete) its hormones

summarize the site of production, regulation, and effects of the pituitary hormone

produced in the pituitary gland, located at the base of the brain, and is primarily regulated by the hypothalamus

summarize the site of production, regulation, and effects of the thyroid hormone

production is regulated by a negative feedback loop. The hypothalamus produces thyrotropin-releasing hormone, which stimulates the anterior pituitary to produce thyrotropin

summarize the site of production, regulation, and effects of the parathyroid hormone

produced by the parathyroid glands, located on the posterior surface of the thyroid gland. Its release is regulated by blood calcium levels: low calcium stimulates PTH secretion, while high calcium inhibits it

summarize the site of production, regulation, and effects of the pancreas

located in the abdomen behind the stomach, produces digestive enzymes (exocrine function) and hormones like insulin and glucagon (endocrine function) which are primarily regulated by blood sugar levels

summarize the site of production, regulation, and effects of the adrenal hormone

produce hormones like cortisol and aldosterone in the outer layer (cortex) and adrenaline (epinephrine) in the inner layer (medulla), primarily regulated by the pituitary gland through ACTH, and their main effects are to manage stress response, blood pressure, and electrolyte balance by controlling sodium and water retention in the body

summarize the site of production, regulation, and effects of the gonads hormone

include the testes in males and ovaries in females, are the primary reproductive organs responsible for producing gametes (sperm and eggs) and sex hormones like testosterone (males) and estrogen/progesterone (females)

describe the normal function of growth hormone and explain what goes wrong in cases of pituitary dwarfism, gigantism and acromegaly

• deficiency in children-dwarfism

• excess in children-giantism

• excess in adults-acromegaly

describe how the hormones of the pancreas act together to regulate the concentration of glucose in the blood

when a person's blood sugar is too high, their pancreas secretes more insulin. When their blood sugar levels drop, their pancreas releases glucagon to raise them

diabetes: (juvenile) autoimmune disorder; do not produce insulin

type 1

diabetes: (adult onset) do not use insulin properly; known as insulin resistance

type 2

describe the role of the adrenal glands in the stress response

release cortisol during times of stress to help your body get an energy boost and better handle an emergency situation (cortex & medulla)

explain how the parathyroid & thyroid glands regulate calcium levels in the body

when calcium concentrations are low, the parathyroid gland secretes PTH

when calcium concentrations are high, the thyroid gland secretes calcitonin

describe the adaptations of respiratory surfaces for diffusion

large surface area, thin membranes, moist surfaces

explain adaptation for respiratory gas exchange in terms of Fick’s law of diffusion

the amount of gas that moves across a tissue sheet is proportional to its area and inversely proportional to its thickness

explain how bulk flow & diffusion interact to promote gas exchange between air & blood and between blood & tissues

Bulk flow transports gases like oxygen and carbon dioxide within blood vessels, while diffusion enables the movement of these gases between blood and tissues or air

compare water & air as respiratory media

water lower O₂ concentration than air

define partial pressure and how it’s calculated

the individual pressure exerted by each gas within a mixture of gases

explain the 4 stages of gas exchange in animals with circulatory system & lungs

ventilation, diffusion of oxygen into the blood, perfusion (transport of blood to tissues), diffusion of oxygen from blood into tissues for use by mitochondira

explain the process of ventilation in mammalian lungs

during inhalation, air enters the body through the nasal cavity located inside the nose

describe how O₂ & CO₂ are transported & exchanged between lungs & body cells

Oxygen (O2) is transported from the lungs to the body cells by binding to hemoglobin in red blood cells, while carbon dioxide (CO2) produced by cells is transported back to the lungs in the blood, where it is exchanged for oxygen at the alveolar level, primarily through the process of diffusion across a thin membrane separating the air in the alveoli from the blood capillaries

describe the nature of an oxygen dissociation curve

a graph with oxygen partial pressure along the horizontal axis and oxygen saturation on the vertical axis, which shows an S-shaped relationship

explain the mechanism & benefits of the Bohr effect

allows for better oxygen unloading in metabolically active peripheral tissues like skeletal muscle during exercise.

summarize the mechanisms by which oxygen & carbon dioxide are transported in the blood

oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lung

explain how the brain controls the breathing rate

the medulla oblongata sends signals to the heart and diaphragm in reaction to carbon dioxide and oxygen levels, allowing for easier breathing

explain the relationship between P_CO2 & pH in the regulation of breathing

The amount of carbon dioxide exhaled, and consequently the pH of the blood, increases as breathing becomes faster and deeper

explain the role of carbonic anhydrase (CA) in eliminating CO₂ from the body

facilitates the conversion between carbon dioxide (CO₂) and water (H₂O) to form carbonic acid (H₂CO3) and its dissociative ions (HCO₃− and H⁺)

explain the key features shared by all circulatory systems

delivers nutrients and oxygen to all cells in the body

• Heart pumps hemolymph through vessels into hemocoel

• Extracellular fluid is the same as the fluid in the circulatory
  system and is called hemolymph

• Hemolymph leaves the vessels to filter through the tissues
  before returning to the heart

• Blood directly bathes the internal organs

• Animals expend less energy on circulating blood
  (metabolically expensive)

• Less efficient at supply O2 & nutrients to tissues

open circulatory system

• Blood pressure & flow rates are higher

• Circulating fluid (blood) completely contained in a
  continuous system of vessels.

• Control flow blood to selective tissues & organs to match
  needs

• Animals tend to be larger & more active

closed circulatory system

describe the 3 types of vertebrate hearts

• 2-chambers: one atrium & one ventricle (fish)

• 3-chambers: two atria & one ventricle (amphibian/reptile)

• 4-chambers: two atria & two ventricles (bird/mammal)

describe the differences between single & double circulatory systems

in a single circulation, blood flows to and from the heart through a single pathway, whereas in double circulation there are two separate pathways that are connected to the heart through which oxygenated and deoxygenated blood flows

trace the flow of blood through a four-chambered heart, naming the structures through which the blood passes and explaining the function of each.

right atrium → right ventricle → lungs → left atrium → left ventricle → body

explain the structure of cardiac muscle & how it helps produce coordinated contraction in each heart chamber

composed of branched, interconnected cells called cardiomyocytes, which are joined together at specialized junctions called intercalated discs, containing gap junctions and desmosomes

explain the cardiac cycle & how electrical impulses are conducted through the human heart

The electrical stimulus travels down through the conduction pathways and causes the heart's ventricles to contract and pump out blood

explain the meaning of the tracings on an electrocardiogram

translates the hearts electrical activity

structure & function of arteries

carry oxygen-rich blood from your heart to your body. they handle a large amount of force and pressure from your blood flow but don't carry a large volume of blood

structure & function of arterioles

small blood vessels that carry blood away from your heart, are connectors between your arteries and capillaries. They control your blood pressure and blood flow throughout your body, using their muscles to change their diameter. They also link to capillaries to exchange oxygen, nutrients and waste.

structure & function of capillaries

the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins). The primary function is the exchange of materials between the blood and tissue cells

structure & function of venules

very small blood vessels that connect your capillaries with your veins throughout your body. have the important function of moving blood that contains waste and lacks oxygen from your capillaries to your veins

structure & function of veins

Thin, less elastic walls help them handle high volumes and low pressure. don't have to carry highly pressurized blood, but they do have to carry large volumes of deoxygenated blood back to your heart

explain the forces that cause water to leave & reenter the capillaries

osmotic pressure (due to hydrostatic pressure which pushes fluid out of the capillary at the arterial end, while it reenters the capillary at the venous end mainly due to osmotic pressure created by the concentration gradient of proteins in the blood, drawing fluid back in)

describe each component of blood & its function

• plasma: main component of blood & consists mostly of water, with proteins, ions, nutrients, & wastes mixed in.

• formed elements:

list the 3 cell-based components of blood & describe the principal functions

• red blood cells: responsible for carrying oxygen & carbon dioxide

• white blood cells: part of the immune system & function in immune response

• platelets: responsible for blood clotting

explain the sequence of events during blood clotting

1. damaged cells expose collagen, which activates platelets, causing them to stick and form a plug

2. both damaged cells and activated platelets release chemicals that convert prothrombin into the enzyme thrombin

3. thrombin catalyzes the conversion of fibrinogen into protein fibers called fibrin, which forms a meshwork around the platelets and traps red blood cells

explain how the lymphatic system returns interstitial fluid to the blood & why it’s important

As the interstitial fluid begins to accumulate, it is picked up and removed by tiny lymphatic vessels and returned to the blood. As soon as the interstitial fluid enters the lymph capillaries, it is called lymph. Returning the fluid to the blood prevents edema and helps to maintain normal blood volume and pressure

list the 5 processes that occur in a digestive tract

ingestion, mechanical digestion, chemical digestion, absorption, elimination

describe the structural adaptations that increase the surface area of the digestive tract

villi & microvilli

explain the digestive process that occur in the mouth

the digestive process starts in your mouth when you chew:

the tongue mixes food with saliva; moistens and lubricates the food; contains salivary amylase, which initiates breakdown of starch; salivation is controlled by the nervous system

explain the digestive processes that occur in the stomach

food converted to thick, acidic liquid called chyme; peristalsis moves food downward and into small intestine; food leaving the stomach passes through pyloric sphincter, band of muscle at the base of the stomach; pyloric sphincter opens and closes to regulate the rate at which the stomach empties

explain the digestive processes that occur in the small intestine

receives

• acidic chyme from stomach

• digestive enzymes (peptidases, nucleases, maltase, lactase, sucrase) from cell lining small intestine

• digestive enzymes (amylase, lipase, proteases, nucleases) and alkaline bicarbonate from pancreas

• bile from liver and gallbladder; emulsifies fats into droplets making them easier to digest

describe the importance of villi & microvilli in digestion

villi move nutrients from lumen (opening) of the intestine into the circulatory system

microvilli increase the surface area so each villus can absorb maximum amounts of nutrients

describe the role of the liver in the digestive process

make and secrete bile & to process & purify blood containing newly absorbed nutrients that are coming from the small intestine

describe the role of the pancreas in the digestive process

secretion of pancreatic fluid the duodenum, which includes

• bicarbonate

• trypsin & chymotrypsin

• pancreatic amylase

• lipase

explain the digestive processes that occur in the large intestine

absorb water, minerals, and some of the remaining nutrients from food. helps form firm feces, which are stored in the rectum until elimination from the anus

compare lipid absorption with absorption of other nutrients

lipid can diffuse through plasma membrane

discuss how the digestive process is regulated

regulated by a complex interplay of neural & hormonal signals that coordinate the activity of various organs to ensure the efficient breakdown & absorption of nutrients